Operation Crossroads was a pair of nuclear weapon tests conducted by the United States military at Bikini Atoll in July 1946. The purpose was to investigate the effect of nuclear weapons against warships. The test fleet was largely composed of obsolete and surplus US Navy ships, as well as three surrendered Axis ships. Test Able consisted of a Mark IIIbomb dropped from a B-29 Superfortress, while Test Baker consisted of a Mark III bomb detonated underwater. Some of the ships were sunk outright, many were damaged, and almost all were severely radioactively contaminated and had to be scuttled.
