What was the Allied codename for the planned invasion of Japan in 1945?

Operation Downfall was the Allied codename for the planned invasion of Japan in 1945.

The plan was designed for a possible invasion if Japan did not surrender. It had two major stages: Operation Olympic, the proposed assault on Kyushu scheduled for November 1945, and Operation Coronet, the planned invasion of Honshu near Tokyo scheduled for March 1946.

Operation Downfall would have required enormous Allied forces and was expected to produce severe casualties. Japanese military leaders also prepared defensive plans and mobilized civilians for a possible invasion of the home islands.

Japan’s acceptance of the Allied surrender terms in August 1945 meant that Downfall was never launched. The atomic bombings of Hiroshima and Nagasaki, the Soviet entry into the war against Japan, the naval blockade, conventional bombing, and Japan’s internal decision-making all formed part of the complex context of the surrender. Downfall is therefore a planned operation, not a battle that actually occurred.