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Operation Downfall 4: Allied plans for Olympic and Coronet

Operation Downfall 4: Allied plans for Olympic and Coronet

Operation Downfall 4: Allied plans for Olympic and Coronet

The Allied Plans (1): Olympic
The Allied Plans (2): Coronet

The Allied Plans (1): Olympic

While the overall plan for the invasion of the Japanese Home Islands was codenamed Operation Downfall, it was made up of two component operations, Olympic and Coronet. Many of the operations in the Pacific War were undertaken in order to not only eliminate centres of Japanese resistance but to provide bases for up-and-coming operations. So it was with Olympic and Coronet. The Operations in the Philippines and Central Pacific (particularly against the Mariana Islands) were designed to provide forward bases for use by Allied forces invading Okinawa (Operation Iceberg) and Iwo Jima (Operation Detachment). Okinawa in turn was to provide the forward staging base for Olympic, the invasion of Kyushu, the southernmost of the Japanese Home Islands, which in its turn, would provide the staging base for Coronet, the invasion of the Tokyo Plain on Honshu and the final blow aimed at forcing the Japanese to surrender.

The fundamental concept behind Olympic therefore was to seize Kyushu (or at least the southern portion of it) for its airfields and bays in order to provide staging areas for the forces to undertake and support Coronet. As bases were secured, these air and naval forces would deploy forward to attack northern Kyushu, Shikoku and Honshu and to breach the Straits of Tsushima. Land-based airpower on Kyushu could bring the whole of Japan under attack while the navy could complete the blockade of the Home Islands. Olympic called for nine divisions formed into three corps to land simultaneously on three separate beaches, then drive inland to capture airfields and encircle Kagoshima Bay. A fourth corps of two divisions would form a floating reserve. The ground forces for Olympic would come from forces already deployed in the Pacific. I Corps would land at Miyazaki, XI Corps would land at Ariake Bay on the eastern side of the Osumi Peninsula. The three Marine divisions of the V Amphibious Corps would land on the western side of the Satsuma Peninsula near Kushikino. The floating reserve, IX Corps, would land at the southern end of the Satsuma Peninsula on X-Day plus 4 if it had not been committed elsewhere. After securing their lodgements, the invasion forces would move to accomplish three additional tasks – capture the interior plains of both peninsulas where the Japanese airfields were located, capture the port of Kagoshima as well as securing the shores and entrance to the bay, and drive northward to the southern edge of the central range of mountains to seal off southern Kyushu from the remaining Japanese forces in the north of the island. Allied forces would then secure a line running diagonally across the island from Tsuno in the east to Sendai in the west, thus securing the southern third of Kyushu (AFPAC Staff Study, ‘Olympic Operation in Southern Kyushu’, 28 May 1945, RG 165, NARA).

As mentioned previously, the main problem in the Pacific was shipping. The vast distances encountered in the theatre, the competing demands of other theatres (especially Europe) and enormous construction requirements all combined to produce a near permanent shipping shortage. Redeployment, the 'roll-up' and movement of rear areas and preparations for Olympic all added to the strain in the spring of 1945. The command staffs agreed that each command would be responsible for the procurement and operation of shipping under its control. The control of shipping and port facilities was a more pressing problem than the scarcity of shipping. Shipping requirements were carefully balanced – the control of tangled shipping networks and congested port facilities could create chaos and so elaborate procedures were worked out between AFPAC and POA to call forward shipping as needed and settling competing claims on port facilities. The three marine divisions would be transported and landed by Nimitz's command. Once ashore, items common to both the marines and the army would be supplied by AFPAC, items peculiar to the Marine Corps and Navy would be supplied by Nimitz, who would also support the marines' construction requirements.

The agreement on future planning simply extended the established practice of inter-command conferences. The detailed planning for the operation itself fell to Krueger's Sixth Army staff and Turner's Amphibious Forces Pacific staff. Turner's PHIBISPAC force would carry the assault forces from Sixth Army to their landing beaches and have command until Krueger's headquarters was established on Kyushu. Turner therefore sailed to the Philippines and on 14 June 1945 anchored his command ship USS Eldorado in Manila Bay right next to where the Sixth Army headquarters was encamped. On the same day that happened, a number of Marine officers, specialists in quartermaster, engineering, medical, intelligence, ordnance, transportation and signal arrived in Manila Bay to establish a liaison for V Amphibious Corps. There, along with the headquarters of Fifth Fleet (the command responsible for the landing force and gunfire support), they hammered out the detailed plans in a series of conferences – while each staff worked in its own headquarters, they resolved their differences and coordinated plans in a series of detailed planning conferences, working until the last week of the war. Towards the end, the conferences became almost continuous but eventually four detailed coordinated plans, each for Sixth Army, Far East Air Forces, Fifth Fleet and Amphibious Forces Pacific, emerged, along with detailed annexes regarding specialised subjects such as deception, communications and logistics. Once MacArthur and Nimitz had decided not to form a permanent inter-theatre planning group, the problem was then how they would correlate the different plans. Indeed, several months earlier, Marshall had raised this same question with MacArthur and suggested that he may want to relocate his headquarters with Nimitz for the invasion of Japan. MacArthur's reply was in the negative. On 6 June, Marshall relayed the suggestion from Admiral King that MacArthur move his headquarters to Guam so as to be in personal contact with Nimitz for the preparations for Olympic. MacArthur sent back "Please tell Admiral King that I disagree totally with his concept and that a long campaign experience has convinced me that if there is any one feature of a field commander that must be left to his sole judgement it is the location of his command post and the actual disposition of his own person." Finally, Nimitz tried to prevail on MacArthur to establish his advanced headquarters on Guam well in advance of the operation and promised he could furnish staff space and quarters for MacArthur comparable to his own. The reply remained the same.

The AFPAC Staff Study and CINCPAC study (AFPAC Staff Study, ‘Olympic Operation in Southern Kyushu’, 28 May 1945, RG 165, NARA; CINCPAC Staff Study ‘OLYMPIC’, 18 June 1945, RG 218, NARA) were completed by mid-June. These two preliminary planning documents contained the essential information that the lower echelon headquarters would need in order to draft the more detailed operation plans. The studies defined what the mission was, gave the concept of operation, outlined the command relationships and the rules for coordination and finally, listed the forces that would be employed. The forces to be organised and used in Olympic were mirrored in both staff studies. To carry out the naval and amphibious phases of the operation, Nimitz designated two fleets – the Third (under Admiral William Halsey) and Fifth (under Admiral Raymond Spruance). The Third Fleet that contained a large contingent of attack carriers that would provide almost two thousand aircraft to attack Japanese communications and transportation networks before the invasion and to cover the landings. The Fifth Fleet would carry the troops to the landing zones and provide gunfire support for the landings. Under Spruance came Admiral Turner (Commander Amphibious Forces Pacific) who would command the amphibious operations, with the Third, Fifth and Seventh Amphibious Forces, tasked with landing the assault forces at Ariake Bay, Kushikino and Miyazaki. MacArthur's counterparts two Halsey's and Spruance's fleets were the Sixth Army under General Walter Krueger and the Far East Air Forces under General Kenney. The Sixth Army would conduct the land campaign on Kyushu and the Far East Air Forces would support the invasion from bases on Okinawa and begin moving units forward onto bases on Kyushu from around X-Day + 2. The Sixth Army would also command the assault forces which were formed into four corps. Each corps was matched up with one of Turner's amphibious forces. I Corps, under Major General Innis P Swift would be transported to Miyazaki and put ashore by Seventh Amphibious Force. Lt General P Hall's XI Corps would be landed by Third Amphibious Force at Ariake Bay, while Major General Harry Schmidt's V Amphibious Corps of three marine divisions would be put ashore by the Fifth Amphibious Force on the Satsuma Peninsula. Major General Charles P Ryder commanded the IX Corps would be carried by the Reserve Amphibious Force and either reinforce one of the principle landing operations or if not needed, landed at the tip of the Satsuma Peninsula on or around X-Day + 4. As these plans were completed so the individual corps and amphibious forces began to draft their own plans, which were published in the last days of the war, with corps staffs starting to draft Olympic orientation briefings for their respective division staffs.

The preliminary phase of Operation Olympic would start five days before the main landings (X-Day – 5) and see the 40th Infantry Division as well as the 158th Regimental Combat Team (RCT) landing on a number of offshore islands in order to secure them for the construction of radar outposts, emergency anchorages and seaplane bases. On X-Day, unless the landings had to be staggered due to bad weather or other unforeseen events, the three corps (I, XI and V Amphibious) would simultaneously assault their respective beaches, as outlined above. IX Corps would act as the floating reserve, if necessary reinforcing one of the landings with the 98th Infantry Division, and if ordered to do so, land (with or without the 98th) on the south coast of the Satsuma Peninsula, east of Makurazaki anytime after X-Day + 3. Each corps would establish a beachhead and begin the reconstruction of roads and airfields. They would each then move inland securing more airfields as well as opening Kagoshima Wan for use by the US Navy, finally looking to eliminate enemy forces in southern Kyushu as they advanced northwards establishing a defensive line running across the island from Sendai on the west coast to Tsuno on the east coast. The operation was to be completed in ninety days and involve the 582,560 soldiers (of which 323,410 were combat troops) of Krueger's Sixth Army. (Sixth Army Field Order No. 74, Troop List, 28 July 1945, Records of the Strategic Plans Division, Box 187, NHC) The assault elements would land at beaches having codenames based on the United States premier obsession – motor cars. The potential landing areas in southern Kyushu were designated 'beach zones', having names that included Taxicab, Roadster, Limousine, Station Wagon, Town Car, Delivery Wagon and Convertible. In turn, each 'beach zone' was subdivided into possible landing beaches, with codenames that related to name of the 'beach zone'. Thus Taxicab had Zephyr, Winton, Stutz and Studebaker beaches. Limousine included Plymouth, Packard and Overland beaches; Station Wagon included Franklin, Ford, Essex, Dusenburg and De Soto beaches; while the Town Car zone included Cord, Chrysler and Chevrolet beaches. In the same way, the landing beaches designated for the 40th Infantry Division on Koshiki Retto were named after automobile parts – Brakedrum, Windshield, Cylinder, Gearshift, Hubcap, Rumbleseat, Sparkplug etc. Subdivisions of each beach were designated by colours and numbers, for example, Austin Yellow 1 and Austin Yellow 2. (Amphibious Forces Pacific Fleet Operations Plan No. A11 – 45, 10 August 1945, NHC)

At first glance, all the beaches that were on the map of southern Kyushu appeared inviting, with them being long and open, were relatively flat and were between fifteen and thirty kilometres long. It was the terrain behind the beaches that was of greater concern to the attackers. The landing beaches at Miyazaki, Ariake Wan, Kaimon Dake and Kushikino were all backed by rugged hills that were easily defendable and varied between fifty and two hundred metres in height. They stood between one and five kilometres behind the beaches and most ran the entire length of the beach. Corridors led away from the beach into the interior but themselves posed problems for any advance as anyone looking at small-scale maps might think that they led into the interior plains from the southern ends from both the Miyazaki and Ariake Wan beaches without any problems but were in fact dominated by heights that stood between ten and fifteen kilometres inland, while another range of rugged, broken hills lay immediately behind the beaches on Western Kyushu, particularly those near Kaimon Dake and Kushikino. Assaulting the beaches at Miyazaki was I Corps. From the beach, one can see the mountains that ring the triangular coastal plain, rising to a height of about 1200m and then heading inland, after two or three kilometres, one comes across a steep 50m bluff rising out of the plain that blocks progress down the corridor. It is here the Japanese placed a series of strongpoints sited to dominate the exits from the beaches. The corridor that exits the southern beaches towards Tano on the western side of the Honjo River was to be used as an entrance by US forces onto the Miyakonojo – Kanoya Plain. Near Tano however, there is an unbroken hill mass, rising 3 – 400m high and effectively blocking the corridor. Partitioning I Corps' landing area was the Oyodo River flowing down from the mountains with the Miyazaki airfield immediately south of the river's mouth, itself a prime objective. This layout would keep I Corps divided until it drove into Miyazaki to take the bridge across the river. The beaches in this area are long, gently sloping affairs with hard sand – ideal for amphibious operations. On 4 August 1945, I Corps published a tentative field order (I Corps Field Order, 4 August 1945, RG 94, Box 3089, File 201-3.9, WNRC) outlining the assault on Miyazaki. The plan outlined the landing of the 25th Infantry Division on Cord Beach south of the river's mouth and the 33rd Infantry Division north of it. The corps reserve would be the 41st Infantry Division and would stay afloat awaiting the order to act in one of three ways: to reinforce either of the other divisions; to follow-up the 25th on X-Day + 2; or to make an assault landing on Chevrolet Beach, immediately north of Chrysler Beach, to extend the corps beachhead. Both the 25th and 33rd would land with two regimental landing teams abreast with the 25th capturing Miyazaki airfield and then advancing south to clear any position with which the Japanese could directly fire onto Cord Beach and block any enemy advance from the south. Upon completing that task, the 25th would advance westwards down the corridor that runs towards Tano and through the mountains towards Miyakonojo where it would (hopefully) meets elements of XI Corps advancing north from its beachhead at Ariake Wan. The 33rd Infantry Division meanwhile was to capture Miyazaki itself, seize the main coastal highway and the bridge there and establish contact with the 25th Infantry Division to the south. It would then advance westwards to expand the corps beachhead and then north to take Hirose to block any enemy advance from that direction. I Corps planners noted a number of critical objectives that needed to be seized early in the campaign. These included the Miyazaki airfield, the coastal highway and the bridge across the Oyodo River (without which the corps would have no north-south communications) as well as several pieces of terrain including the ridgeline that lay two to three kilometres behind the beaches, a 100m high hill north of Miyazaki that provided observation over the whole area including Miyazake and Chrysler Beach and another hill just south of Cord Beach that could be used to enfilade the entire 25th assault area. I Corps would land, advance inland and secure the area from Sadohara in the north, through Honjo and Takaoka to Aoi Dake in the south. Even as the combat divisions would drive inland, hot on their heels would come the combat engineers and support troops of Army Service Command, Olympic, Base 3, to begin repairing and building airfields, storage facilities, bases and roads.

Ariake Wan (now Shibushi Wan) lies only 32 miles (51km) southwest of Miyazaki as the crow flies but in-between lies rough forested hills and mountains, up to 1,000m high with only a single road winding itself down the east coast. Even though Sixth Army had not designated XI Corps' assault as the main attack, the landings at Ariake Wan were still of importance to the overall success of the operation. Ariake Wan is a peninsula flanked to the east and west by 3 – 400m heights. The beach there stretches some fifteen kilometres along the coast and the small port of Shibushi at the eastern end makes it even more inviting for amphibious operations. A rapid advance inland from here would place the invaders on the Miyakonojo-Kanoya Plain, an area of great importance as it holds a great number of airbases and has access to the head of Kagoshima Bay. The area however holds some good defensive sites. Heavy guns could have been placed on both flanks with these heights providing excellent observation of the bay and the beaches. In addition, the small island of Biro Shima which lies five miles offshore and right in the middle of the bay would have provided a useful gun platform, allowing the defenders to fire at the invasion fleet and any of the beaches. The eastern half of the beach has a continuous ridge running behind it at a height of between 25 – 50 metres high at a distance of between 500 and 1000 metres. This ridge is cut in a number of places by streams coming down from the hills and is where the Japanese sited a number of strongpoints designed for all-round defence and linked by tunnels under the hills, manned by elements of the 86th Division. Heavy 150mm artillery pieces could fire from cave openings in the hillsides onto the beaches or stream valleys. The western half of the beach the Kushira River plain makes the terrain much flatter and more open with the main route to Kanoya running through the area. Moving into the interior however, there is another ridgeline at a distance of 15km (9 miles), averaging around 50m high upon which the Japanese positioned the 188th Infantry Regiment to block mobile forces coming off the beaches and into the interior. Conducting the assault would be Lt Gen Hall's XI Corps, composed of the veteran 1st Cavalry, Americal and 43rd Infantry Divisions plus the 112th Regimental Combat Team. On 6 July 1945, the corps Chief of Staff, Brig Gen John A. Elmore called together all his staff officers to begin planning the assault (XI Corps Staff Conferences on OLYMPIC, 6-9 July 1945, RG 94, Box 4159, File 2.11-0.5, WNRC). Logistics were of the greatest concern as not only were the divisions and all their equipment to be landed, over 35,000 tons of supplies had to be landed on and moved across the beaches in the first five days of the assault. Congestion on the beach was perhaps inevitable – the beaches could hold some sixty LSTs at any one time, about ten per mile. Elmore noted that if necessary they could be packed in 'gunwale to gunwale' but the allocation of space on the beach for supply dumps, bases, headquarters areas, casualty treatment centres etc needed detailed planning and close coordination with the Army Service Command, Olympic (ASCOM 'O') whose units would land right behind the combat units in order to start construction and repair of the bases that would accommodate the aircraft of the Far Eastern Air Forces (FEAF). Three days later, he called the commanders and staff of the 1st Cavalry Division, 43rd Infantry Division and 112th RCT to meet with XI Corps staff. The Americal Division staff, being far away in Cebu in the southern Philippines did not attend. The division received its orientation when General Elmore along with his G-2, G-3 and G-4 flew down to Luzon. While he could not offer a detailed scheme of manoeuvre as yet, while they would not have everything they wanted, they were "definitely out of the 'shoestring' department". In addition to the three divisions and single RCT, XI Corps would have four additional battalions of artillery, one battalion of antiaircraft artillery, two tank battalions, two amphibious tractor battalions, one tank destroyer battalion and two amphibious tank companies. The tank destroyer battalion would be equipped with 90mm rather than 75mm guns and six of the corps' 155mm artillery battalions would be self-propelled. All these powerful direct-fire weapons would be attached to the divisions as "caves, tunnels and other fortifications are encountered". All this additional firepower meant that XI Corps would be the heaviest going in, Elmore noting wryly "we are duly honoured". Final plans for the landing were never issued, however, some planning started to take place in early July and indicated a traditional two-up, one-back approach with the 1st Cavalry Division on the left, 43rd Infantry Division on the right, landing abreast at the head of the Ariake Wan. The role of the 112th RCT remained speculative when the war ended but it could have been placed in corps reserve to be used on one of the flanks or attached to one of the assault divisions. The Americal Division was to be the floating reserve and scheduled to cross the beaches anytime after X-Day + 2. The 43rd Division, landing on both Dusenburg and De Soto beaches was tasked with capturing Shibushi, along with its port and airfield. The division would then drive northwards along the corridor towards Miyakonojo and eventually link up with the 25th Infantry Division (from I Corps) driving westward from Miyazaki. 1st Cavalry Division meanwhile, landing on Ford Beach would advance westwards along a natural corridor towards Kanoya and the western shore of Kagoshima Bay. The end of the first phase would find XI Corps units on a line Aoki – Iwagawa – Takakuma – Kanoya (Sixth Army Field Order No. 74, Troop List, 28 July 1945, Records of the Strategic Plans Division, Box 187, NHC; and XI Corps Tentative Plan for AAA Employment for Operation OLYMPIC, 8 July 1945, RG 338, Box 17, Operations Reports and Related Records, 1944 – 46, WNRC). Such a foothold would achieve several objectives, such as the sheltered anchorages in Ariake Bay, the Japanese Naval airbases near Kanoya and Miyakonojo, where there was room for even more airfields. Japanese strategists were right in deducing that the landings at Ariake Wan presenting the gravest danger to southern Kyushu.

