What was the planned Allied invasion of the Japanese home islands called?

The planned Allied invasion of the Japanese home islands was called Operation Downfall.

Downfall was the overall plan for invading Japan if the country did not surrender. It included Operation Olympic, the proposed invasion of southern Kyushu, and Operation Coronet, the planned assault on the Tokyo Plain near Honshu.

Olympic was scheduled for November 1945, while Coronet was projected for March 1946. Allied planners expected fierce resistance, including attacks by kamikaze aircraft and the mobilization of Japanese military and civilian defenders.

Japan’s surrender made the invasion unnecessary. Operation Downfall is therefore often confused with Olympic or Coronet, but those were component operations within the larger plan. The plan illustrates why the prospect of surrender was linked to fears of a devastating invasion and enormous casualties on both sides.