What was the codename for the planned Allied invasion of Japan if its 1945 surrender had not occurred?

Operation Downfall was the codename for the planned Allied invasion of Japan if its 1945 surrender had not occurred.

Downfall was the proposed invasion of the Japanese home islands. It was divided into two major stages: Operation Olympic, the planned assault on Kyushu scheduled for November 1945, and Operation Coronet, the planned invasion of Honshu near Tokyo scheduled for March 1946. These operations were never launched because Japan surrendered in August 1945.

Allied planners expected the invasion to be extremely costly. Japan had prepared defensive forces, aircraft, naval units, and civilian resistance plans. The United States also made preparations for a large buildup of troops and equipment for the operation. Estimates of possible casualties varied widely, and historians continue to debate how the invasion plans influenced the decision to use atomic bombs and seek surrender.

Operation Overlord was different: it was the Allied invasion of Normandy in June 1944. Operation Torch was the 1942 Allied landing in French North Africa, so neither name applies to the proposed invasion of Japan.