The beaches at Fukiagehama stretch in a 30km (19 miles) crescent along the western side of the Satsuma Peninsula and while very beautiful, presented the most difficult task for the Allied forces. The beach itself is hard white sand but is backed within about fifteen feet by ten-foot (3m) high dunes made of soft sand. Immediately behind the dunes is an area of scrub pine followed by an area between one and five kilometres deep that is solidly agricultural (ploughed and irrigated fields etc) and backed by high hills. These give way after about 10km (6 miles) to a range of small mountains, around 3 – 600m high, which are packed very closely together. These small mountains resemble areas of eastern Belgium, the Dalmatian coast of the former Yugoslavia or central Italy. Cutting through these mountains are three narrow corridors that lead across the peninsula towards Kagoshima, the shortest being 20km (12 miles). The northern few kilometres of Fukiagehama is cut off from the long beach by 20m cliffs. Between these cliffs and the city of Kushikino lie two more beaches, each only 2,000 yards wide. These beaches, codenamed Stutz and Winton, were the landing beaches for V Marine Amphibious Corps under Major General Harry Schmidt (Amphibious Corps Operation Plan, No. 1 – 45, 6 August 1945, USMC Geographic File, Japan, Box 52, WNRC). The Corps mission was to land in the Kushikino area, secure their beachhead that included Sendai and then block the advance of any enemy forces coming down the west coast. They would then advance inland to secure a line Kagoshima – Kawakimicho – Ichino – Sendai. The corps would land with the 3rd Marine and 2nd Marine Divisions abreast with the 3rd on Winton and the 2nd on Stutz. The divisions would land with two RCTs abreast with the 5th Marine Division acting as a floating reserve, prepared to reinforce either assault division or make a separate assault on Zephyr Beach to the north or Star Beach to the south. The 2nd Marine Division, after landing, would then drive southeast to block enemy attacks that might threaten the corps' right flank. By doing this, it would also secure the entrance to the narrow corridor that runs southeast across the peninsula towards Kagoshima, a route the division would have to take in order to capture the city. 3rd Marine Division would turn northwards towards Sendai to block enemy reinforcements coming south. The corps would then advance to secure the line Kagoshima – Sendai. Of all the landings, the Marines faced the toughest task. The beaches were backed by dues and they were then faced with having to cross the Ozato Gawa which ran parallel to the beach about 500 yards inland. Following this was rough terrain and rice paddies with hills up to 600 feet high providing observation of the entire beach. The roads running inland were incapable of taking a large amount of heavy traffic so the Marines would have had to be careful as to what they put on them and how much. As one V MAC planner put it, it would have been "an unpleasant landing at best." (Skates, p. 185)

IX Corps itself (under the command of Major General Ryder) lacked combat experience but still had to prepare for a whole host of possible contingencies. (IX Corps Field Order No. 1, Operation OLYMPIC, 12 August 1945, RG 94, Box 4105, File 209-3.9, WNRC) It was designated as Sixth Army's floating reserve and so was to conduct diversionary operations off Shikoku from X-Day-2 to X-Day. The 98th Infantry Division (another inexperienced formation) was to be prepared to reinforce any of the Sixth Army landings on or after X-Day+3, while the 77th Infantry Division (an experienced formation that had seen action on Guam, in the Philippines and on Okinawa) was to be prepared to do the same after X-Day+5.

The corps was also to prepare for contingency landings on the southwest tip of Kyushu from about X-Day+3 onwards. The designated beaches lay immediately west of the entrance to Kagoshima Bay and stretch westward from the bottom of Kaimon Dake, a near perfectly formed 3,000-foot volcanic cone. While the beach is around 10km long, only the eastern half is suitable for amphibious landings, the western half being backed by broken and rocky cliffs right down to the beach. The eastern half had hard, black sand but was backed by a low ridge, followed by a series of low hills, spread about in seemingly random positions. The small compartment-like spaces in-between were rice paddies. Open country opens out from behind the western end of the beach, heading towards the large airfield complex at Chiran, but the beach itself was unsuitable for amphibious landings. The two beaches selected for IX Corps were Packard Beach on the right and Plymouth Beach to the left. The 98th Infantry Division, unless committed elsewhere, would land on Plymouth Beach, drive north to seize Byu airfield and then continue its advance towards the airbase at Chiran. The 81st Infantry Division would land at Packard Beach, next to Kaimon Dake, drive straight across the peninsula to the shores of Kagoshima Bay and clear the area. The reconstruction of air and naval bases and facilities would begin almost immediately.

The 40th Infantry Division, enlarged by additions to its normal TO&E, numbering over 20,000 as opposed to just over 14,000, would be the first into battle during Operation Olympic. The division's mission was to seize a number of offshore islands to the south and west of Kyushu to capture radar sites, emergency anchorages and seaplane bases. On X-Day-5, elements of the division would assault Kuro Shima, Kuchinoyerabu Shima, Kusakaki Shima and Uji Gunto. On X-Day-4 the remainder of the division would land in the north and the south of Koshiki Retto, a large island group about thirty miles to the west of the V MAC beaches. In the same way, the 158th RCT was ordered to prepare to land, on or just after X-Day-5 on the north coast of Tanega Shima. This operation however would be contingent on the strength of Japanese air and naval defences in the Osumi Strait, the narrow channel between the Osumi Peninsula and Tanega Shima through which the amphibious forces supporting and carrying both I Corps and XI Corps would have to pass. The 11th Airborne Division, acting as the Sixth Army reserve, would embark in the Philippines on turnaround shipping and be available from X-Day+22. (AFPAC Operations Instructions No. 1/9, 3 August 1945, RG 338, Box 193, Sixth Army Engineer Section, Plans and Operations, 1943 – 45, WNRC) The divisions of the AFPAC Reserve, to be committed only on the express orders of General MacArthur, were designated on 03 August 1945. The 7th Infantry Division, stationed on Okinawa, would be ready by 10 November 1945 while the 6th Infantry Division (on Luzon) and 96th Infantry Division (on Mindoro) would be ready from around 20 November 1945. General Krueger's headquarters, on board the USS Eldorado, would move with XI Corps to Ariake Wan. After the corps headquarters moved ashore, Krueger would establish a temporary headquarters in the centre of the beach near Hishida. As the corps moved forward, the Sixth Army HQ would move inland to Matsuyama then to the Miyakonojo area. A permanent headquarters would eventually be established at Kokubu, near the top of Kagoshima Wan.

During the first months of the occupation of Japan, observers from both the V MAC and IX Corps went to southern Kyushu, studied the terrain as well as the Japanese defences and attempted to project the course of the battle had Operation Olympic been launched. Both sets of observers saw the rugged terrain of Kyushu as the chief Japanese defensive advantage and consequently the chief American problem. The rough terrain, along with the narrow corridors leading into the interior, substantially neutralised the massive American advantage of manoeuvre as their forces advanced inland. Yet both reports (V Marine Amphibious Corps Operations Report, Occupation of Japan, Appendix 3 to Annex C, 30 November 1945, Marine Historical Centre, Washington DC; IX Corps Report of Reconnaissance and Survey of Japanese Dispositions, Southern Kyushu (Operation OLYMPIC-MAJESTIC), 15 December 1945, RG 94, Box 4104, File 209-2.0, WNRC) concluded that Japanese preparations would still have been incomplete by the time the invasion, that Japanese transport, communications and supplies were completely inadequate and that Japanese plans for a rigid beach defence coupled with counterattacks from mobile forces further back in the interior would have been almost impossible to execute. Except for the gravelled national highways that ran down either coast, Kyushu roads were unimproved and incapable of handling heavy military traffic with many bridges being made of logs which were tied together with rope. Railways were better developed than roads, but these ran through many tunnels and defiles which would have been susceptible to air attack. Japanese military communications depended heavily on commercial telephones along with a few older radios and field telephones using unburied wire The required stocks of ammunition had not been accumulated to the necessary levels, and air attack would have disrupted internal transport and communications making the distribution of supplies very difficult and for the same reason, made the Japanese plans to move units stationed in the interior and Northern Kyushu southwards to mount counterattacks very difficult indeed. The massing of American ships in forward areas and the increasing rate of air and naval sorties would have made the invasion almost impossible to hide past about X-Day-10. The pre-X-Day operations by both the 40th Infantry Division and 158th RCT against the offshore islands would have provided near certain evidence that Southern Kyushu was the target of the invasion. The objectives of the 40th Infantry Division were guarded by a few outpost units and would have fallen easily although the 158th RCT would have faced a much sterner test on Tanega Shima which was defended by some 6,000 high-quality Japanese troops. Japanese defences relied heavily on fixed coastal guns, positioned to defend harbour entrances, ports and strategic narrows. Opening fire against the invasion fleet, while achieving initial surprise, would have allowed these defences to have been quickly destroyed either by naval gunfire or air bombardment. Indeed, many of the locations of these guns were already well-known to US planners.

The observers surmised that the landing operation would have been an easier task than actually pushing inland against the rugged terrain or along the narrow corridors leading into the interior. Given the weight of the landings by I Corps at Miyazaki and XI Corps at Ariake Wan along with air and naval support would have carried the beaches. It is likely that the Japanese would have attempted to commit forces from central Kyushu and to move the 212th Division (a coastal defence division) southwards to mount counterattacks but would have faced intense US air attack and assuming they arrived, would have probably arrived piecemeal and late. Both corps however would have faced heavy fighting as they moved inland, in the inland ridges facing I Corps or the high hills flanking Ariake Wan for XI Corps. However, XI Corps faced more open country than I Corps did around Miyazaki with a wide corridor leading from the southern end of the beaches right across the peninsula to Kanoya with another leading north towards Miyakonojo. Conversely, this same open country would have allowed the Japanese to more easily reinforce their forces around Ariake Wan. Again, these would have faced interdiction from American air forces and a rapid advance by XI Corps could have held these reserves north of Miyakonojo and would have allowed the Americans to use their superior mobility and firepower to greatest advantage. The marines of V MAC undoubtedly faced the toughest challenge of Operation Olympic. The terrain and Japanese defences would have proven formidable obstacles. Behind the beach lay a low ridge and behind that lay some open country which consisted of paddy fields and dominated by mountains and wooded hills, providing excellent sites for artillery and observation. The 3rd Marine Division had to swing left and force open the corridor to Sendai while the 2nd Marine Division had to swing southeast and move towards Kagoshima, both routes being dominated by high ground. On the other hand, each assault division would only be facing a Japanese battalion defending each beach, Japanese intelligence anticipating that the American landings would take place further south and thus deploying their larger units there. Thus as the 2nd Marine Division advanced towards Kagoshima, it would have faced pressure on its right flank from the Japanese 206th and 146th Divisions, especially it became obvious that they faced being cut off in the southern tip of the peninsula. Movement southward by the 303rd Division to prevent the advance of the 3rd Marine Division towards Sendai would have been difficult, given American air activity. The broken terrain, lack of mobility and US air interdiction would have probably made a concentrated defence against V MAC impossible and Japanese forces would have been defeated in detail, yet the Japanese could choose where to make their stands, where to place their defensive positions and where to place their forces. The terrain allowed very little manoeuvre by either side and so the marines would have to fight the Japanese were they found them. Sixth Army's advance to the Tsuno – Sendai line would have been slow, just by virtue of the terrain.

The XI Corps observers who examined their corps' objectives in the southern Satsuma Peninsula also found difficult terrain and problems with the local road network. Yet they found that after the war had ended, Japanese defensive preparations had hardly begun and none of the units that were supposed to be manning the defences were in place, with none scheduled to arrive before 1 October 1945. Among the units that were scheduled to deploy there, there were endemic equipment shortages and haphazard training. The units had made no plans to construct obstacles or lay minefields or conduct a defence in-depth. The 146th Division, the central coastal defence unit in the IX Corps area had been able to give rifles to only ten percent of its personnel and ammunition supplies were limited. The Japanese 40th Army, responsible for the defence of the V MAC and IX Corps landing areas had only 186 trucks, forty-six armoured cars and sixty-four 'other' vehicles. Half of these were inoperable due to lack of maintenance and the remainder had only limited range due to a shortage of fuel. Therefore terrain in the IX Corps area favoured the defenders but the observers found that the Japanese had done little to capitalise on this advantage, for little had been done to site gun positions and prepared defences on the enfilade positions of Kaimon Dake on the right of the landing beaches and the rocky peninsula to the left of the landing beaches or even on the rocky lowland immediately behind the beaches. In fact, the IX Corps observers saw the terrain and the lack of a decent road network as their chief obstacle. The black, hard volcanic sand on the beaches would allow 'dry' landings but the beach was backed by a continuous, tree-covered bluff, between 20 and 40-foot high. The only exits were narrow footpaths, thus requiring a major engineering effort to cut exits through the bluff and egress routes for the assault divisions from the beach. After that, the assault troops faced an intricate pattern of terraces interspersed with deep gullies, narrow ridges, foothills and villages. Such terrain would have made formidable natural defensive positions and only really required a reasonably equipped force to position itself appropriately to make the area a natural fortress. It was in this terrain that IX Corps had to establish a beachhead and develop attacks in two directions, one division moving towards the Imperial Japanese Army airfield at Chiran ten miles to the north, the other westwards across the peninsula towards the eastern shore of the Kagoshima Wan. Despite the rugged terrain, the IX Corps observers concluded that the weakness of the Japanese defences would have allowed IX Corps to fulfil its mission. Chances are, overwhelming American air, naval and land power would have prevailed, as it had done at Luzon, Iwo Jima, Okinawa and the Mariana Islands. Japanese defenders were very numerous but lacked prepared defences, adequate resources, mobility and lacked extensive training. The rough terrain of Southern Kyushu would have restricted the US ability to manoeuvre, slowed progress and probably caused the operation to fall behind schedule but would have handicapped the Japanese ability to move reinforcements into the battle area.

