Returning to duty in 1942, she saw service in the Pacific War, first supporting the rest of the fleet at the Battle of Midway, and then patrolling the Fiji Islands to guard against Japanese incursion.

She was sailing back to the Pacific Theater when word was received that the war had ended, so she turned around and returned to the Port of Long Beach, CA.

[2][3] She was armed with a main battery of eight 16 in /45 caliber Mark 1 guns in four twin-gun turrets on the centerline,[a] two forward and two aft in superfiring pairs.

The secondary battery consisted of sixteen 5-inch (127 mm)/51 caliber guns, mounted individually in casemates clustered in the superstructure amidships.

She appeared at Annapolis, Maryland, for the 1922 United States Naval Academy graduation and at Boston, Massachusetts, for the anniversary of the battle of Bunker Hill and the Fourth of July.

[7] From 18 August to 25 September, she paid her first visit to a foreign port transporting Secretary of State Charles Evans Hughes to Rio de Janeiro for Brazil's Centennial Exposition.

As the first Japanese aircraft appeared and explosions rocked the outboard battleships, Maryland's bugler blew general quarters.

[6] Seaman Leslie Short—addressing Christmas cards near his machine gun—brought the first of his ship's guns into play, shooting down one of two torpedo bombers that had just released against Oklahoma.

Inboard of Oklahoma, and thus protected from the initial torpedo attack, Maryland managed to bring all her antiaircraft (AA) batteries into action.

[4] The devastating initial attack sank Oklahoma, and she capsized quickly, with many of her surviving men climbing aboard Maryland to assist her with anti-aircraft defenses.

[9] Maryland continued to fire and, after the attack, sent firefighting parties to assist her compatriots, especially attempting to rescue survivors from the capsized Oklahoma.

[6] The Japanese erroneously announced that Maryland had been sunk, but on 30 December, the damaged ship entered Puget Sound Navy Yard for repairs just behind Tennessee.

Like the other older battleships, she was not fast enough to accompany the aircraft carriers, so she operated with a backup fleet protecting the West Coast.

She then moved to Espiritu Santo to guard against Japanese incursion, but heat and heavy rains plagued this tour of duty.

During a five-week overhaul at Pearl Harbor's shipyard, several 40 millimetres (1.6 in) AA guns were installed on the top decks and foremast as protection against anticipated Japanese air raids in future operations.

Maryland returned to Efate Island staging area, where she joined a large task force preparing for an assault on Tarawa.

In her first offensive action of the war, Maryland's guns opened fire at 05:00, destroying a shore battery with five salvos on the southwestern point of Betio Island in the Tarawa Atoll.

[12] Maryland steamed from San Pedro, California on 13 January 1944, and rendezvoused with Task Force 53 at Lahaina Roads for two days of loading ammunition, refueling, and provisioning ahead of a new operation supporting the Marshall Islands campaign.

She became the flagship for Admiral Connally for the next two weeks, resupplying and refueling many of the smaller ships in the operation until she departed with a task unit of carriers and destroyers on 15 February 1944, steaming for Bremerton Navy Yard, where she underwent another overhaul, with her guns being replaced.

The attack caused light casualties, and in 15 minutes she was underway for Eniwetok, and from there she steamed for the repair yards at Pearl Harbor (in reverse the whole time so as not to do further damage to her bow[13]),[4] escorted by two destroyers.

[11] Four days later, organized resistance collapsed, permitting the fire support ships to retire to the Admiralty Islands at the end of the month.

The fleet sortied 12 October, and Maryland joined Task Group 77.2, which was the gunfire and covering force for the invasion of Leyte.

[14] On 24 October, Maryland, West Virginia, Mississippi, Tennessee, California, and Pennsylvania sailed to the southern end of Leyte Gulf to protect Surigao Strait with several cruisers, destroyers, and PT Boats.

1 and 2, pierced the forecastle, main, and armored decks, and blew a hole in the 4-inch steel, causing extensive damage and starting fires.

There she joined the 5th Fleet and Rear Admiral Morton Deyo's Task Force 54 (TF 54), which was preparing for the invasion of Okinawa.

[11] Japanese forces responded with several air raids, with two of Maryland's radar picket destroyers being struck by kamikaze planes, with Luce sinking.

On 3 April, she was moved to the west coast invasion beaches to assist the cruiser Minneapolis in destroying several shore batteries.

[14] Maryland continued fire support duty until 7 April, when she steamed north to intercept a Japanese surface force with TF 54.

They steamed via the Mariana Islands and Guam to Pearl Harbor,[4] and she reached the Puget Sound Navy Yard at Bremerton on 7 May for repairs and an extensive refit.

[15] During the remaining months of 1945, Maryland made five voyages between the west coast and Pearl Harbor, returning more than 8,000 servicemen to the United States.