What was the planned second phase of Operation Downfall, aimed at Japan’s Kanto Plain?

Operation Coronet was the planned second phase of Operation Downfall, aimed at Japan’s Kanto Plain.

The Kanto Plain surrounds Tokyo and lies on Honshu, Japan’s largest main island. Coronet was intended to follow Operation Olympic, the proposed invasion of southern Kyushu, and was tentatively scheduled for March 1, 1946.

The plan called for major American armies to land near the Kanto region and advance toward Tokyo. It would have required an enormous concentration of personnel, ships, aircraft, and supplies, making it one of the largest planned amphibious operations in history.

Coronet was canceled because Japan surrendered in August 1945. The operation is often confused with Downfall, but Downfall was the overall invasion plan, while Coronet was its proposed second phase.