SECTION 6 THE ATOMIC BOMBING AND U.S. OCCUPATION OF HIROSHIMA AND NAGASAKI Having tested Project TRINITY in New Mexico on 16 July 1945, the United States had two atomic bombs ready for use in early August 1945. They were both dropped on Japan, the first over Hiroshima on 6 August 1945 and the second over Nagasaki on 9 August. The Hiroshima weapon was smaller, with a yield of about 15 kilotons compared to the 21 kilotons for the Nagasaki detonation. As planned, they both were air bursts, the first at about 1,900 and the second at 1,650 feet above the city. The burst height was the key factor in preventing any significant residual contamination. Vivid descriptions of the detonations appear in a number of sources, including John Hersey’s Hiroshima (1946) and Takashi Nagai’s We of Nagasaki (1951): t e A tremendous flash of light cut across the sky. . . . It seemed a sheet of sun (Hersey, p. 8). e The red was bright enough to stun a person, but the blue! -- it was so bright that not even the worst liar could have found the words to express it (Nagai, p. 31). e It was getting dark and cold very fast. I thought an airplane must have crashed into the sun (Nagai, p. 23). The objective of the bombings was to bring World War II to a quick end, thereby avoiding the death and destruction that would inevitably result from the planned invasion of the Japanese home islands. During the U.S. invasion of Okinawa, 1 April 1945 through 21 June 1945, the U.S. casualties included about 12,000 killed, and the Japanese losses approached 100,000 killed. On 26 July 1945, President Harry Truman urged the Japanese to surrender unconditionally or face “prompt and utter destruction." The Japanese ignored the warnings, having heard similar predictions before fire raids. Subsequently, they experienced the loss of more than 75,000 people in Hiroshima and more than 35,000 in Nagasaki. Allied forces. On 2 September 1945, Japan officially surrendered to The early radiation surveys and the American occupation of Hiroshima and Nagasaki followed shortly thereafter. 153