Operation Olympic was the codename for the planned Allied invasion of Kyushu if Japan had not surrendered in 1945.
Olympic was the first stage of Operation Downfall, the proposed invasion of Japan's home islands. Allied planners scheduled the landing for November 1, 1945, with Kyushu as the initial objective. The operation would have established bases and reduced Japanese resistance before a later assault on the main island of Honshu.
The second stage, Operation Coronet, was planned for the Kanto Plain near Tokyo on March 1, 1946. Neither operation took place because Japan accepted the Potsdam Declaration and formally surrendered in September 1945.
Planning for Olympic involved enormous logistical preparations, including troop movements, naval support, air operations, and estimates of Japanese civilian and military resistance. The projected casualties remain the subject of historical debate, but the operation itself was cancelled rather than launched.