As mentioned previously, the basic idea behind the Pacific drive was that each operation would advance Allied forces towards their ultimate goal of Japan but also provide bases for subsequent operations. Just as Operation Iceberg brought Allied forces within striking range of Kyushu and from which planes based there could cover the whole of the island, so bases on Kyushu would allow aircraft to reach the Kanto Plain on Honshu. Following the invasion of Kyushu, a massive construction effort would begin to turn the southern portion of the island into a giant air, naval and ground base for the Allied forces marshalling for finishing the war against Japan. Aircraft could reach most targets in Japan while ground and naval forces could stage for Operation Coronet, the assault on Honshu, while the Navy could also reach the Tsushima Straits and complete the blockade of the Japanese Home Islands. Such an effort would have been immense, requiring tens of thousands of engineers. Indeed, a brigade of such troops would accompany each corps onto the beaches. Immediately behind the assault troops, even as the fighting continued, additional construction battalions would arrive to start the largest base-building effort yet seen in the Pacific, a theatre that required enormous construction and service resources, given the disparate and scattered nature of the objectives and lack of infrastructure. In the Sixth Army troop list, engineers numbered some 117,500, accounting for twenty-one percent of the army's strength and that didn't include navy construction units or other support personnel. All the combat units slated to take part in Olympic were already in the Pacific, but a large number of engineer and support units would have to be redeployed from Europe. Such redeployment would involve, engineer, construction, medical, port and quartermaster units, making up about fifty percent of the units supporting Sixth Army. Most would arrive through the Philippines and stage through Luzon. Others would arrive will the roll-up of units based in New Caledonia, the Solomons and New Guinea with others still coming straight from the continental USA. (Troop List of Service Troops to Stage through Luzon, 19 July 1945, RG 338, Box 59, Sixth Army G-4 Decimal File, 1943 – 46, File 4, WNRC)

Planners envisaged three giant base complexes, capable of supporting over 720,000 troops and 2,800 aircraft. The Sixth Army would begin construction as soon as it was feasible to do so and then on X-Day+30 turn over the construction effort to ASCOM "O", while CINCPAC worked on the naval facilities. Each base would include camps to house soldiers, covered storage facilities, bulk petroleum storage, hospitals and shops. Every effort would be made to repair and upgrade the existing road infrastructure as well as airfield construction or repair, the priority to be given to all-weather runway and command and control buildings. Dispersal areas and hardened shelters for aircraft would come later. (Engineer Annex to USAFPAC Operations Instructions No. 1, 20 June 1945, RG 338, Box 193, Sixth Army Engineer Section Plans and Operations, 1943 – 45, WNRC) Three base commands would be responsible for the construction and all the logistic support for the forces in their area, receiving, storing and issuing all the supplies for the units concerned. Additional supplies for Olympic would come directly from the USA with ships being pre-packed on the west coast. Each ship would be loaded with standard quantities of commonly used items, such as food, clothing, medical supplies, spares etc. Others would have the bulk items, such as ammunition, fuel and construction materials. These ships would start to leave the USA at intervals, weeks before the operation was to begin and be held in harbours all over the western Pacific (such as Okinawa) before being sent forward to the assault beaches as needed. Base Commands would also be responsible for the short-term hospitalisation of casualties after X-Day+15. By X-Day+90, the base commands would have had the facilities to take care of most casualties, except those requiring more than thirty days of hospitalisation. (Basic Logistic Plan, OLYMPIC, in Fifth Air Force Logistical Plan for Operation OLYMPIC, US Air Force Historical Center, Bolling Air Force Base, Washington DC) The largest of these commands would have been Base 1 in the Kagoshima area, built to house some 400,000 troops. This base would have served all the facilities in the Satsuma Peninsula, including the V MAC area. Four installations would have been built to hold 245,000 barrels of fuel, port facilities would have been expanded to house fourteen lighter craft, four small ships and ten Liberty ships simultaneously. Pipelines would have been laid to serve the facilities in the southern end of the peninsula and the combat units covering the stopline, running from Kushikino to Sendai and from Kagoshima to Kajiki. Engineers would build 900,000 sq ft of covered shop space, 1.8 million sq ft of covered storage and by X-Day+135 would have built hospitals totalling 13,250 beds. Base 2 would house 185,000 troops and be built in the Shibushi-Kanoya-Miyakonojo area. To serve the many airfields in this area, bulk fuel storage facilities able to hold 497,000 barrels would have been built, along with pipelines running from the terminal at Shibushi to Kushira, Kanoya and Takasu in the west as well as Iwagawa and Miyakonojo in the north. Dock facilities at Ariake Wan were limited but once Kagoshima Bay was opened, ships could dock across the bay in Takasu near Kanoya. Plans called for 1.25 million sq ft of covered shop and storage space and by X-Day+135, 15,500 hospital beds. In addition to all this, around 45,000 sq ft of headquarters space had to be provided in the Shibushi area to hold MacArthur's forward headquarters and its 1,000 personnel as well as an additional twenty-five buildings to hold communications and signals equipment. Base 3, located in the Miyazaki area, was to be the smallest of the three bases due to the lack of covered or sheltered anchorage facilities, only accommodating some 135,000 troops, housing bulk storage facilities for 121,000 barrels of fuel, 4,500 hospital beds and 150,000 sq ft of covered shop and storage space. 1, 20 June 1945, RG 338, Box 193, Sixth Army Engineer Section Plans and Operations, 1943 – 45, WNRC)

Nimitz himself planned to build a number of naval installations in the southern portion of Kyushu. The largest was planned for Takasu on the eastern side of Kagoshima Bay, near Kanoya Airfield. At Takasu, the Navy would build an artificial harbour, with piers to handle ten attack transports and a tanker simultaneously. The base would also be capable of repairing small craft, patrol boats and landing craft as well as having storage facilities of commonly used supplies such as ammunition and fuel. Covered storage of 1 million sq ft would hold supplies for servicing the fleet. Nearby, the Navy would adapt one of the airfields at Kanoya to accept planes from the Naval Air Transport Service. Smaller and more specialised facilities were planned for Uchinoura, a small bay on the southern side of Ariake Wan, at the mouth of Manose Gawa near the southern end of Fukiagehama as well as at Yamagawa ear the mouth of Kagoshima Bay. Uchinoura would serve naval forces operating near Ariake Wan, Manose Gawa would allow tankers to unload their fuel to the nearby marine air bases and Yamagawa would become a PT-boat base. All these facilities were to be operational by X-Day+120. (CINCPAC Operations Plan, OLYMPIC, USMC Geographic File, Japan, Box 50, Folder B1-1, WNRC)

The massive construction effort demanded by the consolidation of the American hold on Kyushu and the preparation of bases to hold the forces that would undertake Coronet placed great demands on engineering resources available to the planners. Sixth Army predicted unprecedented demands for engineers to support combat operations due to the poor roads and difficult terrain on Kyushu. When that demand was combined with the needs of the base building effort, there were simply not enough engineers to go around. Sixth Army Engineer Brigade General S D Sturges Jr was concerned that the construction programme outlined for the first sixty days of Olympic were far too ambitious. Even without any fighting, he argued, the programme timetable could not be met. He thought that the number of engineer units would have to be double in order to complete the programme to schedule. FEAF also complained that that the number of engineer construction units allocated to airfield construction was inadequate to allow the build-up of airpower laid out in the Olympic plans. General Kenney urgently requested that additional engineer effort be allocated to air force projects, a requested that was rejected by AFPAC citing that there would be a shortfall in engineer and construction resources in the objective area. (Memo, Sixth Army Engineer to Chief of Staff, 3 June 1945, RG 338, Box 59, Sixth Army G-4 Decimal File, 1943 – 1946; Letters, Allied Air Forces to CINCAFPAC, 3 August 1945 and CINCAFPAC to CGFEAF, RG 338, Box 191, File No. 5, Sixth Army Engineer Section Plans and Operations, 1943 – 1945, WNRC) In June and July, an ongoing debate started between Sixth Army staff and MacArthur's staff over the allocation of engineer units. The Sixth Army staff wanted to retain some engineer units for use in combat operations while AFPAC staff wanted to use them in the construction effort. The initial Olympic troop list assigned two heavy construction engineer groups and several construction battalions for use in building roads and bridges along the army's lines of communications. AFPAC suggested that these units revert to ASCOM 'O' after X-Day+30 for use in base construction. Sturgis, and his assistant Colonel John C B Fuller, argued that it was "inconceivable that an army commander would be denied these units on a major operation." They also threatened that they would urge General Krueger to go directly to General MacArthur. If Sixth Army failed to get adequate engineer support, it would suffer materially. (Memo, Colonel Elliott to General Krueger, 28 June 1945, Sub: Command Request for Construction Groups and Construction Battalions for Olympic, RG 338, Box 196, Sixth Army Engineer Section Plans and Operations, 1943 – 45, WNRC) For two weeks nothing happened, forcing Krueger to write to General MacArthur. He argued that the Luzon Campaign had proved the desirability, if not necessity, of attaching heavy construction groups to forces in the field. Olympic, he argued, would require far more heavy construction resources be made available for tactical operations than any previous operation. Ultimately, the issue remained unresolved as the war ended but highlighted an area of logistics and resource management that had plagued much of the Pacific War – the need to build huge bases with only limited resources and manpower. However, the central reason for undertaking Olympic was to acquire bases for the movement of air forces forward from the Philippines and Okinawa in order to support the final phase of the Pacific Campaign – Operation Coronet, the attack on Honshu. Both the Japanese Army and Navy had built bases on the southern part of Kyushu and these bases became important objectives in the planned assault. FEAF, consisting of the Fifth, Seventh and Thirteenth Air Forces and supported by the First Marine Air Wing supporting V MAC was responsible for the direct air support of Olympic, a mission they could not do if they stayed in the Philippines. Even before the Tenth Army began its assault on Okinawa (Operation Iceberg), General Kenney and his staff had began to look at the possibility of deploying forward to new bases on the island and its neighbours in the Ryukus chain. Even as CINCPAC and AFPAC reached agreement in June, a massive construction effort was underway on Okinawa as the air planners had found that Okinawa and the nearby islands were ideal for their needs. The planned bases on Okinawa would hold air groups form the Fifth and Thirteenth Air Forces, while the smaller islands of Ie Shima and Kikai Jima would hold units of the Seventh Air Force and First Marine Air Wing respectively. By 1st November, plans called for an air garrison of just over forty-eight air groups with forces moving forward from the Philippines in July with over 1,850 planes in place by 15 October 1945 which would not have included the aircraft of the First Marine Air Wing or the twelve groups of B-29s from the Twentieth Air Force. Despite the relative isolation of southern Kyushu and the relatively un-developed nature of the infrastructure, the Japanese had developed around twenty airfields in the area. The south of the island guarded the Tsushima Strait, the southern entrance to the Sea of Japan as well as shipping routes to the south of the Home Islands. There was a single base near Kagoshima, with two others near the head of Kagoshima Bay, another at Miyazaki, two towards the southern tip of the Satsuma Peninsula (at Tojimbara and Chiran) with a third being built at Byu near Matsunaga. The largest concentration however was spread across the Osumi Peninsula from the head of Ariaka Wan to Kanoya as well as north to Miyakonojo. These same locations would be developed and utilised for the arrival of the huge air garrison scheduled to support operations. (CINCPAC Operations Plan, OLYMPIC, USMC Geographic File, Japan, Box 50, Folder B1-1, WNRC)

The air plan called for the first units to arrive at Miyazaki and Shibushi on X-Day+2, and at Chiran near Kagoshima Bay on X-Day+7. The first units to arrive would be command, control, communications, air control as well as other service and support elements. Planes and pilots would begin arriving on X-Day+4. To ensure air superiority and the support of ground operations, fighters would arrive first with the medium and heavy bomber groups coming later. Approximately sixty days after the assault would have began, over forty air groups with almost 2,800 aircraft were to have been deployed. As these land-based planes arrived, they would replace the carrier planes supporting the ground operations and protecting the beachheads of the Sixth Army. Those planning Olympic envisaged three air complexes in southern Kyushu, each located in one of the base areas. The Miyazaki area would have seven-and-a-half groups deployed of the Fifth Air Force on two 7,000ft runways. The largest airfield complex would be created in the Shibushi-Kanoya-Miyakonojo area, with airfields at Shibushi, Kushira, Kanoya, Iwakawa and Miyakonojo holding twenty-four-and-a-half groups from Fifth, Seventh and Thirteenth Air Forces. An advance headquarters for FEAF would be established at Kanoya, while across Kagoshima Bay, the Japanese airfields at Chiran and Byu would be rebuilt with naval construction units to accommodate the five-and-three-quarters groups of the First Marine Air Wing and one group of naval search planes. (CINCPAC Operations Plan, OLYMPIC, USMC Geographic File, Japan, Box 50, Folder B1-1, WNRC; Fifth Air Force Tentative Shipping List No. 2 for OLYMPIC Air Garrisons, 30 June 1945, RG 338, Box 195, WNRC)

The Allied Plans (2): Coronet

The follow-on operation to Olympic was codenamed Coronet and was aimed at the Kanto Plain on the island of Honshu. The Kanto Plain is the largest level area in Japan, measuring some seventy miles across by ninety miles deep. The area is ringed by mountains to both the north and the west, some measuring up to 6,000 feet in height. Kanto, had a special place in the modern, post-Meiji Japan, as well as containing the economic and political centre of the Empire. Around half of all Japanese war industry was located there and in 1945, almost eighteen million people lived there, almost a quarter of the population. The key geographic feature is Tokyo Bay which opens up in the south to the Pacific Ocean, through the Uraga Strait, a narrow ten-mile wide opening located between two rugged peninsulas, Boso to the east and Miura to the west. Along the northern and western shores of the bay lie the large industrial and port cities of Tokyo, Kawasaki and Yokohama with the large naval base at Yokosuka just south of Yokohama, just inside the Uraga Strait. Looking at the area as a whole, two beaches approximately fifty to seventy-five miles east of Tokyo were suitable for amphibious operations. Kashima and Kujukuri are long open areas of flat sand with broad, shallow slopes but are quite a distance from Tokyo. In a better position strategically, is Sagami Beach, a grey volcanic sand beach (similar to the ones on Iwo Jima) that lies at the head of Sagami Wan and directly south of Tokyo. Kashima, the northernmost of the two Pacific-facing beaches, is backed by a major river and other water barriers to military manoeuvre – any force landing there would face a long drive towards Tokyo and southwest towards the western shore of the Boso Peninsula. Kujukuri Beach is closer to the Boso Peninsula and stretches about thirty-one miles (50 km) between Chosi in the east to Ichinomiya in the west. Similar in many ways to Omaha Beach in Normandy, it is compartmentalised with high steep bluffs coming down to the water's edge at either end. The terrain remains flat for about four miles (7 km) with a line of steep bluffs suddenly rising, again, not unlike Omaha Beach but further from the sea. It was on that line of bluffs that the Japanese sited their main defences. The ridge rises to about fifty metres and forms an almost uninterrupted wall from Ichinomiya to Chosi, but is cut in a number of places by narrow valleys with roads leading to Tokyo. On these the Japanese had placed strongpoints of company and battalion size, builts onto what high ground was available with antitank guns sited to fire on the roads. All round the base of these hills, the Japanese had dug tunnels, many passing through the hills so that the firing positions on the forward slopes could be served from positions on the reverse slopes. At regular intervals, the Japanese also dug rooms off the tunnels to act as barracks, storage areas and command posts with wells being dug to catch fresh water. In addition, the Japanese placed an entire regimental system of underground strongpoints near Togane and at the lower end of Kujukuri Beach within the bluffs near Ichinomiya, tunnels were dug through solid rock to link heavy gun positions that could fire straight up the beach for several thousand yards. The positions would have been extremely difficult to take out with naval gunfire or aerial bombardment. Meanwhile, Sagami Beach today has a great deal of industry and commercial premises located around it but in 1945, this was much less concentrated. The beach was firm smooth sand and did not any troublesome dunes backing onto it. The actual usable beach is approximately nine miles (14 km) long with the western section being the end of the Sagami River valley, now industrialised, then agricultural, that runs like a motorway into western Tokyo. For over eighteen miles (30 km) this valley provides a flat natural corridor suitable for highly mobile forces but is eventually obstructed by heights rising above 150m. On the eastern end of the beach, a thirty metre high ridge blocks progress into the interior after a couple of miles. In terms of defending the Kanto Plain, Sagami Beach was the Achilles Heel. Kujukuri Beach was ideally suited to amphibious landings but the attackers would have faced a number of obstacles including bluffs blocking movement into the interior after several miles, Japanese defences were quite well developed, there was a lack of a good port in the area and the terrain favoured Japanese counterattacks. At Sagami, the Japanese would not have forces in the immediate area to counterattack as they were going to consider the landings at Kujukuri as the primary threat. The terrain around Sagami would have favoured US mobility, firepower and aided US airpower and naval gunfire support.

On the Kanto Plain, the United States would seek to inflict a decisive defeat on the Imperial Japanese Army in the "heart of the Empire" or if that did not occur, gain an advantageous position with which to continue the conquest of Japan. The plans for Coronet were not as advanced as for Olympic and were only in draft form when the war ended. On the day of Japan's surrender, MacArthur's AFPAC Headquarters published the first draft (Outline Plan for the Invasion of the Kanto Plain, RG 218, CCS Honshu (7-19-44), NARA; AFPAC Staff Study CORONET, 15 August 1945, RG 165, NARA) of the Coronet staff study, "as a matter of interest only and for the completion of files of all concerned." (Skates, p. 201) Planning however, had started in mid-1943 when Allied forces were still thousands of miles away from Japan. Planners had recognised the importance of the Kanto Plain in any future invasion of the Japanese Home Islands but also a long struggle to gain bases for the bombing campaign against Japanese industry as well as the necessity for the destruction of the Imperial Japanese Navy and any invasion of the Kanto Plain would require a firm base in either Kyushu or Hokkaido from which to launch a final, decisive assault against Honshu. These studies (Appreciation and Plan for the Defeat of Japan, JWPC 46/5, 9 July 1943, RG 218, NARA) by necessity lacked detail, but such planning got underway in mid-1944 by the Joint War Plans Committee. The Joint Chiefs of Staff intended to present the British with a new invasion strategy at the Octagon Conference in Quebec in September 1944. The early plans for Coronet laid out an ambitious undertaking involving three armies and twenty-five divisions (Eighth Army, CORONET Operation, G-3 Plans (Invasion of Japan), May-June 1945, RG 407, Box 2836, WNRC). An army group headquarters, probably Bradley's 12th Army Group Headquarters then in Europe as no equivalent structure existed in the Pacific, would command the invasion. On Y-Day, the first army would land on Kashima Beach opposite Mito and with an armoured corps in the lead, would drive across the northern Kanto Plain and seal of the entrances to the plain. The second army would simultaneously land on Kujukuri Beach, occupy Choshi and advance across the Boso Peninsula to clear the eastern shore of Tokyo Bay. On Y-Day+30 the third army would land on Sagami Beach, seal off the mountain passes to the west and seize the Miura Peninsula and Yokosuka Naval Base. After achieving these objectives, the three armies would simultaneously launch a final assault on Tokyo. During the summer of 1945 in both Washington and Manila, the plans for Coronet gradually evolved. In early May, the planning staff in Washington DC issued a revised edition to their earlier plans (Outline Plan for the Invasion of Japan, Honshu (7-19-44), RG 218, CCS 381, NARA). Recognising the difficulties faced with the redeployment of forces from Europe, the planners now scaled down the size of Coronet by suggesting two armies would suffice instead of three, with assaults on just the Kujukuri and Sagami beaches. The number of divisions was reduced from twenty-five to twenty-three with twenty in the assault and three in reserve. There would be eighteen infantry divisions and five armoured divisions. The assault on Kujikuri would be secondary with Sagami being the primary operation. There was also no mention of an army group headquarters commanding the overall operation. On the day of the assault, one army would land at Kujikuri with a corps of three infantry divisions at Katakai and a corps of two infantry divisions at Ioka, just to the west of Choshi. The force landing at Katakai would drive directly westwards and clear the eastern shore of Tokyo Bay while those landing at Ioka, after seizing Choshi, would realign themselves on the right flank of the other corps. By Y-Day+35 there would have been nine divisions (including two armoured divisions) ashore. By Y-Day+10, the Sagami force would have begun putting forces ashore in the Oise-Katase area of Sagami beach. The planners hoped that the earlier landing at Kujikuri would draw away some, if not all, of the Japanese reserves and counterattack forces. To further reinforce this idea, convoys carrying two divisions would conduct demonstrations off Kashima beach on Y-day+7 and 8. These divisions would then proceed to their landings on Sagami beach on Y-Day+14. Thus the main attack, totalling eight infantry and three armoured divisions by Y-Day+30, could advance towards Tokyo after clearing the Miura Peninsula, Yokosuka and Yokohama.

