On July 16, 1945, the United States conducted history’s first test of a nuclear device (code-named Trinity) in the desert scrubland of south-central New Mexico. Weeks later, on August 6 and 9, it became the first—and thus far only—nation to use nuclear weapons operationally, on the Japanese cities of Hiroshima and Nagasaki, respectively. Whether “the bomb” alone ended World War II remains in debate, but its success indisputably left other powers coveting nukes of their own.

Testing ramped up through the 1940s and ’50s, most visibly in the Pacific Ocean, initially as American physicists and military personnel sought to understand the capabilities of their superweapon and how to develop it as a deterrent to future wars. The latter goal took on new meaning on Aug. 29, 1949, when the Soviet Union tested its first nuclear device, followed by Britain on Oct. 3, 1952, and France on Feb. 13, 1960.

Testing in the Pacific included American tests mainly in the Marshall Islands (notably Bikini Atoll), British tests off Australia and in the Gilbert and Ellice islands (present-day Kiribati and Tuvalu), and French tests in Polynesia. The October 1962 Cuban Missile Crisis, which brought the United States and Soviet Union to the brink of nuclear war, sobered them and Britain the following year into signing the Partial Nuclear Test Ban Treaty, which prohibited all but underground testing. That ended most tests in the Pacific, though resident islanders still suffer health problems from the effects of radioactive contamination. MH

  • American soldiers in the Marshalls observe one of 35 thermonuclear detonations conducted between April and August 1958 during Operation Hardtack / Getty Images
  • France gets into the act with a nuclear test at Mururoa Atoll in French Polynesia on Aug. 6, 1970. / Getty Images
  • Americans on Japtan Island in Enewetak observe Mohawk, one of 17 atmospheric nuclear tests conducted between May and July 1956 during Operation Redwing / National Archives
  • A 34-kiloton French device code-named Dioné detonates at Mururoa on June 5, 1971. / Getty Images
  • Operation Ivy, the first tests of a hydrogen bomb, kicks off with Mike, the first oftwo detonations on Enewetak Atoll, on Nov. 1, 1952. / Getty Images
  • Members of the press and crewmen aboard the frigate HMS Alert, all wearing protective “goon suits,” await Britain’s second test of a hydrogen bomb from 35 miles off Malden Island, Kiribati, on May 31, 1957 / Getty Images
  • This is the view of the Baker test from a tower on Bikini some 3.5 miles away. The atoll hosted 23 tests in all and made headlines, prompting its adoption as a name for the iconic two-piece women’s bathing suit. / U.S. Navy
  • U.S. Navy personnel examine the damage inflicted on the heavy cruiser USS Pensacola after the July 1946 Bikini tests. / US Navy

This article appeared in the July 2020 issue of Military History magazine. For more stories, subscribe here and visit us on Facebook: