Atomic bombings of Hiroshima and Nagasaki


August 15, 2022

The atomic bombings of Hiroshima and Nagasaki, the last American strategic bombings in Japan, took place on August 6 and August 9, 1945 on the cities of Hiroshima (340,000 inhabitants) and Nagasaki (195,000 inhabitants). Hiroshima is the headquarters of the 5th Division of the Second General Army and the command center of General Shunroku Hata, and Nagasaki is chosen as the target rather than the historic city of Kyoto. Using a posteriori the pretext of the Japanese leaders' rejection of the conditions of the ultimatum of the Potsdam conference, the United States wishes to impose on Japan its unconditional surrender, the ousting of Emperor Hirohito and the adoption of a democratic political system. The American government also wishes, since these two new weapons are now operational (one was uranium, the other plutonium), to test them in full scale and show other countries, in particular the USSR, the decisive fire superiority they give to America, which makes this bombardment the inaugural act of the cold war. These bombings, which some consider to be one of the main war crimes of the Allies, remain the only use of nuclear weapons during a conflict. It was finally on August 14, following these bombardments, but also the Soviet invasion of Manchuria which had begun on August 8 and the surrender of the Japanese army in Guandong on August 10, that the Japanese government gave in and accept his surrender. Less than a month later, the signing of the acts of surrender of Japan on September 2, 1945 in Tokyo Bay put an end to the Second World War. The number of people killed by the explosion, the heat and the ensuing firestorm is difficult to determine and only estimates are available, ranging from 103,000 to 220,000 deaths, not counting subsequent cases of cancers (several hundred) or other side effects. The survivors of the explosions, the hibakusha, have become the symbol of a struggle against war and atomic weapons throughout the world. The impact of these bombardments raised fears of the subsequent use of atomic weapons in a nuclear war, an effect at the root of nuclear deterrence which largely weighed in the strategic choices of the Cold War.


A long-term project

Under the code name Manhattan Project, the secret program to research and build a nuclear weapon was launched in 1942, less than seven months after the United States entered the war, with the assistance of the United Kingdom and of Canada within the framework of the Quebec agreement signed in 1943, and the participation of many European scientists. The two bombs used against Japan (Little Boy with uranium and Fat Man with plutonium), are respectively the second and third to have been built, and they remain the only ones deployed since that date in a theater of operations. They are preceded by a first experimental bomb whose test took place under the code name Trinity in New Mexico in July 1945. In December 1944, the USAAF 509th Bomber Squadron was formed under the command of Colonel Paul Tibbets to drop these bombs once they were built; he was deployed to Tinian in May and June 1945. This squadron is equipped with B29 bombers from a special series, manufactured for atomic bombing, called "Silverplate", named after the USAAF's participation program in the Manhattan project. He trains using conventional bombs, but built to the template of atomic bombs, the “pumpkin bombs”. The two bombers who are going to drop their bomb on Hiroshima and Nagasaki, Enola Gay and Bockscar, belong to this special series.


Trinity is the name of the very first test of an atomic bomb in