What was the first phase of the planned Allied invasion of Japan, scheduled for Kyūshū?

Operation Olympic was the first phase of the planned Allied invasion of Japan, targeting the southern island of Kyūshū. It was scheduled for 1 November 1945 but was never carried out.

Olympic formed the southern part of Operation Downfall, the overall Allied plan for invading the Japanese home islands. The second phase, Operation Coronet, was planned for the Kantō Plain near Tokyo in March 1946. Allied planners expected Olympic to establish airfields and beachheads that would support the later advance toward the capital.

The invasion plans were developed because Japan had not yet accepted the Allied demand for surrender. American planners anticipated fierce resistance, drawing on the battles of Iwo Jima and Okinawa and preparations for a mass defense of the home islands.

Japan’s surrender made both Olympic and Coronet unnecessary. The atomic bombings of Hiroshima and Nagasaki, the Soviet entry into the war, and political decisions by Japan’s leadership combined to end the conflict before the invasion date. Operation Downfall therefore remained a plan rather than a battle, although its projected casualties influenced wartime discussions.