Cold War: A Brief History
In July 1946, two atomic tests--code named "Operation Crossroads"--were conducted at Bikini Atoll in the Pacific. These tests explored the effects of airborne and underwater nuclear explosions on ships, equipment, and material. A fleet of 95 surplus and captured ships were used as targets, including the Saratoga, the Arkansas, and the Japanese battleship Nagato. These tests were witnessed by hundreds of reporters, politicians, and international observers, along with 42,000 military and scientific personnel. The two bombs used in Crossroads were identical in design and yield to the bomb used on Nagasaki.
The first test, ABLE, was dropped on July 1, from a B-29 and detonated over the target fleet. The bomb was exploded between 1,500 and 2,000 feet off target, perhaps due to a collapsed tail fin. The radioactivity created by the burst was minor, and within a day nearly all the ships could be reboarded.
The second test, BAKER, on July 25, was exploded underwater; it formed a 1/2-mile-wide column of water over a mile and a half into the sky. Serious contamination of the lagoon occurred. Bikini Island, some 3 miles from surface zero, could not be safely landed on until a week had passed. The blast sunk or capsized eight ships and severely damaged eight more.