Atomic Bomb Dropped
In August 1945, near the end of the Second World War, the United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki. These were the first, and so far the only, uses of nuclear weapons in warfare. Within days Japan announced its willingness to surrender, ending the war and opening the nuclear age, whose dangers and moral questions still shape world politics.
The weapons grew out of the Manhattan Project, a vast secret American program, carried out with British and Canadian cooperation, begun after scientists warned that Nazi Germany might develop an atomic bomb. By 1945 Germany had surrendered, but fighting in the Pacific continued. Japanese forces had suffered heavy defeats, and American bombers had already devastated many Japanese cities with conventional and incendiary raids. Even so, Japan's leadership had not accepted unconditional surrender, and Allied planners expected an invasion of the home islands to be extremely costly. The first test of a nuclear device took place in New Mexico in July 1945. At the Potsdam Conference that month, the Allies issued a declaration demanding Japan's surrender.
On 6 August a B-29 bomber released a uranium bomb over Hiroshima, destroying much of the city in an instant. Three days later, on 9 August, a plutonium bomb was dropped on Nagasaki. Death tolls are uncertain and estimates vary, but historians generally agree that well over 100,000 people died by the end of 1945 from the blasts, fires and radiation sickness, the great majority of them civilians. Many survivors, known in Japan as hibakusha, suffered lasting illness and discrimination.
The Soviet Union declared war on Japan and invaded Manchuria between the two bombings, on 8 August. On 15 August Emperor Hirohito announced the surrender in a radio broadcast, and the formal ceremony took place aboard the USS Missouri in Tokyo Bay on 2 September.
Historians still debate what finally brought about the surrender. Some stress the shock of the atomic bombs, while others argue that the Soviet entry into the war was equally or more decisive, since it destroyed hopes of a negotiated peace through Moscow. The ethical question is also contested: supporters argue the bombings shortened the war and saved lives that an invasion would have cost, while critics contend they were unnecessary and that the targeting of cities was morally indefensible.
The legacy was profound. The bombings helped launch the Cold War arms race, and the logic of deterrence came to dominate international relations. Hiroshima and Nagasaki have since become global symbols of the human cost of nuclear weapons and the movement for disarmament.