Operation Hailstone was a massive naval air and surface attack launched on February 17–18, 1944, during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

 by the United States Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 against the Japanese

Empire of Japan

The Empire of Japan is the name of the state of Japan that existed from the Meiji Restoration on 3 January 1868 to the enactment of the post-World War II Constitution of...

 naval and air base at Truk

Chuuk

Chuuk — formerly Truk, Ruk, Hogoleu, Torres, Ugulat, and Lugulus — is an island group in the south western part of the Pacific Ocean. It comprises one of the four states of the Federated States of Micronesia , along with Kosrae, Pohnpei, and Yap. Chuuk is the most populous of the FSM's...

 in the Caroline Islands

Caroline Islands

The Caroline Islands are a widely scattered archipelago of tiny islands in the western Pacific Ocean, to the north of New Guinea. Politically they are divided between the Federated States of Micronesia in the eastern part of the group, and Palau at the extreme western end...

, a pre-war Japanese territory.
Truk was a major Japanese logistical base as well as the operating "home" base for the Imperial Japanese Navy

Imperial Japanese Navy

The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...

's Combined Fleet

Combined Fleet

The was the main ocean-going component of the Imperial Japanese Navy. The Combined Fleet was not a standing force, but a temporary force formed for the duration of a conflict or major naval maneuvers from various units normally under separate commands in peacetime....

. Some have described it as the Japanese equivalent of the US Navy's Pearl Harbor

Pearl Harbor

Pearl Harbor, known to Hawaiians as Puuloa, is a lagoon harbor on the island of Oahu, Hawaii, west of Honolulu. Much of the harbor and surrounding lands is a United States Navy deep-water naval base. It is also the headquarters of the U.S. Pacific Fleet...

. The atoll

Atoll

An atoll is a coral island that encircles a lagoon partially or completely.- Usage :The word atoll comes from the Dhivehi word atholhu OED...

 was the only major Japanese airbase within range of the Marshall Islands

Marshall Islands

The Republic of the Marshall Islands , , is a Micronesian nation of atolls and islands in the middle of the Pacific Ocean, just west of the International Date Line and just north of the Equator. As of July 2011 the population was 67,182...

 and was a significant source of support for Japanese garrisons located on islands and atolls throughout the central and south Pacific.