Planned Invasion of Japan


Olympic & Coronet



By the middle of 1945, it became evident that Japan's demise was near. One strike and Japan would be blown off the map. The U.S. felt that the only way to do this was by directly invading Japan through the islands of Kyushu and Honshu. This planned invasion of Japan was known as Operation Downfall. American military commanders Douglas MacArthur, Chester Nimitz, Ernest King, William Leahy, Hap Arnold, and George Marshall were given control of planning the operation. The invasion plans were drawn up in April 1945 by the Combined Chiefs of Staff at the Argonaut Conference.

Geographically, Kyushu was located in southern Japan, Honshu in the north. This is depicted in the map below.

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The operation consisted of two sub-operations - Operation Olympic and Operation Coronet. Chronologically, Operation Olympic would come first. It was to take place in southern Kyushu, one of the only places in Japan that could sport a large amphibious landing. Set to begin on November 1, 1945, the operation entailed appropriating three beaches - Miyazaki, Ariake, and Kushikino.


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Pictured above is a map of where the invasions would take place in Kyushu.

The goal of the U.S. was to base naval support craft and establish 40 air groups. These airbases would later aid in Operation Coronet. The success of Operation Olympic was vital and had to be accomplished at all costs. With this in mind, military figures were even prepared to combat the Japanese with poisonous gases.

Operation Coronet was essentially a continuation of Olympic. Originally, the invasion was supposed to start on December 1, 1945, but the date was later postponed to March 1946. During this operation, the U.S. would have received support from veterans of Europe and South-East Asia. Britain was to supply twelve aircraft carriers and several battleships. These ships would be coupled with air support from planes captured in Kyushu.

President Truman
President Truman

Despite the tremendous preparation put it into executing the plan, President Truman did not follow through and authorized the use of an atomic bomb. Truman's advisors warned him about the severe casualties that would be accumulated. It was estimated that there would be well over a million casualties. The Japanese would defend with extreme tenacity.