The base was built to support the island-hopping strategy used by allied nations fighting the Empire of Japan in the Pacific War.

The deep lagoon in the atoll offers excellent fleet anchorage for the largest ships.

In November 1942, the Empire of Japan built an airfield on Enewetak Atoll's Engebi Island, to refuel and support planes at Truk.

The action took place on three islands: Engebi, Parry, and Eniwetok by the US 22nd Marines and the Army's 106th Infantry.

In September 1944 Charles Lindbergh visited Engebi Airfield and United States Marine Corps flew the Corsairs.

By June 1944, the major projects on Engebi had been completed and Construction Battalion Maintenance Unit 594, CBMU 594, took over.

[5][6][7] US Navy Seabees with the 110th Naval Construction Battalion arrived at Eniwetok starting 21 February 1944.

Seabees built air facilities that included a major engine overhaul depot, and barracks for Army aviation personnel with quonset huts.

The Navy had stationed at base unit VB-109, VD-4, and VPB-109 flying Lockheed Ventura Harpoon-PV-1 and Consolidated PB4Y-2 Privateer.

[8] Seabees also built two (80-foot and 150-foot) coral-fill piers out into the lagoon on Eniwetok Island for unloading supplies.

In addition, Seabees built two berths that were used for ships to dock and do anti-aircraft target practice.

[10][11] Troops at sea on ships and boats need R&R, so in June 1945, the 67th Naval Construction Battalion arrived and built a 35,000-man recreation center on Parry Island.

[4][7] The local inhabitants, Micronesians, at Eniwetok were restricted to the smaller islands of Biijiri, Aomen, and the Rojoa complex.

Seabees of the 126th Battalion built a second fleet recreation center on Runit Island, codename Hawthorne, six weeks later it was crated up and shipped to Naval Base Ulithi.

[14][7] The deep lagoon the Navy set up fleet anchorage and a major US Naval Advance Base.

Service Squadron 10 started departing Enewetak Atoll on 4 October 1944 for Naval Base Ulithi arriving on the 15th.

[15] The US Navy set up a large ship and boat repair depot at Naval Base Eniwetok.

In September 944 a strong westerly storm hit Eniwetok, damaging many boats and barges and driving high-speed target rafts ashore.

Seaplanes did reconnaissance patrols and search, also rescue missions for downed aircrew men and survivors of sunk ships.

The most common seaplanes at the base were Consolidated PBY Catalina and Martin PBM Mariner.

[17] Some seaplane tenders at Naval Base Eniwetok: Hundreds of US Navy destroyers were used in the Pacific war.

The submarine attacked warships and sank supply ships that were needed by Japan to resupply their many bases in the Pacific.

US subs also did reconnaissance patrols, landed guerrilla special forces and search and rescue missions for downed aircrew men.

[24] US submarine had long ranges, but needed to be resupplied with fuel, food, torpedoes and deck gun shells.

While the submarine was being resupplied, and repaired if needed, crews could have a break (R&R) at the atoll's fleet recreation center.

[28][29][30] Naval Base Eniwetok was used for the Admiral Raymond A. Spruance's United States Fifth Fleet anchorage.

The USS Bowditch (AG-30) had surveyed the lagoon to find the best mooring for large and small ships.

[14] The United States Coast Guard built a LORAN (Long Range Navigational Signal) station at Eniwetok in January 1951.

[31][32] From 14 April 1948 through 18 August 1958, the United States conducted nuclear weapons testing at Eniwetok Atoll, exploding over 30 megatons.

From 1977 to 1980, the US constructed a concrete dome on Runit Island, under which radioactive soil and debris were deposited.