What was the codename for the planned Allied invasion of Japan that was avoided after surrender?

Operation Downfall was the codename for the planned Allied invasion of Japan that was avoided after surrender.

The proposed operation had two major phases. Operation Olympic was planned for the invasion of Kyushu in November 1945, while Operation Coronet was planned for the assault on Honshu near Tokyo in March 1946. Together, these phases formed Operation Downfall.

Allied planners expected fierce resistance. Japan had mobilized military forces and civilians for homeland defense, while the Allies assembled large numbers of troops, ships, and aircraft. The projected casualties were debated extensively, and no single agreed total existed because estimates depended on assumptions about Japanese resistance and the scale of the invasion.

The atomic bombings of Hiroshima and Nagasaki, the Soviet entry into the war, and Japan's decision to surrender made the invasion unnecessary. Operation Downfall was never carried out. Olympic and Coronet therefore remain names for planned operations rather than battles that occurred.