Nuclear fission the Manhattan Project during World War II (September 1, 1939 – September 2, 1945) carried out most of the early scientific work on fission chain reactions, culminating in the three events involving fission bombs that occurred during the war. The first fission bomb, codenamed "The Gadget", was detonated during the Trinity Test in the desert of New Mexico on July 16, 1945. Two other fission bombs, codenamed "Little Boy" and "Fat Man", were used in combat against the Japanese cities of Hiroshima and Nagasaki in on August 6 and 9, 1945 respectively. Even the first fission bombs were thousands of
Mark 5 nuclear bomb Mark 5 nuclear bomb The Mark 5 nuclear bomb and W5 nuclear warhead were a common core nuclear weapon design, designed in the early 1950s and which saw service from 1952 to 1963. The Mark 5 design was the first production American nuclear weapon which was significantly smaller than the 60 inch (150 cm) diameter implosion system of the Fat Man nuclear bomb design first used in 1945, down to 39 inches (99.1 cm) diameter. The Mark 5 design used a 92-point implosion system (see Nuclear weapon design) and a composite Uranium/Plutonium fissile material core or pit. The Mark 5