What was the planned 1946 Allied operation to invade Japan’s Kantō Plain near Tokyo?

Operation Coronet was the planned 1946 Allied invasion of Japan’s Kantō Plain near Tokyo.

Coronet was intended to be the second stage of Operation Downfall. After Operation Olympic seized southern Kyushu, Coronet would have landed forces on the Kantō Plain, the broad lowland surrounding Tokyo and Yokohama on Honshu. The tentative date was March 1, 1946.

The planned assault was expected to be even larger than Olympic. The U.S. First Army and Eighth Army were assigned major landing roles, with initial objectives including beaches near Kujūkuri and Hiratsuka. Reinforcements would then advance toward Tokyo and the surrounding political and industrial centers.

Japan’s surrender in August 1945 canceled both stages. Coronet is therefore a planned operation, not a battle that occurred. The names are easy to mix up: Olympic referred to Kyushu, Coronet to the Kantō Plain, and Downfall to the overall invasion plan.