What was the planned Allied operation to invade Japan’s main island of Honshu in 1945 called?

Operation Coronet was the planned Allied operation to invade Japan’s main island of Honshu in 1945.

Coronet was the second phase of Operation Downfall, the proposed invasion of the Japanese home islands. It was planned as a massive landing near Tokyo on Honshu, following Operation Olympic, which would have targeted southern Kyushu.

The operation was never carried out because Japan surrendered in August 1945. The planned invasion therefore remains a counterfactual military operation rather than a battle that occurred. Allied planners expected fierce resistance and prepared extensive forces and equipment for the possibility.

A frequent mix-up is treating Downfall, Olympic, and Coronet as interchangeable names. Downfall was the overall invasion plan; Olympic was its proposed Kyushu phase; Coronet was the planned Honshu phase. Japan’s surrender eliminated the need for either landing.