Little Boy (nuclear weapon)
Little Boy was the code name for the first nuclear weapon used in warfare, which was dropped on the Japanese city of Hiroshima on August 6, 1945. While the military headquarters for Southern Japan, soon to be invaded if the Second World War continued, was near the center of the blast, the bomb caused extensive civilian casualties and damage to the city. There were at least 70,000 immediate fatalities, with long-term mortality of at least 100,000.
The weapon itself was a first-generation fission device, weighing 9,700 pounds, and having an explosive yield of between 15 and 18 kilotons of TNT equivalent. It used the gun-type rather than implosion technology, soon to be considered obsolete, and its fissionable material was 235 uranium.