In the years since the two atomic bombs were dropped on Japan, a number of historians have suggested that the weapons had a two-pronged objective. First, of course, was to bring the war with Japan to a speedy end and spare American lives.resident Harry S. Truman, warned by some of his advisers that any attempt to invade Japan would result in horrific American casualties, ordered that the new weapon be used to bring the war to a speedy end. On August 6, 1945, the American bomber Enola Gay dropped a five-ton bomb over the Japanese city of Hiroshima.