Nuclear weapons have changed war and defense more than any other weapon ever developed. The immense firepower of nuclear weapons, packed into small delivery packages, is an unprecedented change in the scale of destructiveness available for military use. Since the 1940s, all national security calculations must consider whether the adversary possesses or can obtain nuclear capability.
Operation Sandstone (US). This photo shows test X-Ray, a 37 kiloton atomic device. Enewetak Atoll in the Marshall Islands, 14 April 1948. The Mk 3 atomic bomb used for the Sandstone tests was 60 inches in diameter and weighed 10,500 lb. The explosive, core and firing system weighed 7,600 lb. The bomb was exploded from a 200 foot tower.
Today in WW II: 18 May 1944 Battle of Monte Cassino, Italy, ends with German evacuation of the site and occupation by Allied troops.
Atomic theory, based on Einstein's 1905 work on relativity and further developed by many other physicists, hinted that a nuclear energy bomb was possible. As World War II loomed in Europe and Asia, on 2 August 1939, Albert Einstein wrote to Pres. Roosevelt about the potential for a uniquely powerful uranium weapon and indications of German interest in it, the inspiration for the Manhattan Project. Still, nothing was done until 1942 when fear of nuclear development by Nazi Germany motivated action in the United States and England.
In June 1942, the U.S. War Department launched the top secret Manhattan Project to turn theory into actual weapons.
The nuclear weapons age began in 1945 with a successful atomic bomb test at the Trinity site in New Mexico, followed by U.S. use of two atomic bombs against Japanese cities, first Hiroshima then Nagasaki. These Olive-Drab.com pages present the history of nuclear weapons development and some information on the atomic and hydrogen bomb weapons fielded by the United States.
Operation Hardtack, Oak test (US). This photo shows the cloud from the explosion of the 8.9 megaton TX-46 hydrogen bomb (H-Bomb). The test device was 37 inches in diameter, 100.5 inches long, and weighed 6113 lb. The bomb was mounted on a barge in an area of 12 foot deep water, Enewetak Atoll in the Marshall Islands, 28 June 1958.
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