What U.S. plan was prepared for a possible invasion of the Japanese home islands in 1945?

Operation Downfall was the U.S. plan prepared for a possible invasion of Japan’s home islands in 1945.

The plan had two major stages. Operation Olympic called for an invasion of Kyushu, scheduled for November 1945, while Operation Coronet envisioned an assault on Honshu near Tokyo in March 1946. Together, these operations formed Operation Downfall.

The invasion was never carried out because Japan surrendered before Olympic began. The atomic bombings, the Soviet entry into the war, Japan’s worsening military position, and the Emperor’s intervention all contributed to the end of the conflict before the planned landings.

Operation Downfall is sometimes used as though it were the name of the first landing alone. That is incorrect: Olympic and Coronet were the component operations, while Downfall was the overall invasion concept. The plan’s projected casualties remain a subject of historical debate because estimates varied widely and depended on assumptions about Japanese resistance.