As the JWPC were refining their draft outlines, MacArthur's staff was also busy putting together their own strategic plan for Operation Downfall. The first edition was released only three weeks after the JWPC issued their revised draft. Coronet, as outlined in Downfall, differed significantly from the JWPC plan. Downfall retained the earlier three-army, twenty-five division setup. Eighth Army and Tenth Army would lead the assault with a combined force of fourteen divisions. First Army, redeployed from Europe, would follow-up with ten divisions. A single airborne division in Kyushu (presumably 11th Airborne Division) would serve as AFPAC reserve. This plan (AFPAC, DOWNFALL, Strategic Plans for Operations in the Japanese Archipelago, 28 May 1945, RG 15, OPD 350.05, NARA) also contained no reference to an army group-level headquarters. Even as this planning progressed, some questioned the adequacy of air support from the bases in Kyushu. Only long-range fighters could reach the Kanto Plain from bases in Kyushu and unless closer airstrips were found, the majority of close air support would have to come from carrier-based aviation. The JWPC was asked to study the feasibility of conducting small landings to gain airbases closer to the Kanto Plain. The report (Operations Preceding CORONET, JWPC 359/1, RG 218, NARA) was ready by early June and looked at the area around Sendai in northern Honshu, sites around Shikoku, the Hamamatsu coastal lowlands between Tokyo and Nagoya and the Izu Islands, an island chain just to the south of Tokyo Bay. The report eventually rejected all of them, indicating that it thought the possible costs of these assaults were likely to be disproportionate to the advantages gained. The Japanese, it was judged, would react violently to the intermediate assaults and the casualties taken would be high producing only slight gains. Some of them would require quite large forces and so delay Coronet. The report concluded that Kyushu-based and carrier-based airpower, properly coordinated, should furnish adequate fighter support for Coronet. With these outline plans available, AFPAC set to work producing a full staff study for Coronet. When the war ended, MacArthur's planners had just finished the first draft and it was published in an incomplete form (AFPAC Staff Study CORONET, 15 August 1945, RG 165, NARA). Like all military plans, Coronet would undoubtedly have been subject to revision with units being swapped in and out, missions changed, phase lines adjusted, landing timetables adjusted etc. However, what this staff study did contain was a unit roster, a scheme of operations and an assessment of the Japanese reaction. This initial staff study posited that the Coronet assault would be undertaken by two field armies, the First, redeployed from Europe, and the Eighth. For unknown reasons, the Tenth, formed for the assault on Okinawa (Operation Iceberg) had been dropped from the troop list. Eighth Army had been the second field army activated in MacArthur's Southwest Pacific Area. Formed in June 1944 in the USA, the Eighth Army headquarters deployed to the Pacific in September that year and General Eichelberger, who had been with MacArthur since the beginning of the Pacific War, took command. The army spent the remainder of the war mopping up after Sixth Army in Leyte and Luzon, conducting countless small amphibious operations to liberate the central and south Philippines. First Army had fought its way across Northwest Europe from D-Day to VE Day under General Omar Bradley and later General Courtney Hodges. It is likely that First Army's experience of employing and coordinating large mechanised forces on the European Plain, experience that no other army headquarters in the Pacific had, was a factor in their inclusion in the line-up for Coronet. No army group headquarters would command the two armies; instead an advanced headquarters group from MacArthur's AFPAC would command the forces on the Kanto Plain.

In this initial draft staff study, for the assault, First Army would command two corps, the XXIV Corps made up of the 7th, 27th and 96th Infantry Divisions, as well as the III Amphibious Corps, comprising the 1st, 4th and 6th Marine Divisions. The XXIV Corps had not been created until March 1944 but had already fought through two tough Pacific campaigns – those of Leyte and Okinawa – with all three divisions participating in both campaigns. Of the Marine Corps' six divisions, three were scheduled to take part in Operation Olympic (2nd, 3rd and 5th) while the other three were scheduled to participate in Coronet. III Amphibious Corps had landed at Guam while V Marine Amphibious Corps had landed at Saipan and Tinian in July 1944. The 1st Marine Division was the most senior formation and had fought all the way from Guadalcanal through Peleliu to Okinawa. The 4th had fought on Iwo Jima while the 6th had fought on Okinawa. Eighth Army would command three corps – X, XIII and XIV. The X Corps had been formed in the USA in May 1942 and deployed to the Pacific in July 1944 to take part in the fighting for New Guinea and fought through the campaign for Leyte. Of the three divisions, the 37th was the most experienced, having fought on New Georgia, Bougainville and Leyte. The 24th had fought on Hollandia, New Guinea and Leyte and for the remaining months of the war was engaged in clearing the southern Philippines. The 31st trained in the USA from the time it was federalised (November 1940) until it deployed to New Guinea to continue training and finally entered combat at Morotai and in April and May 1945, helped to clear Mindanao. XIV Corps would command the 6th, 32nd and 38th Infantry Divisions. The corps had been sent to the Pacific in January 1943 to command the forces on Guadalcanal once the marines had been augmented by two army divisions, and also fought on New Guinea and Bougainville. It took part in the assault at the Lingayen Gulf under Sixth Army in January 1945 and continued to take part in the Luzon campaign until August 1945. The divisions assigned to the corps were veteran divisions, the 6th was a regular army formation that entered the Pacific War at Wake Island in 1944 and participated in the Luzon campaign from the start, mostly serving under XIV Corps. The 32nd had been sent out to Australia in May 1942 and took part in the fighting for Buna from November 1942 to January 1943. It also fought in the campaign for northern New Guinea in 1944 as well as taking art in the Leyte and Luzon campaigns. The 37th, a National Guard division like the 32nd, had seen its share of fighting on New Georgia, Bougainville and the attack at Lingayen. Of the five corps slated to take part in the initial assault, the XIII, along with its two component formations, the 13th and 20th Armoured Divisions, was the only redeployed unit scheduled to take part in the opening phase. The corps had had experience of leading armoured forces across Europe, a skill lacking among the other corps headquarters as no armoured divisions were deployed in the theatre. Both armoured divisions had entered combat during the last stages of the war in Europe and suffered relatively few casualties.

On Y-Day+30, each army would receive an additional corps of three infantry divisions. When the staff study had been published, the corps headquarters had not been finalised but would have almost certainly had to have come from the forces in Europe. The six component divisions would have also had to have come from forces redeployed from Europe and were slated to include the 5th, 44th and 86th Infantry Divisions for the First Army, and the 4th, 8th and 87th Infantry Divisions for the Eighth Army. Likewise, with the exception of the 11th Airborne Division, all AFPAC reserves would be made up from redeployed units. The 97th Infantry Division, slated to be the floating reserve on Y-Day had entered combat late in the Northwest Europe campaign. The AFPAC follow-on reserve would contain three veteran infantry divisions – 2nd, 28th and 35th. The AFPAC strategic reserve would contain another three veteran divisions, the 91st which fought in Italy, as well as the 95th and 104th. While the plans failed to identify specific corps and corps commanders, Marshall made it plain to his assistant, General Hull, that he had no intention to seek MacArthur's personal approval before redeploying corps headquarters and commanders to the Pacific. Instead, he sought to select those who were acknowledged as the best from the ETO and send them out. If MacArthur had any specific objections, he could make them known at that time. Marshall suggested: III Corps under Major General James A Van Fleet; V Corps under Major General C R Huebner; VII Corps under Lt General J Lawton Collins; XIII Corps under Alvan C Gillem; and XVIII Corps under Major General M B Ridgeway (Memo, Marshall to Hull, 28 May 1945, Verifax 1193, Item 2288, Marshall Library; Message, Hull to MacArthur, 29 May 1945, Verifax 1193, Item 2799, Marshall Library). Planning documents for the naval and amphibious phases of Coronet had not been drafted when the war finished but it is evident from the AFPAC staff documentation and plans that the Navy's role in the operation and the relationship between Nimitz's staff and MacArthur's staff would have been very similar to that of Olympic. CINCPAC would plan for the naval and amphibious phases while AFPAC would plan for the land campaign. It is likely that similar arrangements would have been made for the transition of command between the naval and ground commanders as the ground forces were established ashore. Naval and air bombardment of the objective areas would start from about Y-Day-15. On Y-Day itself, the two field armies would make simultaneous landings and although the preponderance of force was with Eighth Army, in the initial staff study, neither assault was designated as a main one. First Army would land elements of the XXIV and III Amphibious Corps near the middle of Kujukuri Beach. The 7th and 27th Infantry Divisions as well as the 1st and 4th Marine Divisions would land and establish a beachhead. On Y-Day+5 the 96th Infantry and the 6th Marine Divisions would then come ashore. First Army would face three major tasks once they had come ashore. Firstly, forces would move south and west across the Boso Peninsula to tackle the defences guarding Tokyo Bay. Forces would also move northwards towards Chosi in order to secure this small port. An open corridor leads northwest towards Tokyo, bounded by Chiba and the northern shore of Tokyo Bay on its western side, as well as two lakes (Imba-Numa and Tega-Numa) to the north. First Army was to advance towards Tokyo using this corridor. Eighth Army would land on the beaches at the head of Sagami Bay with elements of X Corps and XIV Corps. The initial units to land would be the 24th and 31st Infantry Divisions (X) as well as the 6th and 32nd Infantry Divisions (XIV). After establishing a beachhead, Eighth Army would move eastwards clearing the Miura Peninsula and capture the Yokosuka Naval Base. On Y-Day+10 the XIII Armoured Corps would land and then drive straight north up the Sagami River valley, establishing blocking positions north of Tokyo from Kamagaya to Koga with XIII Corps being ready to advance towards Tokyo as necessary while other elements of Eighth Army were to capture Yokohama and assist First Army's capture of Tokyo.

The logistic plans for Coronet (Logistical Plan for the Invasion of the Kanto Plain, JLPC 47/10, 8 May 1945, RG 218, NARA) foresaw the same kind of massive base development that would start after the initial stages of Olympic. Very soon after the assaults had taken place, construction would begin on air, sea and supply bases to support operations. From these bases, almost every area of any importance could be brought under air attack or if the situation required, amphibious assault. The naval base at Yokosuka would an important asset in tightening the naval blockade but the planners emphasised the importance of clearing the shores of Tokyo Bay to provide port facilities as well as the port of Chosi being an early objective. Its capacity was too small to supply the entire army so until the Uraga Straits could be cleared, the majority of the ground forces supply would have to come in over the beaches, a vulnerable situation especially at Kujukuri where Pacific storms could interrupt supply at any time. Overall however, logisticians foresaw few problems in supporting the operation. Although there was concern over the possibly limited amount of supply that could move through Sagami and the possibility of supply being interrupted due to storms, given good weather, there was confidence that both armies could be supplied across the beaches. As with Olympic, a great deal of the supply would initially come from ships that had been packed with pre-arranged loads. The road communications in each area were adequate to get supplies forward and the early capture of Yokohama would provide adequate port capacity to supply the Sagami Beachhead. The greatest problem in this regard was fuel. Coronet was judged to require around 22 million barrels (924 million gallons) of fuel in the first thirty days. Such consumption would require the use of every tanker then under American control. The planners however wanted some form of insurance against Pacific storms. Taking a lesson from the famous 'Mulberry' artificial harbours built for the Normandy invasion, planners were going to use an artificial harbour on Kujukuri Beach, to be placed at either Katakai or Ioka to handle freighters and Liberty ships. Beginning to Y-Day+2, a two-mile long breakwater would be constructed over a mile out to sea with angled breakwaters made up of sunken vessels, wrecked tanks and other heavy objects extending to the beach at either end. Ships would enter through 600 foot openings in the side. Pontoon causeways would lead to the beach from Liberty Ship berths along the breakwater while LST wharves and lighter piers would be built on the beach. All would be scheduled to be complete by Y-Day+12. In both the Kujukuri and Sagami areas, large bases would be constructed, as in Olympic, for communications, equipment and supply storage, troop holding areas, facilities for Japanese POWs and detention camps for civilians. Hospital facilities alone would have beds for 42,750 casualties. Another 45,000 beds would be available in the western and central Pacific areas. Again, as in Olympic, the repair of Japanese air and naval facilities would have proceeded as soon as the ground forces had begun to move inland so that land-based airpower could be established as quickly as possible. By Y-Day+15, it was planned to have nine air groups operational and by Y-Day+30 to have over thirty groups operational on the Kanto Plain. As in Olympic, maximum use would have been made of existing Japanese airfields, including those in the Sagami area at Atsugi (later to be come the base from which U2 spy planes were flown), Fuchu, Hara-Machida, Kawagoe and Odawara. Those in the Kujukuri area included Chosi, Hikata, Katori, Kioroshi, Miyakawa, Mobara, Narita and Naruto. These land-based planes would release the carriers to widen the air war throughout Honshu and Hokkaido. They would also be in a position to support further amphibious landings in central and northern Japan should the Japanese not surrender after landings on the Kanto Plain.

As outlined previously, the planners of Coronet foresaw that they would not be able to completely hide the objectives and preparations for Coronet from the Japanese so set about trying developing a plan (Staff Study of Cover and Deception Objectives for CORONET, JWPC 190/16, 26 July 1945, RG 218, NARA) to deceive the Japanese as to the exact timing and landing places of Coronet, and by threatening other places around Japan hoped to keep the Japanese from reinforcing their troops in Honshu and keep garrisons scattered around the Home Islands. The story to be ‘leaked’ was that the United States needed additional bases to encircle Honshu and wear down Japan’s military forces by bombing and blockade before landing on the Kanto Plain. The story would emphasise the need to redeploy forces from Europe which wouldn’t be ready to invade until early 1947 and in the meantime, the United States would conduct smaller operations to seize such bases to support the operation as needed. Three objectives, which had indeed been debated as to alternative targets to Kyushu would continue to be emphasised in these deception plans. These were the Pusan area of southern Korea, Shikoku and Hokkaido. Even after Y-Day, planners hoped that threats to these areas would stop the Japanese from diverting major forces to Honshu. After the start of Olympic, planners to start to emphasise the threat to Korea so that the Japanese would believe that there would be an assault on the Pusan area of southern Korea around the time of Y-Day+60. If successful, it could prevent the Japanese from shifting troops from the Korean peninsula back to Japan. The threat to Shikoku which would begin even before Olympic began, would try and convince the Japanese that the island was the next target after Kyushu – that landings there were only the first step in establishing a ring of bases around Honshu. While the threat obviously could not be continued after Y-Day, the planners hoped it might convince the Japanese to shift forces to Shikoku before Coronet. Finally, the imagined build-up in the Aleutians would be continued to heighten Japanese fears over an invasion of the Kurile Islands, Hokkaido or both, especially as the Soviet Union might enter the war on the Allied side. Planners hoped that this threat could tie down forces until around Y-Day+90. Japanese intelligence would be encouraged to believe these threats through such methods as information leaks to American newspapers, adverts for Korean experts and interpreters, spreading rumours among Coronet follow-on troops that they were heading for Shikoku or Korea, planes dropping warning leaflets alerting Koran guerrillas or telling Japanese civilians to avoid certain areas of Hokkaido or Shikoku, false documents would be planted, for example, a US headquarters in China would have a false campaign plan for Korea, radio traffic would be used in a code that was know to be compromised, dummy bases would be built in the Aleutians, dye markers dropped off the beaches of Hokkaido and obvious photo reconnaissance and bombing missions would take place on these areas. Tactically, the planners hoped to convince the Japanese that landing would take place on all three beaches at Sagami, Kujukuri and Kashima but only two – Sagami and Kujukuri – would be carried out. They would also make use of the planned follow-on forces, having these demonstrate against Kashima between Y-Day and Y-Day+9 and against Sendai on Y-Day+9 to fool the Japanese that additional landing would take place right along the coast of Tokyo Bay. These demonstrations would be preceded by air strikes and shore bombardment that would be of similar intensity to those used in real landings and use other methods such as simulating underwater demolition teams by dropping delayed action explosives and abandoned rubber dinghies, minesweepers laying smoke and pyrotechnics as well as radio traffic, all pointing towards and assault. All this activity would try and convince the Japanese that an assault would happen against Kashima on Y-Day+9 and against Sendai on Y-Day+10.

