What was the Allied plan for invading Japan’s home islands in late 1945 and 1946?

Operation Downfall was the Allied plan for invading Japan’s home islands in late 1945 and 1946.

The proposed operation had two major phases. Operation Olympic was scheduled to land on southern Kyushu in November 1945. Operation Coronet was planned for spring 1946 against the Kanto Plain near Tokyo on Honshu.

Downfall was canceled after Japan accepted the Allied surrender terms. The atomic bombings, the Soviet declaration of war and invasion of Manchuria, Japan’s military situation, and the Emperor’s decision all preceded the cancellation.

The planned invasion was expected to be extraordinarily costly. Allied and Japanese casualty estimates varied widely, and no single agreed figure existed. Operation Downfall is therefore not a battle that occurred; it was a contingency plan whose projected campaigns were never launched.