The atomic bombings of Hiroshima and Nagasaki were nuclear attack near the end of World War II against the Empire of Japan by the United States at the executive order of U.S. President Harry S. Truman on August 6 and 9, 1945, respectively. After six months of intense fire-bombing of 67 other Japanese cities, followed by an ultimatum which was ignored by the Shōwa regime, the nuclear weapon "Little Boy" was dropped on the city of Hiroshima on Monday, page on Hiroshima casualties. August 6, 1945,Adams, S. & Crawford, A.. 2000. World War II. First edition. Printed in association with the Imperial War Museum. Eyewitness Books series. New York, Doring Kindersley Limited. followed on August 9 by the detonation of the "Fat Man" nuclear bomb over Nagasaki. These are to date the only attacks with nuclear weapons in the history of warfare.

The bombs killed as many as 140,000 people in Hiroshima and 80,000 in Nagasaki by the end of 1945, roughly half on the days of the bombings. Amongst these, 15 to 20% died from injuries or illness attributed to radiation poisoningHarry S. Truman Library & Museum. U. S. Strategic Bombing Survey: The Effects of the Atomic Bombings of Hiroshima and Nagasaki, June 19, 1946. President"s Secretary"s File, Truman Papers. 2. Hiroshima., page 22 of 51..Since then, more have died from leukemia (231 observed) and solid cancers (334 observed) attributed to exposure to radiation released by the bombs The somatic effects of exposure to atomic radiation: The Japanese experience, 1947–1997.In both cities, the overwhelming majority of the dead were civilians.Trinity and Beyond: The atomic bomb movie.Dir. Kuran, P., Nar. Shatner, W.. 1997. VHS. Goldhil Video, 1997.Six days after the detonation over Nagasaki, on August 15, Japan announced its surrender to the Allied Powers, signing the Instrument of Surrender on September 2, officially ending the Pacific War and therefore World War II.(Germany had signed its unavoidable Instrument of Surrender on May 7, ending the war in Europe.) The bombings led, in part, to post-war Japan adopting Three Non-Nuclear Principles, forbidding that nation from nuclear armament.



The Manhattan Project

The United States, with assistance from the United Kingdom and Canada in their respective secret projects Tube Alloys and Chalk River Laboratories, designed and built the first atomic bombs under what was called the Manhattan Project. The scientific research was directed by American physicist J. Robert Oppenheimer. The Hiroshima bomb, a gun-type bomb called "Little Boy", was made with uranium-235, a rare isotope of uranium. The atomic bomb was first tested at Trinity Site, on July 16, 1945, near Alamogordo, New Mexico. The test weapon, "the gadget," and the Nagasaki bomb, "Fat Man", were both implosion-type devices made primarily of plutonium-239, a synthetic element.

Choice of targets