Early on March 1, 1954, the United States exploded a hydrogen bomb, code-named Bravo, on the Pacific Ocean's Bikini Atoll, in the Marshall Islands.
It was the most powerful thermonuclear device ever tested by the U.S. -- 1,000 times larger than those dropped on Hiroshima and Nagasaki -- and exposed local islanders, 28 U.S. military weather observers and 23 Japanese fishermen who happened to be near the test site aboard a tuna trawler to near-fatal amounts of radiation.
Because of the power of the bomb, which was beyond even the expectations of its designers, as well as the resulting radioactive contamination of people and the environment, the Bravo blast triggered large-scale antinuclear movements in Japan and around the world, including the Russell-Einstein Manifest.