There is no doubt that the deception plans for Coronet were elaborate and expensive and would have confused the Japanese as to the grand designs the Americans had. By this stage in the war however, it was less important for the Japanese to know the grand design than to fight the immediate battle. They had limited and dwindling resources, with only a small capability to move their forces around on a strategic basis. Like the Americans, they saw the Kanto Plain as crucial to the Empire and thus any battle fought there would be decisive. Other areas would have to fend for themselves and thus the great concern upon which the Americans based their deception plans – that the Japanese would move forces onto the Kanto Plain – was an unlikely prospect, American airpower and the Japanese lack of strategic mobility would have seen to that. Intelligence analysts for the Joint Chiefs of Staff began in July to look at the Japanese ability to defend the Kanto Plain. Their conclusions (Defensive Preparations in Japan, 2 August 1945, JIC 311, RG 218, NARA; Japanese Reaction to an Assault on the Kanto Plain (Tokyo) of Honshu, JIC 218/9, 10 July 1945, RG 218, NARA) were very different from the post-war predictions of a suicidal Japanese defence exacting an unacceptably high cost. While the analysts recognised the last-ditch mentality of the Japanese command and understood that the operation would not be a walkover, they assessed Japanese defences as considerably less formidable as has been generally thought. Japanese air power was a major concern for the planners of Olympic, particularly the massed use of Kamikazes. That prospect was less daunting for the planners of Coronet as whether they made a conscious decision or not, the Japanese build-up of air and ground combat power in Kyushu during the last month of the war made it clear they would fight the decisive battle in southern Kyushu and then worry about the Kanto Plain afterwards. American intelligence believed that the remaining Japanese air and naval power, both conventional and suicide units, would be largely expended during Olympic and no more than around 2000 aircraft would be available for Coronet. With a serviceability rate of around 20 percent, they would only be able to launch around 100 sorties a day before being destroyed totally after several days. The IJN would be even weaker and limited to a few attacks by boats, midget submarines, kaitens and destroyers. To most analysts, the Japanese ground forces presented the central threat to the invasion, yet even here, the threat here was adjudged to be formidable but not impossible. Around thirty-four regular divisions and twelve depot divisions would be available for the defence of the Home Islands. After the invasion of southern Kyushu, the Japanese would find it almost impossible to bring over reinforcements from the continent and approximately ten divisions would be immobilised in northern Kyushu. On Y-Day, the Japanese would have in the region of nine regular divisions and three depot divisions deployed on the Kanto Plain under the command of the Twelfth Area Army. Three were deployed to defend the Kashima-Kujukuri beaches, two to defend Sagami beach and four held in reserve just north of Tokyo. While reinforcements were available from other areas of Japan and could probably reinforce the Kanto Plain prior to Coronet, once the invasion had begun, American airpower and the vulnerability of the road and railways leading into the Kanto Plain would reduce the ability of the Japanese to move troops. The analysts concluded that peak defensive strength would not exceed twelve to fourteen divisions.

When the war finished, American planners had given little thought as to a strategy for sustained operations should Coronet fail to produce a Japanese unconditional surrender. In preparing the Joint Chiefs for the Potsdam Conference, the Joint Planning Staff (on their own initiative) produced recommendations. They advised the Joint Chiefs to avoid any discussion of post-Kanto Plain operations with the British and the Soviets. Then, in a briefing paper, they outlined discussions that had been going on in relation to operations following the invasion of Honshu. Their suggestions were that the blockade should tightened and bombardment expanded from bases on the Kanto Plain and Kyushu, to gradually expand the territory held, launch additional amphibious operations to seize other critical areas. There is little evidence to suggest the Joint Chiefs or the Joint Planning Staff looked at how to force the almost two million Japanese soldiers on the Asian mainland to surrender, beyond relying on the Soviets to deal with Japanese forces in China, Manchuria and Korea, while the British continue offensive operations in Southeast Asia. No suggestions appeared that committed large-scale US forces to action on the Asian mainland but the possibility remained that US forces would have to carve out enclaves along the Asian mainland in order to supply Chiang Kai-shek’s Nationalist Army. Certainly, more detailed plans and studies would have to have been undertaken if the war had kept going and a few such plans had begun to appear in the last stages of the war (Operations following Invasion of Kanto Plain (Broad Plans), JCS 1417, 10 July 1945, in CCS 381 POA (4-21-45), RG 218, NARA). In May 1945, the Joint Intelligence Committee prepared a study on Japan’s military, economic and political capabilities for the Joint War Plans Committee. By mid-1946, the planners concluded (Operations Following Kanto Plain, JIC 286, 14 May 1945, in CCS 381 POA (4-21-45), RG 218, NARA) that the Imperial Japanese Navy would be incapable of effective defensive action with only a few cruisers, destroyers and submarines in hiding. Similarly, Japanese airpower would have been practically destroyed with just a few formations dispersed and disorganised. After Coronet, the Japanese ground forces would be the most formidable threat. Discounting isolated forces bypassed in the Pacific and forces in Indochina, the planning staff thought there were still fifty-four to fifty-nine divisions (totalling 1.9 to 2.15 million men). Around thirty-three of these (1.2 million men) were in China, Manchuria and Korea. Another five divisions (170,000 men) would be trapped on Formosa. Troops in the Home Islands would not it was thought, by mid-1946, exceed the equivalent of fifteen divisions (500,000 men) with two deployed on Sakhalin and the Kuriles, another eight to ten remaining in northern Kyushu and another three to five divisions guarding the passes out of the Kanto Plain. Another ten depot divisions (unorganised, poorly equipped and largely untrained) would be scattered around the Home Islands.

Analysts believed that located on the Kanto Plain, was twenty-two percent of Japan’s armaments industry and sixty-five percent of its electronics industry. They predicted that by mid-1946, the production of heavy armaments would have been reduced to a fraction of the level reached in 1945. Still, by cannibalising unserviceable equipment and dispersing production centres, Japan would still be able to produce significant amounts of light weapons. Perhaps more importantly, by mid-1946, the increasing impact of the air and naval blockade would have almost completely stopped the import of raw materials, thus forcing the Japanese to draw on stockpiles to keep industry working. Due to the same Allied air and naval power, the Japanese would find it increasingly difficult to move the remaining stocks of raw materials around the country. Raw material production on the Asian mainland would be less affected, and barring entry of the Soviet Union into the war, Japanese forces on the continent would be able to sustain themselves for some time. This continental base however would be of little use to the forces defending the Home Islands. Analysts predicted that the blockade of the Tsushima Strait and Sea of Japan would be between seventy-five and ninety percent effective, while the blockade of the north Chinese coast would be almost complete. Communications within the Home Islands would be increasingly difficult with the establishment of Allied air power on the Kanto Plain. Japan’s infrastructure had not been adequate, even in peacetime and the railways were especially vulnerable to air attack. Also, with Allied air power established on both Kyushu and Honshu, the Japanese could not depend on small coastal vessels getting through as they had done in the past. Food supplies would become critical in the large urban areas, while northern Honshu and Hokkaido normally produced a surplus of food, the difficult communications would stop much of that from being moved to the deficit in central and southern Honshu and northern Kyushu. Again, on the continent, food would be in a surplus to Japanese needs but transporting across to the Home Islands would be very difficult.

After Iwo Jima and Okinawa, many believed that diehard elements in the Japanese military would attempt to exert control over the Government and Japanese people in order to lead them in a suicidal defence of the Home Islands. The military analysts however doubted this scenario. While they recognised that some in the Japanese military would prefer to go down fighting, they felt that the Japanese people would eventually see how inevitable defeat was going to be and react with ‘depression and resignation to fate’. Even if the military took direct control of the Government, it would be likely that the machinery of Government would start to break down, crippling their ability to control the population. Should they remove the Government to the mainland, it would be likely that the Japanese people would feel deserted and accept an alternate Government set up by dissident factions or even the Allied Military Authorities. On the continent, they could only expect to control those areas garrisoned by Japanese troops. Overall, the Joint Chiefs never set down a firm plan for post-Coronet operations as they hoped that the Japanese would surrender after Operation Olympic had begun and that Coronet itself would be unnecessary. They hoped that clarification of what unconditional surrender meant might convince the Japanese to end the war before they suffered complete destruction and certainly worked for an amelioration of the terms laid out in the Allies’ demands. They placed no great faith in the atomic bomb and planning for the defeat of Japan proceeded without any great consideration as the atomic bomb’s power. In fact, the effects of an atomic blast, even its feasibility, were unknown before the Trinity test in New Mexico on 16 July 1945. Ten days after the test, the Joint War Plans Committee circulated a preliminary paper (‘Operations in Japan Following CORONET’, JWPC 333/1, 26 July 1945, Records of the Joint Chiefs of Staff (microfilm edition)) discussing possible post-Coronet operations. The plan emphasised the intensification of the air and naval blockade from the new bases on the Kanto Plain as well as additional amphibious assaults on strategic areas of the Home Islands. These new landings, along with additional operations from both the Olympic and Coronet lodgements would seal the Japanese defeat. The planners looked at five different areas that could be targets for additional land and amphibious assaults following Coronet. These were the Shimonoseki Straits in northern Kyushu, the Osaka-Kobe-Kyoto industrial area on the inland sea, Nagoya, the Hakodate-Aomori area on the Tsugaru Straits (separating northern Honshu from Hokkaido) and the Sapporo Plain on Hokkaido. The forces required for these operations varied from the landings on Hokkaido requiring around five divisions, while those in northern Kyushu requiring approximately nine divisions with the remainder required about eight divisions each. The planners set a target date of 1 July 1946 for these first of these operations, but there were still too many unknown factors at this point for them to recommend which one would have been undertaken first. As an alternative, they listed a number of contingencies that would affect the selection of the target. These included the level of Japanese defences at each target. If the Japanese retained large forces in northern Kyushu after both Olympic and Coronet then the strike would probably be on lightly defended Hokkaido. If the Japanese stripped the defences in the Nagoya-Osaka area to reinforce other areas than the strike might happen there, or if the Soviet Union entered the war and needed large amounts of American supplies then the target would be either the Shimonoseki Straits or Hokkaido to open a supply route to Siberia. Basically, the planners found it too early to tell where the axe might fall in post-Coronet operations.

The Shimonoseki Straits and northern Kyushu formed one of the most important strategic areas in Japan. A large industrial complex spread north from Fukuoka to Moji on the southern shores of the straits. A tunnel under the straits provided communications between Kyushu and Honshu. The straits connected the Sea of Japan and the Tsushima Straits with the Inland Sea. In the outline plan for northern Kyushu, the main assault would come from the Fukuoka area. After gaining a beachhead, Allied forces would advance northward to occupy the industrial complex of Yawata, Kokura and Moji, probably gaining control of the straits at the same time. In 1945, Osaka was Japan’s second largest city and Nagoya the third. Both were industrial centres and important ports and after Kyushu and the Kanto Plain, probably the most strategically important area in Japan and likely to be heavily defended. Other than northern Kyushu, the most difficult assaults would be these two cities. Osaka lies at the head of the narrow Kii Channel, the eastern entrance to the Inland Sea. Nagoya lies at the head of Ise Bay, with a geography not too dissimilar to that of Tokyo Bay. After examining the narrow channel and terrain in the area, the planners rejected the idea of a direct assault on Asaka and recommended instead to attack Nagoya and advance over land to take the Osaka-Kobe-Kyoto industrial complex. The terrain problems around Nagoya were broadly similar to those presented by the Kanto Plain and the solution suggested by the planners was similar to Coronet. The entrance to Isa Bay was as narrow as that to Tokyo bay. The outline called for an initial wave of four divisions to seize the three peninsulas forming the entrance to the bay. After securing the entrance, two additional divisions would advance up the western side of the bay in a series of amphibious bounds, a third division would sweep the eastern shoreline and a fourth division would land on D-Day+5 at the end of the Chita Peninsula, moving north towards Nagoya. After taking the city, these forces would receive reinforcements for the drive on the Osaka-Kobe-Kyoto area. Only a narrow mountain pass separated Nagoya from Kyoto in the lowlands near Biwa Ko and so forces could move through that instead of making a direct amphibious assault against Osaka. An amphibious assault on Hokkaido would face only light opposition, with analysts predicting only one regular division on the island and another defending northern Honshu. Amphibious landings in the Hakodate-Aomori area would enable the US to control a major naval anchorage at Matsu Wan, an airfield complex, the port of Hakodate and passage through the Tsugaru Straits to the Sea of Japan. To secure these sites however would require a complex operation with fourteen separate landings. A far simpler plan was to occupy the Sapporo Plain on Hokkaido, a large, level area that could provide plenty of airfields from which Allied airpower could control the Tsugaru Straits to the south and the La Perouse Straits to the north. In addition, the assault would only require some five divisions landing on open, lightly defended beaches near to their objectives.


Alternate History What if Operation Downfall happened?


Operation Downfall was the proposed Allied plan to invade Japan in 1945. As the European theater of World War II had ended, all the Axis Powers had lost, except Japan. They were the lone holdout that continued to fight. They themselves knew the war was lost, but were holding for a conditional surrender. This would've included conditions like the Hirohito being allowed to continue his rule and keeping at least some of their acquired lands, which was unacceptable for the Allies. At the time, the Manhattan Project was top secret, and the US generals themselves knew nothing of it. Thus, they drafted Operation Downfall as the final act to defeat Japan. In an alternate timeline, say the Manhattan Project was behind schedule, Operation Downfall would be put into play. What happens?

  • The US military, which included over five million projected troops, would do a full-scale naval invasion of Japan starting with the southern point of Kyushu. They would be supported by the British, Canadian, Australian and New Zealand militaries, which themselves would've made for at least six million troopers (likely more), 42 aircraft carriers, 24 battleships, 400 destroyers, and tens of thousands of fighter and bomber planes in the invasion.
  • Downfall would've had two parts: Operation Olympic and Operation Coronet. Olympic was tentatively to begin on November 1945, which would launch from Okinawa to the southern point of Kyushu. Afterwards, they would occupy the area as the new base of operations for the next part. Coronet would've been the invasion into Honshu, the main Japanese island, and into Tokyo itself. The attack on Tokyo would've been carried out by well over two million soldiers.
  • The US had a planned estimate of 54 Army divisions to take part: 14 in Olympic and 40 in Coronet. For reference, D-Day itself only had 12 divisions in total.
  • Japan itself had a plan of defense called Operation Ketsugo. The entire population of Japan, down to the last man, woman and child, would take part in a guerilla war against the invading Allied forces using their waning resources on guns, as well as knives, spears, bombs, improvised weapons, traps, and acquired enemy weapons. Japan's geography itself, 73% mountains, means they could've focused their entire defense on small chokepoints and form a wall of death.
  • While not part of the plan itself, the Soviets were also going to invade from north in Hokkaido after taking over Manchuria, and even had naval boats lent to them by the US.
  • If Downfall had taken place, it would've been far and away the largest amphibious operation in all of history.

Doggydog

Professional Attack Chihuahua

Onimech

Snazzy Custom Title Here

We have two situations of a pacific nation divided between southern capitalist state and a northern communist state. With the Soviets probably taking Tokyo long before the Americans make it too far into the main island.

Other than that the Japanese population dwindles down to a very tiny minority since this involves taking cities and countryside by eradicating nearly every living thing within it and moving on to the next and repeat. And element of sympathy for a Japanese person within almost any nation erodes down to almost nothing.

Reflection

Abloobloo

Reflection

More of a Zor than You

Said it before, will say it again. Operation Downfall is just fucking depressing to contemplate.

Sciman

We've had this one a few times now.

Essentially, the most plausible Japanese defense plan I've seen would start with a defense of the beaches similar to early war battles. This would include a use it or lose it mentality, with Japan throwing every major piece of equipment that could get into action at the invasion force. The entire air force, navy, and submarine force capable of engaging would engage, with about 80% of the air force converted to kamikaze missions, plus massed suicide boats. Most major naval vessels would simply be beached or left in shallow water to act as gun batteries. It's possible that nuclear attacks would have been used to soften the landing areas, which would then have troops marched through, expect US soldiers dying of radiation poisoning.

When allied forces got past that, which they would, they'd meet the Japanese mobile reserves and fight some more. This would include a portion of the tank forces, but would be otherwise less well equipped than the main defense force on the beach.

After this, you would get an insurgency, which would include a large portion of the civilian defense forces and several of the greener units that had just finished training, with at least two specifically trained in guerilla warfare, as well as the army intelligence units specializing in unconventional combat. Essentially, America gets a taste of Vietnam early and a bit of what Japan's been dealing with in China. Mostly the civilian elements would run messages, provide supplies, and locate allied forces, rather than engage in combat, but if there was a target of opportunity they might very well try and get a knife into someone. It's not that every civilian is out to kill you, but any civilian could be. This likely leads to some atrocities and that in turn leads to more resistance and guerilla warfare. If the Soviets have part of Honshu as part of their occupation zone, this phase can last for decades as the USSR supplies guerillas to bleed the Americans. On the other hand, Japan was more concerned about the Soviets than the other allies, so might not accept the help or might even surrender just to keep/get the Soviets out.

Eventually, allied forces would gain control of the major cities and either rule directly or install a puppet government. These would not be seen as legitimate, meaning their authority won't be respected, unless the allies have their guns pointed at every village to enforce it. Chances are that Hirohito is executed, losing the primary chance of the American installed government ever being seen as a legitimate authority. Meanwhile, the trickle of dead "after the war is over" is not going to be great for morale at home, but America wants Japanese bases for the Cold War, especially after China goes communist. On the other hand, it could be somewhat harder to intervene in Vietnam or Korea, with Japan not completely friendly, even if the bases are there.

Most likely the Ryukyus are either an American territory or end up as the Ryukyu Republic. Japan herself will emerge as either a territory, a puppet state, or a state hostile to the US. It is unlikely that Japan sweeps questionable allied actions under the rug in this time line, rather she probably makes them a focus of education much as you see with Korea and China in regards to Japanese war crimes. The population is very likely to be hostile to Americans, as well as Australians and British, possibly Russians as well. On the other hand, Japan also won't be wealthy in this time line, and will have suffered anywhere from a quarter to three quarters population loss*, so even if she's entirely revanchist towards the US it likely doesn't matter much.

* Downfall itself would kill five to ten million, with more dying to starvation and atrocities committed as reprisals for the guerilla campaign. This out of a population of only 75 million.


Operation Downfall 4: Allied plans for Olympic and Coronet - History

Posted on 08/06/2010 7:42:11 AM PDT by tlb

OPERATION DOWNFALL, to be complete within one year of the end of the war in Europe, had two major components.

* Olympic . November 1, 1945. Invasion of Southern Kyushu to provide a large base for naval and air forces within range of Tokyo.

* Coronet . March 1, 1946. Invasion of Central Honshu and Tokyo.

Olympic entailed landing three corps on southern Kyushu, the most southern of the four Japanese home islands. The center portion of Kyushu is almost impassible mountains which would be difficult to transit and was to be used to isolate southern Kyushu from counterattack by Japanese troops from northern Kyushu (Nagasaki). The landings were to be by troops already in the Pacific covered by 34 carriers and by land based aircraft from Okinawa. B-29's would interdict reinforcements. Southern Kyushu had a large bay, harbors, and many airfields. The intent was to base naval support craft and to establish 40 air groups, many redeployed from Europe.

From southern Kyushu, fighter air cover could open the Inland Sea to the US Navy and interdict transportation as far as north as Osaka fighter bombers could close shipping from Korea and China medium bombers and could destroy transportation, material, and installations around Tokyo and support the invasion troops large bombers (B-17 and B-24) could range over all of Japan. Meanwhile, B-29's from the Marianas could continue to wipe out industrial centers.

There were two naval groups.

The Strike Force, 3rd Fleet, had 21 carriers and 10 fast battleships to range up and down the length of Japan to suppress Japanese forces with priority to destroy aircraft and transportation.

The Assault Force, 5th Fleet, had 26 carriers, plus 8 detached from Strike force for the invasion period, 13 slow battleships, 20 cruisers, 139 DD, 167 DE, and support ships for a total of 800 warships. Troops and their equipment were to come from the Philippines and Marianas in 1,500 transports. All combat troops were from the Pacific theater none redeployed from Europe.

The plan called for a diversionary display by the floating reserve on Shikoku, the smallest of Japan's four islands, before their landing on Kyushu. Support troops including engineers to build airfields were to land starting on Y-Day + 2 some of these were to come from Europe.

At the time of the start to planning of Olympic, there were 1-1/2 divisions based on southern Kyushu these with various service bases there amounted to about 45,000 men. Planners expected an additional three divisions to be moved into the area by the time of the landings.

The Japanese were able to predict the landing using the same logic as US planners and moved 9 more divisions into the area for 216,000 men by the time of the surrender in august. More men, material and defenses would have been assembled by the November date for the invasion.

Each side of the central bay had an army, each was divided into two functions - a static defense force on the beaches to fight to the death while allowing reinforcements to arrive, and the mobile reserve to push the American back into the sea. The three logical landing beaches were defended from the shore to the nearby mountains with new troops. The reserves located in the mountains were experienced troops from Manchuria with light tanks. Supporting the troops were the remnants of the navy and air force, lightly armed volunteers, and an array of "special" weapons.

The air forces contained 5,600 conventional combat planes and a similar number of older planes and trainers suitable as Kamikazes. The combat planes were withdrawn from Kyushu and the Kamikazes moved in. Japan was so short of aircraft and fuel that B-29's and carrier task forces were not routinely attacked so as to conserve combat aircraft for the final battle. Equal numbers were assigned to Kyushu and Tokyo areas. As the date for the first battle approached, more were moved to Kyushu with the Tokyo forces to be replaced with promised new production.

Kamikaze tactics were initiated in the Philippines and became a doctrine that inflicted terrible damage to US warships off Okinawa. The invasion of Kyushu would see the distance reduced, flying over familiar land instead of over-water navigation, and with targeting changed from warships to troopships the plan was to inflict intolerable damage to the invasion force before it hit the beach.

The following "special weapons" were established on southern Kyushu.

* Kamikazes -- 2,100 army planes and 2,700 navy planes. * Baku - suicide missile carried by a bomber. * Mini-subs, each with 2 torpedoes, 500 were building. * Fleet submarines -- rearm the 57 remaining that had been dedicated to resupply of outposts. * Kaiten - suicide torpedoes with a 20 mile range. * Shinyo - suicide motorboats. The army had 1-man, 17 foot motorboats. The navy had 2-man, 22 foot boats. * The largest surviving warships were destroyers that were prepared for suicidal attack on the invasion convoys. * On the land, human mines in which soldiers had explosives strapped to their bodies and were to crawl under a tank. Other explosives were packed with a suction cup to be attached to the side of a tank. And shaped charges on a long pole were to be detonated on the side of a tank. * Japanese paratroopers were to attack Okinawa to disrupt flight operations during the invasion period.

Rather than invade Japan, the country could have been blockaded with a ring around the Yellow Sea from Shanghai to Korea. This was not assured to cause the surrender of Japan. The direction of the war would have been towards reinforcing China and supplying the Soviet Union for their movement of troops into Manchuria, Korea, and mainland China.

A plan resurrected after the enemy buildup on Kyushu exceeded all expectations, was the occupation of the less well defended northern island of Hokkaido and northern part of Honshu. This would have been of equal distance from Tokyo, but further from American army, naval, and air force centers. Shipping was already a problem with large numbers unreleased from the Atlantic needed to supply Europe and return troops to the US to redeploy air and service forces from Europe to the Pacific, to supply the Pacific buildup and to move several corps to the invasion sites. Every tanker in the US fleet was required to provide the millions of gallons of fuel required by the ships involved in the Kyushu operation. More fuel and shipping would be required to move 1,100 miles further away to the north. That plan was dropped.

There are two sets of potential casualty figures a low number used to gain approval to proceed with the operation and a high number used to plan reserve forces, medical needs and, as it turned out, to claim as lives saved by use of the atom bomb. These figures changed over time, starting low and going higher as the enemy build-up on Kyushu was discovered.

The low casualty figures were based on the landings at Okinawa, Lingayen Gulf, and Normandy. Okinawa and Lingayen Gulf were undefended on the beaches, the fighting took place in the mountains where each Japanese caused one US wounded of which 20% resulted in US deaths. Normandy had the same three-beach landing pattern, but two beaches were relatively easy, only the landing at "bloody" Omaha was vigorously defended.

All three Kyushu beaches were defended in depth. A shoreline defense such as Omaha beach and a mountain cave defense as on Okinawa all to the death. It would have been more realistic to triple the rate of Omaha beach rather than take the average of the three Normandy beaches as the planners did. There was also a difference in scale. Normandy landed 5 divisions plus 3 airborne divisions. Olympic was to land 14 divisions. Coronet was to have 23 divisions.

The defended beach at Tarawa was a shock to Marine landing with unexpected losses. The US invasion tactic was then changed from surprise to heavy bombardment. The Japanese had to change their defensive positions in the later Pacific actions from defense of the beach to the mountains. Kyushu was to have both forms of defense: well prepared installations near the beaches and well prepared caves in the mountains, with mobile tank forces.

The US planners expected that radar would detect Kamikazes coming through the mountains, carrier fighters would be vectored to intercept them, and proximity-fused ship's anti-aircraft fire would take out any that got through. However, 250 highly maneuverable warships were hit a few months earlier at Okinawa with these same defenses, in open water the prospects of loaded troop ships taking casualties was high and each hit could take half-a-thousand lives. Whereas two Messerschmitts were able to attack troops on the Normandy beaches, 5,000 Kamikaze were aimed at the approaching troop ships while still at sea. It would be reasonable to increase the hit rate of Kamikazes from nearby bases, yet the planners reduced it.

Japanese planners expected almost 500 ships would be sunk during the landing. US planners expected 15-20% losses, they had no experience with mass air attacks on merchant ships at sea.

Good weather was required for close air support on the cloudy islands of Japan. A typhoon had once saved Kyushu from invasion by Mongols in 1281. A storm that forced the carriers to withdraw or even to cause the 2,000 planes to remain on deck, would take away an important part of the invasion support. A storm would also hamper getting supplies over the beaches to the armies.

The original plan was for 9 divisions to attack 3 divisions of defenders. As enemy reinforcements were observed, the size of the invasion force was increased. The final plan had 18 U.S. divisions attacking 11 IJA divisions in defensive positions. Most sources give the advantage to defenders by 3:1, that is, attackers must outnumber defenders by three to be sure of victory.

Casualty figures were a guess that changed with time. There are sufficient numbers available to support any post-war position that any author chooses to take. Low numbers are quoted as reasons to do the invasion, 125,000 for Olympic and to end the war. High numbers, one million US casualties for Downfall, are quoted to justify the A-bomb and end the war. Typically, 25% of casualties are deaths. On average, 5 Japanese soldiers died for each American death.

Japanese casualties were not subjected to planning. If all troops resisted to the death, then the typical survival rate would have only included injured and unconscious soldiers. 216,627 troops were surrendered on Kyushu alone -- more than were expected -- and this was two months before the planned invasion so the number of defenders would have increased. Civilian casualties are a real unknown. 97,000 were killed in the bombing of Tokyo on March 9 the numbers from land warfare would also be high. Consider ratios of any proportion you desire. Civilian losses in some European cities were considerable certainly Japanese casualties would be in the multiple millions.

Coronet was the attack across the Kanto plain to capture Tokyo. The broad plan was still going through refinement.

Naval bombardment by guns and air would begin at Y-15. There would be two simultaneous assaults on Y day.

First Army was to land on the southern half of Kujukuri Beach with 4 divisions to secure a beachhead. On Y+5, with two more divisions landed, they would move across the peninsula to clear the east side of Tokyo Bay and move north to take the port city of Choshi. Service troops would built land-based air bases under the cover of carrier aircraft. Thirty air groups were expected to be in place by Y+30.

Almost simultaneously, Eighth Army would land at Sagami Bay with four divisions to establish a beachhead, secure the Miura Peninsula and Yokosuka naval base. At Y+10, two armored divisions would land and move straight north, beind the industrial cities on Toyko Bay, to establish a blocking position north of Tokyo. Other elements were tasked to take the port cities of Yokohama and Kawasaki to provide supply points for the troops.

First Army was to attack across the Kanto plain to Tokyo about Y+30 with Eighth Army tanks ready to provide assistance. Tokyo had already been extensively destroyed by bombing.

Coronet was a larger operation than Olympic, but the landing on Kyushu, the southern island, was expected to be the more expensive because all of the homeland defensives would have been expended there and the promised replacements to ward off Coronet would have been made industrially impossible. Several thousand Air Force fighters and medium bombers would be flying from a hundred airfields on Kyushu. A 100 carriers could have been available including new construction and those coming from the Atlantic.

The Joint Chiefs expected the Japanese to surrender after exhausting themselves in Operation Olympic. Thus Coronet would not be required.

However, if necessary, follow up operations after Tokyo would have been initiated in the south, central, and north of Japan with US troops from Europe who had taken leave in the US -- only Air Force, air field construction, and service units had gone from Europe directly to the Pacific. And troops from Allied countries would be available.

* South. The northern, more industrialized half of Kyushu would have been taken. * Central. The next largest industrial cities would have been taken with landings to take the peninsulas of Ise Bay, take Nagoya and then march overland to Osaka, Kyoto and Kobe. * North. A landing at Sapporo on Hokkaido followed by taking the anchorage at Mautsu.

Hindsight . Capture of the Marianas as B-29 bases turned out to be the key to the end-game. The campaign in the Philippines and Peleliu were not necessary except to force the final battle with the Japanese fleet and as a place to absorb Japanese army troops and air forces for destruction. Also, an alternative considered at the time, the invasion of Formosa to open access to China and as an alternate base for B-29's would have been equally unnecessary. These resources could have been applied sooner to capture and build air bases at Saipan, Iwo Jima and Okinawa, which were instrumental in the rapid end of the war. But the secret weapon was a secret and it might not have worked or been ready in time.

Olympic - Southern Kyushu Troops . All were US from Pacific area Autumn of 1945 6th Army.

Sep 1 . Honshu, Kyushu, Strategic Air Force (B-29 Okinawa) continue strategic targets. Sep 1 . Shimonoseki Straight / ports, Strategic Air Force continue isolation mining. Sep 18. Hong Kong , British strikes. Sep 28. Canton , British strikes. Oct 1 . Ningpo , Chusan, China , Strategic Air Force isolation bombing. Oct 18. Honshu, Inland Sea , 3rd Fleet : TF-38 (US) , TF-37 (UK) strategic support Oct 21. Kyushu , Strategic Air Force N-S isolation and anti-buildup Oct 24. Kyushu , 5th Fleet preliminary bombardment, mine clearing, interdict highways. Oct 27. Outer Islands , 40th Inf Div Oct 28. Tanega Shima , 158th Reg Combat Team Oct 30. Shikoku , feint by 9th Corp : 77th , 81st , 98th Infantry Divisions Nov 1 . West , 5th Amphibious Corp : 2nd , 3rd , 5th Marine Divisions Nov 1 . South , 11th Corp : 1st Cav , 43rd Inf , Americal Divisions. Nov 1 . East , 1st Corp : 25th , 33rd , 41st Infantry divisions Nov 22. Where needed : 11th Airborn Division. Nov 23. As needed or SW : 9th Corp : 77th , 81st , 98th Infantry Divisions Dec - . Build air fields : support troops and air crews from European theator. Jan - . Attack all military and industrial areas of Japan by air and sea.

Planning Alternatives for Coronet -- Spring of 1946 Coronet was the attack across the Kanto plain to capture Tokyo. The broad plan was still going through refinement and only outline drafts had been completed by August 1.. The initial plan called for three landings using 25 divisions:

* a blocking force landing at Mito on the coast north of Toyko and move west to establish a position north of Tokyo. * the main force landing in Kashima Beach south of Choshi with a goal to clear Chiba province including the east side of Tokyo Bay and build airfields and land tank divisions before moving across the Kanto plain to attack Tokyo from the east. * a southern landing at Sagami Bay 30 days later would take Yokosuka naval base and move rapidly north to be west of Tokyo. * the three armies would then move on Tokyo.

A second plan, subject to further change, dispensed with the northern force and was reduced by 2 divisions. This acknowledged that redeployment from Europe was not going well -- two million experienced veterens were being released and units were in disarray.

* a landing was to be made on Kashima Beach east of Tokyo with 5 divisions to clear Chiba province, cross the Boso peninsula to Tokyo Bay, built land-based air bases under the cover of carrier aircraft, and built up 9 infantry and 2 tank divisions including some redeployed from the European theater. * The major landing was to be made ten days later at Sagami Bay, the outer part of Tokyo Bay, southwest of Tokyo with the goal to take the naval base at Yokosuka and open Toyko Bay and build up to 8 infantry and 3 tank divisions. * Then both armies were to move on Tokyo at D+30.

o The southern, Sagami force, was to move quickly north behind the cities on Tokyo Bay with elements tasked for the ports of Yokohama and Kawasaki, while the main force continued north to be northwest of Tokyo. o Meanwhile the Navy would move into Tokyo Bay to provide support from the south. o One corp is unaccounted for in the surviving drafts of the plan at the time of the surrender, which shows that the planning was still in progress.

A third plan retained the three landings of 25 divisions with 1 paratroop division in reserve. This was MacArthur's plan and assumed that more troops were available than the Joint Chiefs thought possible.


Operation Downfall – The Invasion Of Japan

Now DECLASSIFIED, only a few Americans back in 1945 ever were privileged to have access to a plan which, to this day, few Americans – and fewer Australians – still know about.

Buried deep for decades in the US National Archives in Washington, thousands of yellowing, dusty pages marked TOP SECRET now reveal the enormity of OPERATION DOWNFALL – the proposed invasion of Japan.

Atomic bombs dropped on Hiroshima and Nagasaki brought the Japanese to heel – and to unconditional surrender.

After that all interest in a plan for invading the Japanese homeland became obsolete.

The incredible story of the grandiose planning for American forces to invade Japan has been summarised by James Martin Davis following a study of the so-secret material once it was DECLASSIFIED from top secrecy.

Two massive military undertakings were planned. They were to be carried out in succession – OPERATION OLYMPIC on Nov 1 1945 and OPERATION CORONET on March 1 1946.

In the first invasion, combat troops would be landed by amphibious assault after an unprecedented naval and aerial bombardment. Fourteen combat divisions of American soldiers and marines would land on heavily fortified and defended Kyushu, southernmost of the Japanese home islands.

The second invasion, in the following March, would send 22 more American combat divisions against one million Japanese defenders to assault the main island of Honshu and the Tokyo Plain in a final effort to obtain unconditional surrender.

With the exception of a part of the British Pacific Fleet, it would be a strictly American operation – (though it is reasonable to assume that ships of the RAN operating for so long with Task Forces of the US 7th Fleet most probably would have participated).

In his summation, James Martin Davis states the overall plan called for use of the entire United States Marine Corps, the US Navy in the Pacific and for use of the US 7th Air Force, 8th Air Force recently deployed from Europe, the 20th US Air Force and for the American Far East Air Force.

More than 1.5 million combat soldiers, with millions in supply would be directly involved in the two amphibious operations.

A total of 4.5 million American servicemen – more than 40% of all still in uniform in 1945 – would be involved.

One US Admiral estimated there would be some 250,000 Americans killed or wounded on Kyushu alone. A General estimated American casualties from the entire operation would be one million men by the fall of 1946.

As the invasion grew imminent, the massive power of the United States Navy would approach Japan – two awesome fleets, the Third and the Fifth.

For several days battleships, heavy cruisers and destroyers of those fleets would pour thousands of tons of high explosives into targets as a prelude to the launching of the land invasion forces.

During the early hours of Nov 1 1945, thousands of American soldiers and marines would pour ashore all along the eastern, south eastern, southern and western coasts of Kyushu.

The Eastern Assault Force, made up of the 25th, 33rd and 41st Infantry Divisions would land near Miyaski at beaches called Austin, Buick, Cadillac, Chevrolet, Chrysler and Cord moving inland to capture the city and its airfield.

