During World War II, she carried President Franklin D. Roosevelt across the Atlantic to Mers El Kébir, Algeria, en route to a conference of vital importance in 1943 in Tehran with Prime Minister Winston Churchill of the United Kingdom and Joseph Stalin, leader of the Soviet Union.

When transferred to the Pacific Fleet in 1944, Iowa shelled beachheads at Kwajalein and Eniwetok in advance of Allied amphibious landings and screened aircraft carriers operating in the Marshall Islands.

Iowa was decommissioned for the last time in October 1990 after 19 total years of active service, and was initially stricken from the Naval Vessel Register (NVR) in 1995, before being reinstated from 1999 to 2006 to comply with federal laws that required retention and maintenance of two Iowa-class battleships.

[4] USS Iowa's main battery consisted of nine 16 in (406 mm)/50 caliber Mark 7 guns, which could fire 2,700 lb (1,200 kg) armor-piercing shells 20 nmi (23 mi; 37 km).

She got underway on 27 August for Argentia, Newfoundland, to counter the threat of the German battleship Tirpitz which was reportedly operating in Norwegian waters, before returning to the United States on 25 October for two weeks of maintenance at the Norfolk Navy Yard.

From 29 January to 3 February, she supported carrier air strikes made by Rear Admiral Frederick C. Sherman's Task Group 58.3 (TG 58.3)[11] against Kwajalein and Eniwetok atolls.

Iowa, in company with other ships, was detached from the support group on 16 February 1944 to conduct an anti-shipping sweep around Truk, with the objective of destroying enemy naval vessels escaping to the north.

On 18 March 1944, Iowa, flying the flag of Vice Admiral Willis A. Lee (Commander, Battleships, Pacific), joined in the bombardment of Mili Atoll in the Marshall Islands.

[4] In a last-ditch attempt to halt the United States campaign to recapture the Philippines, the Imperial Japanese Navy struck back with Shō-Gō 1, a three-pronged attack aimed at the destruction of American amphibious forces in Leyte Gulf.

In July, following the Bikini atomic experiments, the old battleship Nevada was selected as a target for a live fire exercise to be carried out by Iowa and other sea and air assets of the navy.

[18][19] In September 1948, as part of the post World War II drawdown of the armed forces, Iowa was deactivated at San Francisco, and then formally decommissioned into the United States Navy reserve fleets on 24 March 1949.

In the company of other naval vessels Iowa again engaged North Korean forces the following day, this time against enemy troop concentrations, supply areas, and suspected gun positions in and around Suwon Dan and Kojo.

The next day she entered Wonsan Harbor and shelled warehouses, observation posts and railroad marshaling yards before moving out to rejoin the UN flotilla aiding ground forces around Kosong.

[6] The following month, Iowa was part of the force involved in Operation Decoy, a feint to draw enemy troops into Kojo and bring them within striking distance of the battleships' big guns.

[6] In October 1952 Iowa was serving as flagship for the Commander, Seventh Fleet, and she engaged in 43 gun strikes on targets in the areas of Wonsan, Songjin, Kojo, Chaho, Toejo, Simpo, Hungnam and northern Inchon North Korea, and in 27 bombline operations.

[22] Iowa embarked midshipmen for at-sea training to Northern Europe in July 1953, and shortly afterwards took part in Operation Mariner, a major NATO exercise, serving as flagship of Vice Admiral Edmund T. Wooldridge, commander of the 2nd Fleet.

[27] From April to August 1984, Iowa underwent refresher training and naval gunfire support qualifications at Guantanamo Bay, Cuba and the Puerto Rican Operating area.

Other problems included hydraulic fluid leaks in all three main gun turrets, electrical wiring shorts, pump failures, deteriorated bilge piping, unrepaired soft patches on high-pressure steam lines, and frozen valves in the ship's firefighting system.

[32] On 25 April, Captain Larry Ray Seaquist assumed command of the battleship and her crew during Naval Gunfire Support requalification off Vieques Island near Puerto Rico.

[6] The presence of US naval vessels in the gulf was in response to a formal petition from Kuwait,[35] whose ships were being raided by Iranian forces who were attempting to cut off weapons shipments from the United States and Europe to Saddam Hussein's regime in Iraq, via Kuwaiti territory.

[6] On 20 February 1988, Iowa departed from the Persian Gulf, transited the Suez Canal, and set sail for the United States, arriving at Norfolk on 10 March for routine maintenance.

[38] Iowa continued with sea trials throughout August and September, then began refresher training in the waters around Florida and Puerto Rico in October, during which the ship passed an Operation Propulsion Program Evaluation.

[42][43] To support this claim, naval officials pointed to several different factors, including Hartwig's life insurance policy, which named Kendall Truitt as the sole beneficiary in the event of his death,[44] the presence of unexplained materials inside turret 2,[45] and his mental state, which was alleged to be unstable.

Spontaneous combustion was achieved with the powder, which had been originally milled in the 1930s and improperly stored in a barge at the Navy's Yorktown, Virginia, Naval Weapons Station during a 1988 dry-docking of Iowa.

[52] This revelation resulted in a shift in the Navy's position on the incident, and Admiral Frank Kelso, the Chief of Naval Operations at the time, publicly apologized to the Hartwig family, concluding that there was no real evidence to support the claim that he had intentionally killed the other sailors.

[55] New Jersey remained there until the Strom Thurmond National Defense Authorization Act of 1999 required the Secretary of the Navy to list and maintain Iowa and Wisconsin on the Naval Vessel Register.

The Act also required the Secretary of the Navy to strike New Jersey from the Naval Vessel Register and transfer the battleship to a not-for-profit entity in accordance with section 7306 of Title 10 of the United States Code.

[67] In late February the Port of Los Angeles (which includes the San Pedro area) rejected a proposal by the PBC to berth USS Iowa at its facilities because the battleship was not yet available.

[71][72] On 18 November 2010, the Port of Los Angeles Harbor Commissioners voted unanimously on a resolution to support Berth 87 as the future home of USS Iowa, clearing the way for The Pacific Battleship Center to send its completed application to the Navy.

After being anchored off the Southern California coast to have her hull scrubbed to remove any invasive species or contaminants, on 9 June 2012 she was permanently docked in San Pedro at Berth 87, along the Main Channel, directly south of the World Cruise Center.