What was the name of the proposed Allied invasion plan for Japan in 1945?

Operation Downfall was the proposed Allied invasion plan for Japan in 1945.

The plan was divided into two major stages. Operation Olympic would have invaded southern Kyushu in November 1945, while Operation Coronet would have attacked the Tokyo Plain in March 1946. Together, these operations formed the larger Operation Downfall.

The plan was prepared because Allied leaders expected Japan to continue fighting despite military defeat. Japanese authorities were also organizing a large-scale defense of the home islands, including civilian mobilization. Allied planners anticipated severe casualties and logistical challenges, although estimates varied and later popular accounts sometimes present disputed figures as settled facts.

Operation Downfall was never carried out. Japan’s acceptance of the Potsdam Declaration, following the atomic bombings and the Soviet entry into the war, removed the need for an invasion. The occupation instead began under the terms of Japan’s surrender, with General Douglas MacArthur serving as Supreme Commander for the Allied Powers.