What was the codename for the planned Allied invasion of Japan that never occurred?

Operation Downfall was the codename for the planned Allied invasion of Japan that never occurred.

The plan was divided into two major stages. Operation Olympic would have invaded Kyushu in November 1945, while Operation Coronet was scheduled to attack Honshu near Tokyo in March 1946.

Japan’s surrender in August 1945 made the invasion unnecessary. The atomic bombings of Hiroshima and Nagasaki, the Soviet declaration of war, and Japan’s internal decision to accept the Allied terms all occurred before the invasion began.

Operation Downfall is sometimes confused with Operation Olympic, but Downfall was the overall invasion plan. Olympic was the first phase, and Coronet was the second. Estimates of possible casualties varied widely, which has made the operation central to debates about the final months of the Pacific War.