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 4 nuclear bomb 4 had explosive yields of 1, 3.5, 8, 14, 21, 22, and 31 kilotons (4 to 130 TJ). A total of 550 Mark 4 nuclear weapons were produced. The Mark 4 was succeeded by the Mk6, which was generally similar but much improved. A variant called the W4 (Warhead 4), intended for use on the SM-62 Snark cruise missile, was designed but never built. The W4 design was cancelled in 1951. Mark 4 nuclear bomb The Mark 4 nuclear bomb was an American nuclear bomb design produced starting in 1949 and in use until 1953. The Mark 4 was based