What was the planned Allied invasion of Japan, canceled after Japan surrendered in 1945, called?

The planned Allied invasion of Japan, canceled after Japan surrendered in 1945, was called Operation Downfall.

Downfall was the overall plan for invading the Japanese home islands if the government refused to capitulate. It had two principal stages. Operation Olympic would have attacked Kyushu, the southernmost of Japan’s four main islands, while Operation Coronet would have followed with an assault on Honshu near Tokyo.

American planners expected fierce resistance because Japan had concentrated troops, aircraft, naval craft, and civilian defense preparations on the home islands. The invasion plans were therefore connected to difficult estimates of casualties and the timing of additional reinforcements. Olympic was provisionally scheduled for November 1945, with Coronet planned for the following year.

Japan’s acceptance of the Potsdam Declaration made Downfall unnecessary. The atomic bombings, the Soviet entry into the war, blockade, conventional bombing, and internal Japanese political decisions all formed part of the complex context surrounding surrender.