The United States dropped an atomic bomb on the Japanese city of Hiroshima on August 6, 1945. The bomb, codenamed "Little Boy", was the first nuclear weapon ever used in warfare. It exploded with the force of 15,000 tons of TNT, instantly killing an estimated 70,000 people and leveling much of the city.
The bombing of Hiroshima was followed by the bombing of Nagasaki on August 9, 1945, which killed an estimated 40,000 people. These two bombings led to the surrender of Japan and the end of World War II.