Operation Downfall was the planned Allied invasion of Japan that became unnecessary after Japan surrendered. It was the overall plan for a massive invasion of the Japanese home islands in late 1945 and 1946.
Downfall consisted of two major stages. Operation Olympic was planned for the invasion of southern Kyushu in November 1945, while Operation Coronet was planned for the invasion of Honshu near Tokyo in March 1946.
The surrender in August 1945 ended the need to carry out the plan. Operation Downfall is often discussed in connection with debates about the atomic bombings, the Soviet entry into the war, Japanese resistance, and projected Allied casualties, but the invasion itself never occurred.