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
B41 nuclear bomb B41 nuclear bomb The B-41 (also known as Mk-41) was a thermonuclear weapon deployed by the United States Strategic Air Command in the early 1960s. It was the most powerful nuclear bomb ever developed by the United States, with a maximum yield of 25 megatons. The B-41 was the only three-stage thermonuclear weapon fielded by the U.S. The development of the B-41 began in 1955 with a USAF requirement for a Class B (high-yield, over ) weapon. It was based on the "Fagotti (bassoon)" test device first fired in the Redwing Zuni test of 27 May 1956. An ICBM warhead