The Southern Force, consisting of the 1st Cavalry Division, 43rd Division and others would attack beaches named Dusenberg, Essex, Franklin and others, to try and capture Shibushi, then the city of Kanoya and its airfield.

On the Western Shore of Kyushu at beaches named Pontiac, Reo, Rolls Royce, Saxon, Star, Studebaker, Stutz, Winton and Zephyr, the 5th Amphibious Corps would land Marine Divisions 2, 3 and 5 sending half of its force to Sendai and the other half to Kagoshima.

On Nov 4 the reserve force consisting of the 81st and 98th Infantry Divisions and the 11th Airborne Division would be landed near Kaimondake at the southern tip of Kagoshima Bay using beaches designated as Locomobile, Lincoln, La Salle, Hupmobile, Moon, Mercedes, Maxwell, Overland, Oldsmobile, Packard and Plymouth.

If all went well with that initial OPERATION OLYMPIC, then OPERATION CORONET would be launched on March 1, 1946 – again involving massive US combat forces twice the size of the initial operation and using as many as 28 Divisions on Honshu, the main Japanese island.


Jets in Operation Downfall?

I'd like to get some feedback on a question that's been in my mind recently.

Operation Downfall - the invasion of Kyushu (Olympic) in November 1945 and Honshu (Coronet) during the spring of 1946 - was cancelled because of Japan's surrender, but every discussion I've ever seen predicted grim casualty estimates had the invasions taken place.

One of the big threats was kamikaze aircraft. They did a real number on allied naval vessels.

Throughout the war in the Pacific, all deployed US aircraft were propeller-driven. But by 1945, the US had an operational jet fighter - the P-80 Shooting Star. A few were deployed to Italy before VE day, but they never saw combat. The RAF had deployed a jet fighter - the Gloster Meteor - even earlier, using it to intercept V-1s over Britain. By mid-1945, both the US and UK would have learned much from captured Me-262s and improved existing allied jets, though I don't know how far along such improvements would have been by the time Olympic was scheduled.

Carrier-borne jets wouldn't have been available by November 1945, but Meteors and Shooting Stars could presumably have operated out of Okinawa.

Does anyone know if plans for Downfall discussed the possibility of jet interceptors to bring down kamikazes? And would this have had any impact?

Chlodio

A quick check on the combat radius of the P-80 and the Meteor shows that even operating from land bases in Kyushu they could not have reached the Tokyo Bay area. They could have flown fighter sweeps over southern/ western Honshu, but the Japanese could probably redeploy their aircraft to northern Honshu out of range of the Allied air bases on Okinawa and Kyushu. Once the Allies got far enough inland at Tokyo Bay they could have built air bases there. It's anyone's guess if these airbases would have been operational before Japan surrendered.

I doubt any of the carriers could have been modified for jet operations by March 1946.

I don't see much potential for any land-based planes to fly cover over the fleet near Tokyo Bay except possibly the P-51 which had the range. It would have been a stretch for the P-47. By the spring of 1946 the US would have had even more aircraft carriers in commission than they did in 1945. It's anyone's guess how many carriers would survive operational after Olympic and whether these carriers could be repaired in time for Coronet. Combat Air Patrols over the fleet would almost have to be by carrier-based planes. Where land based planes could effect Kamikaze operations was by bombing the airbases before the Kamikazes took off from them. P-80s and Meteors could escort the bombers, at least over southern and western Japan.

I'm unaware of specific plans to deploy P-80 and Meteor squadrons to the Pacific, but it seems reasonable that some would.


WI: Operation Downfall happens?

In general I agree with the points made by LeX with the exception of two. If Stalin believed the geostrategic/geopolitical advantage was great enough, then ruffled feathers did not matter. This is exemplified by the 1939 Non-Aggression Pact with Germany where the territorial gains in Poland and the Baltics were sufficient to warrant becoming an international pariah. Again, Soviet demands for Polish territory nearly sank the Tehran Conference in 1943. Soviet control of Eastern Europe was enough to precipitate a 40-year Cold War. Stalin was cautious and calculating, but not above ruffling feathers.

Secondly, the nonviability of Manchuria is precisely the reason why the Soviets could establish a satellite state. Power will not exist in a vacuum. Stalin was not above breaking treaties, his denunciation of the Non-Aggression Pact with Japan without the one-year notice required has been discussed in detail in the above threads. Manchuria (and Inner Mongolia) was returned to Nationalist China under the terms of the 14 August 1945 Treaty of Soviet-Chinese Friendship, but had not effectively been under central government control since the 1894-5 Sino-Japanese War. Fifty years had loosened emotional links to China, even if no love existed for the Japanese or their puppet rulers to replace those links.

One of the provisions of the Treaty of Soviet-Chinese Friendship was that the Chinese Eastern Railroad would be under joint Sino-Soviet control for an indeterminate amount of time. The Soviets knew that its border with Korea was too short to fulfill communication and logistical requirements. Air transport and sea lanes were considered inadequate and unreliable. An extensive land connection was needed to support the client state already planned for north of the 38th Parallel.

Within weeks of the signing of the Treaty of Soviet Chinese Friendship, Stalin broke it by unilaterally declaring a lease over the former Kwangtung Area around Port Arthur. The official reason was to erase the stigma of the Russian defeat in 1905. Communist mayors and officials were installed beginning on 25 November 1945. I believe this historical template would be followed in the event Operation Downfall was proceeded with. Stalin also broke the Treaty by dismantling industrial infrastructure and withdrawing troops before Nationalist units could replace them. This gap allowed the People’s Liberation Army to move into areas the Japanese had previously effectively denied them.

Events have a momentum of their own. As the Soviets move deeper into Manchuria, local civil-military governments will be established to support and sustain further military advances. Initially, most officials are Soviets, since CCP cadres were concentrated further south. As the Soviets advance into areas the CCP was active, they will be chosen for official posts, but circumstances will likely ensure they are more loyal to Moscow than Mao. The establishment of an administrative state to support the Manchurian Strategic Offensive Operation will eventually extend to the entire former state of Manchukuo (which included much of Inner Mongolia) by military necessity. It will also be easy to assert that the “people” of Manchukuo “invited” the Soviets to invade and were now “inviting” them to stay. Once the effort is expended to create a state, I’m not sure Stalin simply hands it over to the Chinese, whether they be Communist or Nationalist.

In my view, these events would strongly support the observation by LeX that China might end up split between north and south. The CCP is deprived of the windfall of Japanese weapons captured by the Soviets. Once Soviet intentions to keep Manchukuo were obvious, Mao faces the options of either accepting it in the name of Communist solidarity and being branded as traitors or waging simultaneous guerilla warfare against the Nationalists and the Soviets. Either way, the survival of the Nationalists would be enhanced.

Frankly, even if the Japanese air forces fail to sink a single invasion transport, trying to conduct an amphibious landing while outnumbered against an opponent with more accurate intelligence than you and your air and naval power are all tied up is a recipe for disaster. The Dieppe raid was exactly such a disaster - except there the Allies actually outnumbered the local German troops seven to one.

Some of the loss of numerical superiority would be made up by the great strides the Allies had made in conducting large-scale amphibious operations, but that's not nearly enough.

I think we may be talking past each other on this point I was responding to this:


As you note here, I did not "switch" but rather presented both, in that more context was being given to the 6:1 ratio..

Right but they kind of contradicted each other and you claims that half or more of the invasion fleet will be blown out the water by kamakaze.

And there will be cases of hit that do nothing as well, also the post war survey was counting "damaging near misses" in with the hits as well for those 1 in 44 hit figures. and frankly that could be anything!

Yes, you asked where all the pilots for this were and cited the 6,200 trained pilots I was already aware of, in that there was the basis for doing the Kamikaze strikes. I did not mean that they would waste all of their trained pilots on that, but rather was I responding directly to your question.

Yes, not all of those pilots would be Kamikazes and that's why I cited all the other planes reserved for other missions. And sure, there's not enough planes for all of them, but there is enough planes for the Japanese objectives and planning structure for OLYMPIC. As Gianreco notes, Kyushu was getting the priority..

Right but you've been constantly talking about 6000 kamikaze attacks, you do so below as well. You get that you can't say the above and then claim 6000 kamikaze attacks as well. I'm happy with your figure of 6200 pilots, but the point is they wont be all kamikaze and you've consistently assumed they will be.

6:1 was, as noted, the hit ratio, not the sinking ratio, which was the mistake I made in mis-remembering. 44:1, as another user pointed out, was the actual ratio to sinkings.

I also need to point out, again, that there was not 2,550 Kamikaze attacks for Okinawa. That figure include 500 IJAAF planes that were on more conventional missions included in the total and over 800 aborts by actual Kamikazes the real figure is, as previously noted.

The aborts counts because attacks that abort/fail are still attacks in terms of resources devoted to making them at the time. (You can of course try again with those planes and pilots if they also get home alive, and if the infrastructure and resources exist for them to go again). For instance if the allies flew a 50 bomber raid and 10 planes had to veer off and abandon their bombing runs because of heavy flak it's still a 50 bomber raid right? It also make the point that actually no not every pilot designated a kamikaze when taking off actually ended up making a kamikaze attack when it came to it for all sorts of reasons.

I'm not even sure about the 500 IJAAF planes are being counted here the surveys figure says 2550. But TBF I can see why the discrepancy might have come up. Not all kamikaze attacks were planned but rather a spur of the moment thing decided due to the specific context the pilot was in. So not every plane that ended up attempting a kamikaze attack was initially sent out to do so but made attacks attacks anyway and that would be counted.

So again every single possible Kamikaze on the initial attack in the first landing with nothing held back, and all the available pilots! Plus that's not close to 20% of the naval assets in Olympic (unless you are assuming that they will only be attacking 977 LSD, LSM, LST, and LSV landing craft, which is somewhat hopeful to say the very least)

6,255 x 7 = 43,785 casualties

To put that into perspective, casualties for Iwo clocked in at 20,000.

Only no one is saying the invasion fo Kyushu wouldn't be bigger than Iwo Jima with more causalities (Okinawa is 2.5x Iwo Jima, and it going t worse teh Okinawa as well), I was contesting your initial claim that Kamikazes will destroy half or more of the landing fleet. And again see above that's every single possible kamikaze pilot, it just not realistic.

And Frankly US tactics were improving too. Plus there is still the questions I asked about this idea of the Japanese parking 6000 kamikaze pilots and planes all on Kyushu just in practical terms, not to mention air campaign that would be waged against them that they can't fight back against prior to the invasion etc, etc

I haven't seen the page, but I'll take the claim at face value. The book in question isn't an academic one, but a fictional one. Here is an academic one:

Its the same ratios I quoted earlier.

History Learner

No, because the 6:1 ratio is the amount of planes it takes to achieve a hit and, on average, seven casualties were incurred per plane hit. These don't contradict at all, and rather give context.

44:1 is specifically sinkings, not damages or anything else. Damaging near misses would be counted in the 6:1 ratio.

I honestly do not get what you're attempting to argue at all here. There was over 12,000 planes and 18,000 pilots, so no, and I've already provided the layout of Japanese planning which envisioned 9,000 total planes with 6,000 reserved specifically for Kamikaze attacks.

Aborts do not count in the 6:1 or 44:1 ratio, specifically because both ratios require the plane to hit the target. You're attempting to conflate successful missions with total sorties.

Then they do not count, as we are specifically talking about Kamikaze missions.

All but 300 were to target the invasion transports so yes, they will be focused in almost solely on them, and yes, IGHQ planning called for maximum sustained operations in the first 10 days so as to inflict as much damage as possible while they are still loaded. As for the specific targets, yes, actually, the 1,000 actual transports were the targets. To quote Gianreco:

I never made the assertion that anyone wasn't saying Kyushu would be bigger. As for the Kamikaze aspect, I'm completely willing to back away from that claim, as I already have previously.

Japanese tactics were also improving. To give an idea of one such example, again from Gianreco:

D.M. Gianreco has an online article here you can read, and it should be very chilling. During the closing phases of Okinawa, the Japanese decided to combat test their "new" weapon and with the deployment of three aircraft they achieved a hit on each attempt. More chilling, of the three strikes, one resulted in a sinking-the destroyer U.S.S Callaghan. With over 5,000 planes and a demonstrated success record, the ramifications of this should be obvious.

Then you confused the ETO ratio of 2.16 with that of the Pacific, which is 7.45 per 1,000 per day.

I don't see how a lack of Nationalist troops moving into Manchuria would have changed the Soviet calculus that much. Stalin had little strategic interest in China beyond its being a buffer or at least a weak, non-hostile state. Overtly taking over or puppeting parts of China, especially the region that arguably triggered the Second Sino-Japanese War when the Japanese took it in 1931, would not have benefited Moscow if its goal was to keep China vaguely friendly.

You mean if the Soviets advanced into China proper? IOTL the Red Army did occupy all of Manchuria, no need to move "deeper" into it.

The Soviets would probably exert more political influence over Mao's movement, but unless there was some pressing reason I think Stalin would have largely left the CCP to its own devices after securing the railway/port and stealing Japanese industrial objects.

History Learner

Oboro

Eric C Johnson

I don't see how a lack of Nationalist troops moving into Manchuria would have changed the Soviet calculus that much. Stalin had little strategic interest in China beyond its being a buffer or at least a weak, non-hostile state. Overtly taking over or puppeting parts of China, especially the region that arguably triggered the Second Sino-Japanese War when the Japanese took it in 1931, would not have benefited Moscow if its goal was to keep China vaguely friendly.


You mean if the Soviets advanced into China proper? IOTL the Red Army did occupy all of Manchuria, no need to move "deeper" into it.

The Soviets would probably exert more political influence over Mao's movement, but unless there was some pressing reason I think Stalin would have largely left the CCP to its own devices after securing the railway/port and stealing Japanese industrial objects.


This just isn't Stalin's style in the absence of a powerful threat like Nazi Germany vis-a-vis Poland, there is simply no need to cause diplomatic bad blood with the Nationalists and sabotage the CCP's efforts to conquer China by making them look like an obvious fifth column. Of course, this could happen by accident if the Soviets overstay their welcome, but the fact that they could let CCP cadres take over the Northeast the way they did IOTL, plus the pressure to demobilize would make this unlikely.

Based upon the historical record, I find no evidence Stalin was concerned with maintaining cordial relations with Nationalist China. Point by point.

“This just isn't Stalin's style in the absence of a powerful threat like Nazi Germany vis-a-vis Poland, there is simply no need to cause diplomatic bad blood with the Nationalists and sabotage the CCP's efforts to conquer China by making them look like an obvious fifth column.”

Regarding Stalin’s style in the absence of a powerful threat. The military operations against Lithuania, Latvia, Estonia and Finland in October-November 1939 were all made in the absence of a powerful threat, and as I noted, provoked a strong reaction in Great Britain, France and the United States.

On 29 June 1945, Stalin forced Czechoslovakia to cede the Carpatho-Ukraine to the USSR, although Czechoslovakia posed no powerful threat. In December of 1945, Stalin attempted to annex Iranian Azerbaijan, which resulted in strong diplomatic protests by the United States. Iran posed no powerful threat either. As I already noted, the Port Arthur Lease unilaterally proclaimed by Stalin certainly fit this pattern of either taking, or attempting to take territory from weaker nations. It is significant that Port Arthur was not returned to China until after the death of Stalin.

Bad blood already existed between the Soviets and Nationalists. It began with the slaughter of Chinese Communists in October 1926 in Shanghai. In November 1929, the Special Red Banner Far Eastern Army employed ten divisions to decisively defeat the Chinese Northeastern Army, forcing the Nationalists to sign a humiliating Khabarovsk Protocol on 13 December 1929 to obtain an armistice. In 1931 the USSR broke diplomatic relations, recalling its own diplomats and expelling the Nationalists. Between January and April 1934, 7,000 Soviet GPU troops invaded Sinkiang (Xinjiang) but were defeated by the Nationalist 36th Division. Between April and October 1937, the Soviets attacked again more successfully incorporating armor and air support to virtually destroy the Nationalist 36th Division.

The Nationalists accepted this defeat because of the commencement of the Sino-Japanese War in July 1937. The Soviets viewed the Japanese as a greater threat and on the grounds of “the enemy of my enemy…” restored diplomatic relations and provided about U.S. $250 million dollars in military aid by April 1941. Upon the signing of the Soviet-Japanese Non-Aggression Pact that month the Soviets cut off all aid, which the Nationalists regarded as a tremendous betrayal.

On 26 November 1940, the Nationalist commander in Sinkiang, Sheng Shicai was forced by the Soviets to sign the Agreement of Concessions which virtually made Sinkiang a Soviet satellite. In November 1944, the Soviets set up the Second East Turkestan Republic which declared its independence from China. The USSR signed the 15 August 1945 Treaty of Friendship to fulfil a promise made at the Yalta Conference, and afforded it the same respect as other Yalta promises such as free elections in Poland. The Soviets recognized Chinese sovereignty over Sinkiang, but did not disarm their satellite Uighur troops, withdraw the Red Army officers advising them, or disband the Second East Turkestan Republic.

The Nationalists responded with a military assault, which was attacked by Soviet aircraft in October 1945. Thereafter the Soviets did not intervene again until June 1946, when the Chinese reached the northern part of Sinkiang where the uranium and beryllium deposits near Kashgar were located. There Soviet aircraft, artillery and ground troops stopped the Chinese offensive. Presumably this was to protect the supply of critical minerals used in the first Soviet atomic bomb but that is a matter of dispute among historians. What is beyond dispute is that the pro-Soviet Second East Turkestan Republic survived. Fighting spread east from Sinkiang towards Mongolia and by June 1947 reached regimental scale at Pei-ta-shan.

