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 6 nuclear bomb US. Mark 18 bombs were eventually recycled into Mark 6 Mod 6 bombs after thermonuclear weapons were deployed in quantity. The Mark 18 was tested once in Operation Ivy King. Mark 6 nuclear bomb The Mark 6 nuclear bomb was an American nuclear bomb based on the earlier Mark 4 nuclear bomb and its predecessor, the Mark 3 Fat Man nuclear bomb design. The Mark 6 was in production from 1951 to 1955 and saw service until 1962. Seven variants and versions were produced, with a total production run of all models of 1100 bombs. The basic Mark 6 design