World War II: Operation Hailstone begins: U.S. naval air, surface, and submarine attack against Truk Lagoon, Japan's main base in the central Pacific, in support of the Eniwetok invasion.

Operation Hailstone was a large-scale United States Navy air and surface attack on Truk Lagoon on 17–18 February 1944, conducted as part of the American offensive drive against the Imperial Japanese Navy in the Pacific Ocean theatre of World War II.

Chuuk Lagoon, previously Truk Atoll, is an atoll in the central Pacific Ocean. It lies about 1,800 kilometres northeast of New Guinea and is part of Chuuk State within the Federated States of Micronesia (FSM). A protective reef, 225 kilometres (140 mi) around, encloses a natural harbour 79 by 50 km, with an area of 2,130 km² (820 sq mi). It has a land area of 93.07 square kilometres, with a population of 36,158 people and a maximal elevation of 443 metres (1,453 ft). Weno city on Weno Island functions as both the atoll's capital and the state capital, and is the largest city in the FSM with its 13,700 people.

The Battle of Eniwetok was a battle of the Pacific campaign of World War II, fought from 17 to 23 February 1944 on Enewetak Atoll in the Marshall Islands. The invasion of Eniwetok followed the American success in the Battle of Kwajalein to the southeast. Capture of Eniwetok would provide an airfield and harbor to support attacks on the Mariana Islands to the northwest. The operation was officially known as "Operation Catchpole" and was a three-phase operation involving the invasion of the three main islands in the Enewetak Atoll.