Operation Downfall

Operation Downfall was the codename for the Allied plan for the invasion of Japan near the end of World War II. The planned operation was abandoned when Japan surrendered after the atomic bombings of Hiroshima and Nagasaki. The operation had two parts: Operation Olympic and Operation Coronet. Set to begin in October 1945, Operation Olympic was intended to capture the southern third of the southernmost main Japanese island, Kyushu, with the recently captured island of Okinawa to be used as a staging area. Later, in spring 1946, Operation Coronet was the planned invasion of the Kanto Plain, near Tokyo, on the Japanese island of Honshu. Airbases on Kyushu captured in Operation Olympic would allow land-based air support for Operation Coronet. Japan's geography made this invasion plan quite obvious to the Japanese as well; they were able to predict the Allied invasion plans accurately and thus adjust their defensive plan, Operation Ketsugo, accordingly. The Japanese planned an all-out defense of Kyushu, with little left in reserve for any subsequent defense operations. Casualty predictions varied widely but were extremely high for both sides: depending on the degree to which Japanese civilians resisted the invasion, estimates ran into the millions for Allied casualties[1] and several times that number for total Japanese casualties. Planning Responsibility for planning Operation Downfall fell to the U.S. commanders: Fleet Admiral Chester Nimitz, General of the Army Douglas MacArthur and the Joint Chiefs of Staff—Fleet Admirals Ernest King and William D. Leahy, and Generals of the Army George Marshall and Hap Arnold (the latter was commander of the U.S. Army Air Forces).[2] Douglas MacArthur at the time was also being considered for promotion to a special "super rank" of General of the Armies, so as to be granted operational authority over other five star officers.[3] However, the proposal to promote MacArthur was only at the level of informal discussion when World War II ended. At the time, the development of the atomic bomb was a very closely guarded secret (not even then Vice President Harry Truman knew of its existence until he later became President), known only to a few top officials outside the Manhattan Project and the initial planning for the invasion of Japan did not take its existence into consideration. Once the atomic bomb became available, General Marshall envisioned using it, if sufficient numbers could be produced in time, to support the invasion.[4] Throughout the Pacific War, the Allies

ere unable to agree on a single Commander-in-Chief (C-in-C). Allied command was divided into regions: by 1945, for example, Chester Nimitz was Allied C-in-C Pacific Ocean Areas, while Douglas MacArthur was Supreme Allied Commander, South West Pacific Area, and Admiral Louis Mountbatten was Supreme Allied Commander, South East Asia Command. A unified command was deemed necessary for an invasion of Japan. Inter-service squabbling over who it should be (the US Navy wanted Nimitz, but the US Army wanted MacArthur) was so serious that it threatened to derail planning. Ultimately, the Navy partially conceded, and MacArthur was to have total command of all forces, if circumstances made it necessary.[5] [edit]Considerations The primary considerations that the planners had to deal with were time and casualties—how they could force Japan's surrender as quickly as possible, with as few Allied casualties as possible. Prior to the 1943 Quebec Conference, a joint British-American planning team produced a plan ("Appreciation and Plan for the Defeat of Japan") which did not call for an invasion of the Japanese home islands until 1947–1948.[6][7] The American Joint Chiefs of Staff believed that prolonging the war to such an extent was dangerous for national morale. Instead, at the Quebec conference, the Combined Chiefs of Staff agreed that Japan should be forced to surrender not more than one year after Germany's surrender. The US Navy urged the use of blockade and airpower to bring about Japan's capitulation. They proposed operations to capture airbases in nearby Shanghai, China, and Korea, which would give the US Army Air Forces a series of forward airbases from which to bombard Japan into submission.[8] The US Army, on the other hand, argued that such a strategy could "prolong the war indefinitely" and expend lives needlessly, and therefore that an invasion was necessary. They supported mounting a large-scale thrust directly against the Japanese homeland, with none of the side operations that the Navy had suggested. Ultimately, the Army's viewpoint won.[9] Physically, Japan made an imposing target, with very few beaches geographically suitable for sea-borne invasion. Only Kyushu (the southernmost island of Japan) and the beaches of the Kanto plain (both southwest and southeast of Tokyo) were realistic invasion zones. The Allies decided to launch a two-stage invasion. Operation Olympic would attack southern Kyushu. Airbases would be established, which would give cover for Operation Coronet, the attack on Tokyo Bay.