On 24 August 1968, France conducted the ‘Canopus’ nuclear test, the country’s first multi-stage thermonuclear test, at Fangataufa atoll in the South Pacific Ocean. It was the fifth nation after the United States, the Soviet Union, the United Kingdom and China to cross the thermonuclear threshold.
‘Canopus’ was also France’s highest yielding test. With a 2.6 megaton yield, its explosive power was 200 times that of the Hiroshima bomb. The device weighed three tons and was suspended from a balloon at 520 meters. The fallout caused by this test contaminated large parts of Fangataufa atoll, leaving it off-limits for humans for six years, also affecting neighboring atolls.