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

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

The plan consisted of two major stages. Operation Olympic would have invaded southern Kyushu in November 1945, while Operation Coronet was planned for the Kanto Plain near Tokyo in March 1946.

Downfall was developed because Allied leaders expected Japan to resist an invasion fiercely. Military planners prepared for enormous casualties, drawing on the fighting at Iwo Jima and Okinawa and on Japan’s preparations for homeland defense.

Japan’s surrender in August 1945 made the invasion unnecessary. The atomic bombings, Soviet entry into the war, Japan’s military position, and internal political decisions all contributed to the end of the conflict before Downfall began.