Operation Downfall

Operation Downfall was the proposed plan by United States and British Empire forces for the invasion of the Japanese home islands near the end of World War II. It was canceled when Japan surrendered following the atomic bombings of Hiroshima and Nagasaki and the Soviet declaration of war on Japan and invasion of Manchuria.

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 Spring 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, surpassing D-Day.