On August 6, 1945, during World War II (1939-45), an American B-29 bomber dropped the world’s first deployed atomic bomb over the Japanese city of Hiroshima. The explosion wiped out 90 per cent of the city and immediately killed 80,000 people; tens of thousands more would later die of radiation exposure. Three days later, a second B-29 dropped another A-bomb on Nagasaki, killing an estimated 129,000 people, most of whom were civilians.
Japan’s Emperor announced his country’s unconditional surrender in World War II in a radio address on August 15, just 6 days after the bombings citing the devastating power of “a new and most cruel bomb. These atomic bombings remain the only use of nuclear weapons in the history of warfare. At the time of its bombing, Hiroshima was a city of both industrial and military significance. A number of military units were located nearby, the most important of which was the headquarters of Field Marshal Shunroku Hata’s Second General Army, which commanded the defence of all of southern Japan, and was located in Hiroshima Castle.
People on the ground reported a brilliant flash of light followed by a loud booming sound. 30% of the population of Hiroshima were killed by the blast and resultant firestorm, and another 70,000 were injured. Perhaps as many as 20,000 Japanese military personnel were killed. U.S. surveys estimated that 4.7 square miles (12 km2) of the city were destroyed. Japanese officials determined that 69% of Hiroshima’s buildings were destroyed and another 6–7% damaged
On September 2, the Japanese government signed the instrument of surrender, effectively ending World War II. The ethical and legal justification for the bombings is still debated to this day.