What was the codename for the planned 1946 Allied invasion of the Kanto Plain near Tokyo?

The planned 1946 Allied invasion of the Kanto Plain near Tokyo was codenamed Operation Coronet.

Coronet was the second stage of Operation Downfall, the wider plan to invade Japan. It was tentatively scheduled to begin on 1 March 1946, after Operation Olympic had captured southern Kyushu and provided additional air bases. The intended landing area was the Kanto Plain on Honshu, Japan’s largest island.

The operation would have aimed at the Tokyo region and was expected to require a very large concentration of Allied forces. Its projected scale reflected the strategic importance of the Japanese capital and the expectation of fierce resistance.

Coronet never took place. Japan announced its acceptance of the Allied terms in August 1945 and signed the formal surrender on 2 September. Coronet is therefore not a battle name or a surrender ceremony name; it was a proposed future invasion operation.