What was the Allied plan to invade Japan’s home islands in late 1945 and 1946 called?

The Allied plan to invade Japan’s home islands in late 1945 and 1946 was called Operation Downfall.

Downfall was a proposed United States and British Empire operation that would have followed Japan’s refusal to surrender. It had two principal stages: Operation Olympic, planned for southern Kyūshū in November 1945, and Operation Coronet, planned for the Kantō Plain near Tokyo in spring 1946.

The invasion plan was canceled after Japan accepted the Allied terms in August 1945. The atomic bombings of Hiroshima and Nagasaki, the Soviet declaration of war, and the resulting strategic situation all contributed to Japan’s surrender before Downfall began.

Operation Downfall is often confused with Operation Overlord, the Allied invasion of Normandy in 1944. Overlord occurred in Europe; Downfall was the unrealized plan for the Japanese home islands and would have been one of history’s largest amphibious operations.