Honshu was targeted by the planned Operation Coronet invasion in 1946.
Operation Coronet was the second phase of Operation Downfall, the proposed Allied invasion of Japan’s home islands. Planners intended to land on the Kanto Plain near Tokyo on Honshu in spring 1946. The first phase, Operation Olympic, was scheduled for November 1945 and would have attacked southern Kyushu.
Japan’s surrender canceled both operations before they began. The atomic bombings of Hiroshima and Nagasaki, the Soviet entry into the war against Japan, and Japan’s acceptance of surrender terms removed the need for an invasion. Coronet therefore remained a plan rather than a battle.
Honshu is Japan’s largest and most populous main island and contains Tokyo. Kyushu is the island associated with Operation Olympic, so the two planned operations are commonly mixed up. Coronet meant Honshu; Olympic meant Kyushu.