Operation Olympic

Operation Olympic was the planned invasion of southern Kyushu, scheduled to begin on November 1, 1945, as the opening phase of Downfall, a two-stage campaign to invade Japan. Its significance lay in the scale of the projected assault and the stark uncertainty surrounding its cost: senior military leaders offered widely different estimates even as Harry S. Truman approved the plan.

Strategic Setting

At a White House meeting on June 18, General Marshall presented a two-phase invasion plan. Olympic would target Kyushu, the southernmost of the Japanese islands, about 350 miles from Okinawa. Marshall judged the operation as difficult as the Normandy invasion but considered it the only course to pursue. In Truman’s diary, the choice was framed as whether to invade Japan proper or instead bomb and blockade it; yet the atomic bomb was not raised at the meeting reviewing the invasion plans, where discussion proceeded as though it did not exist.

Casualty Estimates and Stakes

The projected losses varied substantially. Marshall estimated that the first 30 days of Olympic would produce casualties comparable to those at Luzon, about 31,000. Admiral King considered Okinawa a more realistic comparison and estimated 41,000; Admiral Nimitz forecast 49,000 in the same period, 7,000 more than at Normandy. MacArthur’s staff put the figure at 50,000, though MacArthur himself, who supported the invasion, regarded that estimate as too high.

Other calculations encompassed a much broader campaign: an estimate covering invasions of both southern and northern Kyushu and then Japan proper put casualties at 220,000. A June 4 memorandum by General Thomas Handy, while listing advantages of making peace with Japan, said avoiding invasion could save 500,000 to one million lives. These figures show the immense human stakes being considered at the highest levels. Henry Stimson feared that Japanese soldiers and civilians would fight with unprecedented determination and that losses on both sides could exceed those of any other campaign in the war; he worried American dead and wounded might reach one million.

Downfall and Presidential Approval

Olympic was the first phase of Downfall, not the whole invasion plan. The second phase, Operation Coronet, would attack Honshu, Japan’s main island, in March 1946. Before that assault, the plan called for air bombardment to be intensified to an absolute maximum; one memorandum projected that more bombs would be dropped on Japan than had been used against Germany throughout the European war. Truman approved the plan. The account thus places Olympic within a projected sequence of invasion and intensified bombing, while making clear that the campaign’s anticipated cost remained uncertain and fiercely debated.