Operation Downfall - Planning

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). 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. 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.

Throughout the Pacific War, the Allies were 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.