Commissioned on 19 September 1942, Thurston was converted into an auxiliary transport by the Atlantic Basin Iron Works of Brooklyn, New York, and was ready for sea on the 24th.

Following shakedown training out of Little Creek, Virginia, and landing exercises with Army units at Solomons Island, Maryland, the transport sortied on 24 October with Task Group (TG) 34.9, the Center Attack Force, for the invasion of North Africa.

In early June, Thurston embarked units of the 16th Infantry Regiment and headed to Algiers for landing rehearsals.

The convoy arrived off Algiers on 6 November and, that evening, was subjected to an air attack in which destroyer USS Beatty (DD-640), SS Santa Elena, and the Dutch ship SS Mornix van St. Aldegonde were torpedoed and sunk while Allied ships splashed six German planes.

After a week at Gourock, the transport got underway for the United States on the last day of November and reached New York on 9 December 1943.

Thurston carried troops from New York to Liverpool in January 1944; to Gourock in February; and to Cardiff, Wales, in April.

When the ship finished unloading at Cardiff on 4 April, she proceeded to Loch Long for three weeks of landing exercises to prepare for Operation Overlord, the invasion of Hitler's "Fortress Europe."

She anchored at Portland, England, on the 29th and sustained minor damage there on 28 May when a German bomb exploded 30 yards off her port side.

She reached Pearl Harbor on the 22nd; debarked the passengers; embarked garrison troops; and proceeded via Eniwetok to the Marianas.

Thurston called at Tulagi on the 12th and continued to Espiritu Santo to load elements of the Army's 27th Infantry Division.

The ship debarked her troops at the Hagushi Beaches on 9 April and, five days later, headed for the Marianas, whence she was routed, via Ulithi and Manus, to New Caledonia.

She arrived at Manila on 8 July, discharged her troops and cargo there, moved to Tacloban, and embarked homeward-bound naval personnel.

The transport called at Ulithi to pick up more sailors and, as the war ended, anchored at San Francisco on 14 August.

Thurston was decommissioned and returned to the War Shipping Administration on 1 August 1946 and resumed the name Del Santos.

She remained in merchant service as Chickasaw until 7 February 1962 when she ran aground on Santa Rosa Island off the coast of California.