Operation Grapple with the American Manhattan Project in August 1943. Many of Britain's top scientists participated in the British contribution to the Manhattan Project. After the war, fearing that Britain would lose its great power status, the British government resumed the atomic bomb development effort, now codenamed High Explosive Research. The successful test of an atomic bomb in Operation Hurricane in October 1952 represented an extraordinary scientific and technological achievement, but Britain was still several years behind the United States in nuclear weapons technology. In July 1954, the Cabinet decided to develop the hydrogen bomb. The United Kingdom Atomic Energy Authority Atomic
Operation Upshot–Knothole Operation Upshot–Knothole Operation Upshot–Knothole was a series of eleven nuclear test shots conducted in 1953 at the Nevada Test Site. It followed "Operation Ivy" and preceded "Operation Castle". Over 21,000 soldiers took part in the ground exercise Desert Rock V in conjunction with the "Grable" shot. "Grable" was a 280mm shell fired from the "Atomic Cannon" and was viewed by a number of high-ranking military officials. The test series was notable as containing the first time an atomic artillery shell was fired (shot "Grable"), the first two shots (both fizzles) by University of California Radiation Laboratory—Livermore (now Lawrence Livermore National