What was the Allied plan for a full-scale invasion of Japan before its 1945 surrender?

Operation Downfall was the Allied plan for a full-scale invasion of Japan before its 1945 surrender.

The proposed operation had two major stages. Operation Olympic would have invaded Kyushu in November 1945, while Operation Coronet would have attacked Honshu near Tokyo in March 1946. Together, these operations were intended to force Japan’s surrender through the capture of key territory and political centers.

Downfall was never carried out because Japan accepted the Allied surrender terms in August 1945. The plan’s projected casualties were heavily debated, although estimates varied widely and depended on assumptions about Japanese resistance, civilian mobilization, and the scale of Allied forces.

The planned invasion is sometimes confused with Operation Olympic, but Olympic was only the first phase of Downfall. Operation Overlord, by contrast, was the Allied invasion of Normandy in Europe in June 1944.