What was the name of the planned Allied invasion of Japan if Japan did not surrender in 1945?

Operation Downfall was the planned Allied invasion of Japan if Japan did not surrender in 1945.

The plan had two main stages. Operation Olympic called for an invasion of southern Kyushu, while Operation Coronet proposed a later assault on the Kantō Plain near Tokyo. Together, these operations were part of the larger Downfall plan.

Planning reflected Allied expectations that Japan’s home islands would be defended intensely. Japanese military leaders were preparing civilians and soldiers for a decisive battle, and Allied planners anticipated very heavy casualties.

Japan’s acceptance of the Allied surrender terms meant Downfall was never carried out. The atomic bombings, the Soviet declaration of war, Japan’s military situation, and internal political decisions all formed part of the rapidly changing circumstances that ended the war before the invasion date.