What Allied invasion plan for Japan was rendered unnecessary by Japan’s surrender?

Operation Downfall was the Allied invasion plan for Japan rendered unnecessary by Japan’s surrender.

Downfall was the proposed invasion of the Japanese home islands. It had two major stages: Operation Olympic, the planned invasion of Kyushu, and Operation Coronet, the proposed assault on Honshu near Tokyo. Olympic was scheduled for November 1945, while Coronet was planned for March 1946.

The plan was never carried out. Japan’s surrender in August 1945 followed the atomic bombings of Hiroshima and Nagasaki, the Soviet declaration of war, and the emperor’s decision to accept the Potsdam Declaration. The formal surrender was signed on September 2.

Operation Iceberg, by contrast, was the codename for the 1945 invasion of Okinawa, which did occur. Olympic and Coronet were components of Downfall, so listing either as the overall plan is a common mix-up.