Operation Crossroads, a series of tests to determine the effects of atomic bombs on naval targets, began on 1 July 1946 at Bikini Atoll in the Pacific Ocean.
In the first test a B-29 Superfortress dropped a Nagasaki-type bomb from 30,000 feet centered on the battleship Nevada (BB 36) and other ships anchored in the lagoon. Although the bomb missed its intended target due to the wind, the ensuing detonation sank five vessels outright and heavily damaged nine other ships.
Test Baker, a shallow underwater burst on 25 July, sent water nearly 6,000 feet into the air, and sunk directly or indirectly 32 of the 83 ships of all types used in the experiment, including the carrier Saratoga (CV 3), which sunk in shallow water following 19 years of active service. The carrier Independence (CVL 22) was towed along with the other surviving target ships to Kwajalein Atoll for continuing decontamination in August and September. Some of the target ships were later towed back to the United States and Hawaii for radiological inspection; others were so lightly contaminated that they were remanned and sailed back to the United States by their crews. Many of the target ships were destroyed by sinking off Bikini Atoll, off Kwajalein Atoll, or near the Hawaiian Islands during 1946–1948. The support ships were decontaminated and radiologically cleared before returning to the fleet.
Operation Crossroads made clear the importance of atomic weapons for control of the sea. In addition, these tests provided much detailed data on the effects of atomic blasts and a sound technical basis for intensifying efforts to develop tactics and equipment whereby the damage of such attacks against naval task forces could be minimized.