What was the proposed overall Allied invasion plan for Japan called in 1945?

The proposed overall Allied invasion plan for Japan was called Operation Downfall.

Downfall was designed as a two-stage invasion of the Japanese home islands. Operation Olympic would have attacked southern Kyushu, while Operation Coronet would have followed with an invasion of the Kanto Plain near Tokyo. Olympic was scheduled to begin on November 1, 1945, with Coronet planned for spring 1946.

The plan was never carried out because Japan surrendered in August 1945. The atomic bombings of Hiroshima and Nagasaki, the Soviet declaration of war, and Japan’s internal surrender decision ended the need for a mainland invasion.

Operation Downfall is often confused with its component operations. Olympic referred specifically to the Kyushu assault, and Coronet referred to the later Honshu operation. Japan’s defensive response was called Operation Ketsugō. Had Downfall occurred, planners expected an enormous amphibious campaign with very high casualties on both sides.