What was the planned 1946 Allied invasion of Japan’s Kanto Plain called?

The planned 1946 Allied invasion of Japan’s Kanto Plain was called Operation Coronet.

Coronet was the second stage of Operation Downfall, the proposed Allied invasion of the Japanese home islands. It was tentatively scheduled to begin on 1 March 1946, after Operation Olympic had captured territory in southern Kyushu. Coronet would have targeted the Kanto Plain near Tokyo on Honshu, Japan’s largest main island.

The plan envisioned landings by the U.S. First Army and Eighth Army, followed by large reinforcements. Up to 45 U.S. divisions were associated with the wider Coronet commitment, making it potentially larger than the initial Normandy landings in personnel and scope.

Coronet was never launched because Japan surrendered in August 1945. Operation Olympic and Operation Coronet are often confused because both belonged to Operation Downfall: Olympic concerned Kyushu, while Coronet concerned the Tokyo region.