What was the first stage of the proposed Operation Downfall invasion of Japan?

Operation Olympic was the first stage of the proposed Operation Downfall invasion of Japan.

Olympic was intended to seize the southern part of Kyūshū, the southernmost of Japan's four main islands. The Allies planned to use airfields captured there to support the later stage, Operation Coronet, which would target the Kantō Plain near Tokyo on Honshū.

The operation was scheduled to begin in November 1945. Okinawa, captured by the Allies in June 1945 after a costly campaign, was to serve as a major staging area for the invasion. Allied planners expected fierce resistance because Japanese forces were organizing a nationwide defense against an anticipated landing.

Japan surrendered before Olympic began. The planned invasion is therefore a counterfactual military operation rather than a battle. It is also distinct from Operation Neptune, the naval and airborne component of the Normandy invasion in Europe, and Operation Husky, the Allied invasion of Sicily in 1943.