What was the name of the planned Allied invasion of Japan’s main islands in 1945?

Operation Downfall was the planned Allied invasion of Japan’s main islands in 1945.

The plan was divided into two major stages. Operation Olympic called for an invasion of southern Kyushu, while Operation Coronet envisioned a later assault on Honshu near Tokyo. Downfall was the overall name for both operations.

Operation Olympic was scheduled for November 1945, and Coronet was planned for March 1946. Allied planners expected fierce resistance because Japan had prepared defensive forces, civilian militias, aircraft, small boats, and other weapons for a homeland battle.

The invasion was never carried out. Japan announced acceptance of the Potsdam Declaration in August, and the formal surrender followed in September. Because Downfall remained a plan rather than an executed campaign, estimates of possible casualties vary widely and should not be presented as actual losses.