Which two operations made up the proposed Allied invasion plan known as Operation Downfall?

Operation Downfall consisted of Operation Olympic and Operation Coronet.

Olympic was the first planned stage, targeting southern Kyūshū in November 1945. Its purpose was to capture territory and airfields that could support the later invasion of Japan’s main island. Coronet was the second stage, planned for spring 1946 against the Kantō Plain near Tokyo on Honshū.

The plan was developed because Allied leaders feared that Japan might refuse to surrender. It required enormous naval, air, and ground forces and was expected to become the largest amphibious operation in history if carried out.

Downfall was canceled after Japan accepted the Potsdam Declaration in August 1945. Operation Pastel was a deception plan connected to Olympic, while Ketsugō was Japan’s defensive strategy for resisting an invasion. Those names are therefore related to Downfall but were not its two principal operations.