What was the planned Allied invasion of Japan called if the country did not surrender in 1945?

Operation Downfall was the planned Allied invasion of Japan if the country did not surrender in 1945.

The operation was the overall plan for invading the Japanese home islands. It had two major phases: Operation Olympic, aimed at southern Kyushu, and Operation Coronet, aimed at the Tokyo Plain on Honshu. Olympic was scheduled for November 1945, while Coronet was planned for March 1946.

The invasion was never carried out because Japan accepted the Potsdam Declaration and formally surrendered. Allied planners expected extremely heavy casualties because Japanese forces were preparing for a decisive defense of the homeland, and civilians were also being organized for resistance.

Operation Downfall is sometimes confused with its component operations. Downfall was the umbrella plan; Olympic and Coronet were its two principal stages. It is also distinct from Operation Overlord, the Allied invasion of Normandy in June 1944. The unused plans illustrate how close the war’s final outcome was to a potentially much larger campaign.