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 36 nuclear bomb tamper-pusher which would undergo fission during the second stage fusion burn, doubling the weapon yield. Chuck Hansen wrote in Swords of Armageddon (1995) that Mark 36 nuclear bomb was produced in two yield versions, clean and dirty. He stated that clean version of Mark 36 had a yield of 6 megatons and that dirty version of Mark 36 had a design of maximum yield of 19 megatons. Mark 36 nuclear bomb The Mark 36 was a heavy high-yield United States nuclear bomb designed in the 1950s. It was a thermonuclear bomb, using a multi-stage fusion secondary system to generate yields