This is Stalin’s historical record. From Poland and the Baltics though Czechoslovakia and Iran to Sinkiang and Port Arthur it speaks for itself.

I now apply it to the Downfall scenario originated by DragonsInAmerica. Japan has not surrendered, and the war has continued past 14 August 1945. The million soldiers of the Kwangtung Army have been ordered to fight to the death. Instead of managing the surrender of 700,000 troops (another 300,000 fled to Korea or China in hopes of repatriation to Japan), the 1.5 million troops of the Manchurian Strategic Offensive Operation will begin to meet stiffening resistance from the Kwangtung Army. I have no doubts about the eventual Soviet victory, but I also have no doubt it will take longer than the 43 days IOTL to liquidate the Kwangtung Army. As I stated previously:

“Events have a momentum of their own. As the Soviets move deeper into Manchuria, local civil-military governments will be established to support and sustain further military advances.” I said Manchuria and I meant Manchuria – not China. The Soviets have to construct transportation networks depots for food, ammunition, fuel and all manner of other supplies airfields and their support structure repair facilities for equipment hospitals for the wounded – etc. To ensure this infrastructure, and their attendant lines of communication are kept secure, local civil-military governments will be established or else further advances cannot be sustained. This is true of every large scale military offensive.

I cannot say for certain how quickly the Soviet offensive will secure victory. I believe a minimum of 90 days for units to cover the 450-500 mile road distance to Harbin and then capture it. Another month will pass to consolidate and reconstitute frontline troops, and this time will also allow Soviet units advancing from the west along the Chinese Eastern Railway to reach Harbin. It is now winter, and the road network to support the offensive must still be expanded. Due to Lend-Lease, the Russians have the trucks and heavy equipment, but at the cost of delaying rehabilitating war damaged areas in Western Russia.

Despite the winter, the Soviet offensive may resume in February 1946, or four months after Japan’s refusal to surrender. During the next 60 days, Chi’angch’un, the next most important city in Manchuria is captured, an advance of nearly 200 more miles. More importantly, the flank area reaching to the Yalu River is cleared, permitting a large expansion of the Soviet toehold in Northern Korea. After another lull to restock logistical support follows with a resumption of the offensive in perhaps May 1946. The terrain is now more favorable, the weather allows Soviet air supremacy its full effectiveness, and the rate of resupply is increased. The Kwangtung Army is also severely degraded, whereas fresh Soviet troops are deployed as needed. The 300 miles to Mukden is covered in 30-45 days, and the 300 miles to Port Arthur in a similar time frame. The link-up with troops crossing Inner Mongolia is also achieved, and the Soviets halt in August 1946 at the Manchukuo borders. They are still over 150 miles from Peking or Tientsin. I doubt the Soviets will advance further.

During this time, other Japanese forces in China proper have been forced to retreat and consolidate. They no longer receive replacements from Japan, and forced to live off the land. The Nationalists will have probably reached Canton, and reopened a major port to supplies. The Communists were strongest in Shantung and in provinces to the west and southwest of Peking. The PLA has likely used the year between August 1945 and August 1946 to link those two regions, leaving Japanese forces isolated around Peking and the large plain reaching the Yellow Sea at Taku.

All of this is hypothetical. Depending on starvation levels of the number of atomic bombs used, Japan will eventually capitulate – certainly no later than mid-1947 if the fortunes of war fall their way sooner if not.

Here is the case for Stalin retaining Manchukuo.
1. The Soviets have paid for it in blood. Their casualties could be 100,000 – or higher.
2. The Soviets have sacrificed their recovery elsewhere to conquer it – Stalin must have some compensation to justify this.
3. The Soviets have established governments and civil authorities throughout Manchukuo and assumed the responsibilities that constitute sovereignty.
4. Manchukuo is therefore a legitimate spoil of war.
5. Manchukuo forms the land bridge to Korea, which in turn is a dagger pointed at the heart of Japan.
6. Between November 1944 and October 1945, Stalin ordered Project 72 aircraft carriers Project 24 battleships Project 82 battlecruisers Project 66 heavy cruisers Project 65 (later Project 68-bis) light cruisers and Project 30B destroyers to be constructed. They were to form powerful fleets for the Black Sea, Baltic, Arctic and Pacific. Neither Vladivostok nor Petropavlovsk is a suitable year-round base for the Pacific Fleet, but Port Arthur is.
7. Manchukuo’s vast resources are at the disposal of the USSR.
8. Stalin is a doctrinaire Communist. Expansion of Communism world-wide is an historical inevitability. It is arriving in Manchuria with the Soviet Army.
9. Mao Zedong was shabbily treated as a minor vassal by Stalin went he went to Moscow to seek economic aid in late 1949. I doubt he would receive better consideration in 1946.

I find the argument that Stalin would not act this way because he would be sensitive to the feelings of other nations unpersuasive.


Christian Bale could have done a 4th Batman movie — here’s why he didn’t

Posted On April 29, 2020 15:58:58

At the end of The Dark Knight Rises, Batman is not only alive but happily drinking wine with Anne Hathaway. It seems impossible, but it’s been 11 years since the final Christian Bale and Christopher Nolan Batman movie hit theaters. Since then, Ben Affleck has played Batman and now Robert Pattinson has slipped into the Batsuit for the highly anticipated 2021 film, The Batman. But what if it had all happened differently? What if Christian Bale had done one more turn as Batman?

Speaking to the Toronto Sun about his new film, Ford v. Ferrari, Bale makes it clear that a fourth Batman film was 100 percent in the cards, and certainly something Warner Bros. wanted from both him and director Christopher Nolan.

“Chris [Nolan] had always said to me that if we were fortunate to be able to make three we would stop,” Bale explains, saying the director always wanted it to be a trilogy, no matter what. Though Nolan and Bale always felt lucky each time they were able to make a new installment in their version of Batman. These days, we consider the Dark Knight trilogy to be a modern classic in the superhero genre movies that stand apart from the Marvel versus cinema debate. But, at the time, Bale points out that doing a new version of Batman was considered to be a fairly risky gamble.

Christian Bale in The Dark Knight Rises.

“I literally had people laugh at me when I told them we were doing a new kind of Batman,” Bale says. “I think that the reason it worked was first and foremost Chris [Nolan’s] take on it.”

Still, when the studio wanted a sequel to The Dark Knight Rises, Bale said Nolan turned it down. “Let’s not stretch too far and become overindulgent and go for a fourth…That’s why we, well Chris, stepped away. After that, I was informed my services were no longer required.”

Though this interview makes it sound like Bale was in solidarity with Nolan, that last detail also suggests he would have done another Batman movie in a different capacity if asked. Though Christopher Nolan produced The Man of Steel and Batman eventually appeared in its sequel, Batman v. Superman, it’s an interesting thought experiment to consider what would have happened if it was Bale’s Batman and not Ben Affleck who battled with Superman? It’s an alternate dimension we’ll never visit one starring a Batman that we didn’t need, per se, but certainly, the Batman we still think we all deserve.

This article originally appeared on Fatherly. Follow @FatherlyHQ on Twitter.

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MIGHTY TACTICAL

Ketsu-Go

Meanwhile, the Japanese had their own plans. Initially they were concerned about an invasion during the summer of 1945. However, the Battle of Okinawa went on so long that they concluded the Allies would not be able to launch another operation before the typhoon season, during which the weather would be too risky for amphibious operations. Japanese intelligence predicted fairly closely where the invasion would take place: southern Kyushu at Miyazaki, Ariake Bay, and/or the Satsuma Peninsula. While Japan no longer had a realistic prospect of winning the war, it could perhaps raise the cost of conquering Japan too high for the Allies to accept, leading to some sort of armistice. The Japanese plan for defeating the invasion was called Ketsu-Go, "Decisive Operation".

Kamikazes

The Japanese defense relied heavily on kamikaze planes. In addition to fighters and bombers, they reassigned almost all of their trainers for the mission, trying to make up in quantity what they lacked in quality. Between them, the Army and Navy had more than 10,000 aircraft ready for use in July, and would have had somewhat more by October&mdashand were planning to use almost all that could reach the invasion fleets.

During the Battle of Okinawa, less than 2,000 kamikazes had gotten about one hit per nine planes that made an attack. At Kyushu, given the more favorable circumstances, they hoped to get one for six. The Japanese estimated that the planes would sink more than 400 ships, and since they were training the pilots to target transports rather than carriers and destroyers, the casualties would be disproportionately greater than at Okinawa. One staff study estimated that the kamikazes could destroy a third to a half of the invasion force before its landings.

Naval forces

The Imperial Japanese Navy no longer had any ships available larger than destroyers. By August they did have about 100 Koryu-class midget submarines, 250 smaller Kairyu-class midget submarines, and 1,000 Kaiten manned torpedoes. The Japanese Army had 800 Shinyo suicide boats.

Ground forces

In any amphibious operation, the defender has two choices for defensive strategy&mdashstrong defense of the beaches, or defense in depth. Early in the war (such as at Tarawa) the Japanese employed strong defenses on the beaches themselves, with little or no manpower in reserve. This tactic proved to be very vulnerable to pre-invasion shore bombardment. Later in the war, at Peleliu, Iwo Jima, and Okinawa, the Japanese switched strategy and dug in their forces in the most defensible terrain. Fighting degenerated into long battles of attrition, with very high American casualties, but no hope of victory for the Japanese.

For the defense of Kyushu, the Japanese took an intermediate posture, with the bulk of their defensive forces a few km inland from the shore&mdashback far enough to not be completely exposed to naval gunnery, but close enough that the Americans could not establish a secure foothold before engaging them. The counteroffensive forces were still further back, prepared to move against whichever landing seemed to be the main effort.

In March 1945, there was only one combat division in Kyushu. Over the next four months the Japanese Army transferred forces from Manchuria, Korea, and northern Japan, while raising other forces in place. By August, they had fourteen divisions and various smaller formations, including three tank brigades, for a total of 900,000 men.

The Japanese were able to raise large numbers of new soldiers, but equipping them was harder. By August, the Japanese Army had the equivalent of 65 divisions in the homeland, but only enough equipment for 40, and only enough ammunition for 30. The Japanese did not formally decide to stake everything on the outcome of the Battle of Kyushu, but they concentrated their assets to such a degree that there would be little left in reserve. By one estimate, the forces in Kyushu had 40% of all the ammunition in the Home Islands.

In addition, the Japanese had organized nearly all adult civilians into the Patriotic Citizens Fighting Corps to perform combat support, and ultimately combat jobs. Weapons and training were generally lacking, but they were expected to make do with what they had.

One mobilized high school girl, Yukiko Kasai, found herself issued an awl and told, "Even killing one American soldier will do. . You must aim for the abdomen." (Richard B. Frank, Downfall)


World War II in the Pacific Operation Downfall: Olympic, Coronet The Invasion of Japan

Olympic entailed landing three corps on southern Kyushu, the most southern of the four Japanese home islands. The center portion of Kyushu is almost impassible mountains which would be difficult to transit and was to be used to isolate southern Kyushu from counterattack by Japanese troops from northern Kyushu (Nagasaki). The landings were to be by troops already in the Pacific covered by 34 carriers and by land based aircraft from Okinawa. B-29's would interdict reinforcements. Southern Kyushu had a large bay, harbors, and many airfields. The intent was to base naval support craft and to establish 40 air groups, many redeployed from Europe. From southern Kyushu, fighter air cover could open the Inland Sea to the US Navy and interdict transportation as far as north as Osaka fighter bombers could close shipping from Korea and China medium bombers and could destroy transportation, material, and installations around Tokyo and support the invasion troops large bombers (B-17 and B-24) could range over all of Japan. Meanwhile, B-29's from the Marianas could continue to wipe out industrial centers.

There were two naval groups.
The Strike Force, 3rd Fleet, had 21 carriers and 10 fast battleships to range up and down the length of Japan to suppress Japanese forces with priority to destroy aircraft and transportation.
The Assault Force, 5th Fleet, had 26 carriers, plus 8 detached from Strike force for the invasion period, 13 slow battleships, 20 cruisers, 139 DD, 167 DE, and support ships for a total of 800 warships. Troops and their equipment were to come from the Philippines and Marianas in 1,500 transports. All troops were from the Pacific theater none redeployed from Europe. The plan called for a diversionary display by the floating reserve on Shikoku, the smallest of Japan's four islands, before their landing on Kyushu.

  • Kamikazes -- 2,100 army planes and 2,700 navy planes.
  • Baku - suicide missile carried by a bomber.
  • Mini-subs, each with 2 torpedoes, 500 were building.
  • Fleet submarines -- arm the 57 remaining that had been dedicated to resupply of outposts.
  • Kaiten - suicide torpedoes with a 20 mile range.
  • Shinyo - suicide motorboats. The army had 1-man, 17 foot motorboats. The navy had 2-man, 22 foot boats.
  • The largest surviving warships were destroyers that were prepared for suicidal attack on the invasion convoys.
  • On the land, human mines in which soldiers had explosives strapped to their bodies and were to crawl under a tank. Other explosives were packed with a suction cup to be attached to the side of a tank. And shaped charges on a long pole were to be detonated on the side of a tank.
  • Paratroopers were to attack Okinawa to disrupt flight operations during the invasion period.

A plan resurrected after the enemy buildup on Kyushu exceeded all expectations, was the occupation of the less well defended northern island of Hokkaido and northern part of Honshu. This would have been of equal distance from Tokyo, but further from American army, naval, and air force centers. Shipping was already a problem with large numbers unreleased from the Atlantic needed to supply Europe and return troops to the US, to redeploy air and service forces from Europe to the Pacific, to supply the Pacific buildup and to move several corps to the invasion sites. Every tanker in the US fleet was required to provide the millions of gallons of fuel required by the ships involved in the Kyushu operation. More fuel and shipping would be required to move 1,100 miles further away to the north.


Exclusive* Operation Downfall "CONFIDENTIAL" U.S. Aerial Reconnaissance Squadron Photograph - Secret Planning of Operation Coronet

This extremely rare “CONFIDENTIAL” marked U.S. aerial reconnaissance photograph is titled “Mito Area, Honshu” and was taken to be utilized in the Allied strategic planning of what would be Operation Downfall. Operation Downfall was the proposed Allied plan for the invasion of the Japanese Home Islands near the end of World War II. The operation had two parts: Operation Olympic and Operation Coronet. Set to begin in November 1945, Operation Olympic was intended to capture the southern third of the southernmost main Japanese island, Kyūshū, with the recently captured island of Okinawa to be used as a staging area. In early 1946 would come Operation Coronet, the planned invasion of the Kantō Plain, near Tokyo, on the main Japanese island of Honshu. Airbases on Kyūshū captured in Operation Olympic would allow land-based air support for Operation Coronet. If Downfall had taken place, it would have been the largest amphibious operation in history. The planned operation was cancelled when Japan surrendered following the atomic bombings of Hiroshima and Nagasaki.

This extremely large aerial photograph was taken by an unknown secret aerial reconnaissance squadron flying over the Japanese occupied and heavily defended island of Honshu. This photograph not only depicts a clear aerial view of the land below, but it is strategically labeled with the exact markings as seen on U.S. target maps representing Japanese pill boxes, observation towers, artillery placements, radio towers, etc. The Japanese defensive positions and markings made on this intelligence photograph show that this aerial photograph was used in the strategic planning of the Japanese port city and would have played a crucial intelligence roll for the United States Navy, Air Corps, and infantry as they invaded the Japanese homeland.

Invasion of the Homeland (and Honushu):

While the war was being fought in the Philippines and Okinawa, plans were ripening rapidly for the largest amphibious operation in the history of warfare. "Downfall," the grand plan for the invasion of Japan, contemplated a gargantuan blow against the islands of Kyushu and Honshu, using the entire available combined resources of the army, navy, and air forces.

The plans for "Downfall" were first developed early in 1945 by the Combined Chiefs of Staff at the Argonaut Conference held on the tiny island of Malta in the Mediterranean. On 9 February, just a few days before the historic Three-Power meeting at Yalta, President Roosevelt and Prime Minister Churchill were informed of the conclusions reached at Argonaut. At that time, the strategic concept of future operations in the Pacific embodied the defeat of Japan within eighteen months after Germany's surrender and included the following series of proposed objectives:

a. Following the Okinawa operation, to seize additional positions to intensify the blockade air bombardment of Japan in order to create a situation favorable to:

b. An assault on Kyushu for the purpose of further reducing Japanese capabilities by containing and destroying major enemy forces and further intensifying the blockade and air bombardment in order to establish a tactical condition favorable to:

c. The decisive invasion of the industrial heart of Japan through the Tokyo Plain.

On 29 March, the U.S. Joint Chiefs of Staff, working on the assumptions that the war in Europe would be over by 1 July 1945 and that the forthcoming Okinawa operation would be concluded by mid-August of 1945, set a tentative schedule for the invasion of Japan. The invasion plan was assigned the cover name "Downfall" and consisted of two main operations: "Olympic," the preliminary assault on the southern island of Kyushu, which was slated for 1 December 1945, and "Coronet," the subsequent landing on Honshu, which was scheduled for 1 March 1946. (Plate No. 112) It was proposed that forces already in the Pacific be used to the fullest extent possible in planning for the assault and follow-up phases of "Olympic." Reserve and follow-up divisions for "Coronet" would be obtained by redeployment, either directly or via the United States, of troops and equipment from the European Theater.

On 3 April 1945, the Joint Chiefs of Staff issued a directive in which General MacArthur was instructed to complete the necessary operations in Luzon and the rest of the Philippines, prepare for the occupation of North Borneo, and "make plans and preparations for the campaign in Japan." The amphibious and aerial phases of the projected Homeland invasion.


Watch the video: Slavs vs Anime - Ukraine invades Japan Operation Downfall in HOI4 (January 2022).