She was built under a Maritime Commission contract (MC hull 1101) at Vancouver, Washington, and was laid down by the Kaiser Shipbuilding Co. on February 1, 1943 as Didrickson Bay (ACV-64). Renamed Tripoli on 3 April 1943 and launched on 13 July 1943, sponsored by Mrs. Leland D. Webb, and commissioned on October 31, 1943, at Astoria, Oregon, Capt. Wendell G. Switzer in command.
Following shakedown training off the California coast, the escort carrier entered the repair base at San Diego, California. There, on January 4, 1944, gasoline was inadvertently dumped into the water around the forward part of the ship, on the starboard side. Acetylene torch sparks ignited the volatile mixture, and flames quickly spread from the bow to frame 82, engulfing the forward galley walkway and the island superstructure. Yardcraft and the ship's crew battled the flames and soon had the fire under control, but not before two men had died.
After providing air cover for a convoy routed to the British West Indies, Tripoli's Wildcats and Avengers searched the sea lanes northwest, southwest, and west of the Cape Verdes before putting into Recife, Brazil, on 5 April to refuel and provision. Back at sea again two days later, Tripoli continued the routine of daily launchings and recoveries of her aircraft, guarding the Allied sea lanes against the incursions of enemy U-boats.
About one hour before sunrise on 19 April, one of Tripoli's Avengers made radar contact with a German U-boat as the submarine cruised on the surface awaiting the arrival of her "Milch Cow" or refuelling partner. The enemy, U-513, put up a spirited anti-aircraft barrage while the Avenger made three attacks. A pattern of rockets bracketed the submarine on the first pass as the Germans prepared to dive for comparative safety. On the second run, the aircraft's depth charges failed to release, giving the enemy submersible the time she needed to dive. The U-boat evaded the aircraft's last attack - a mine - but also missed her fuelling rendezvous with "Milch Cow" U-488.
Returning to Norfolk on 29 April, Tripoli underwent voyage repairs before embarking Composite Squadron six 12 Avengers and nine FM-2 Wildcats. She then formed up with CortDiv 7 and departed Hampton Roads on 24 May for further searches in the vicinity of the Cape Verdes. Four days out, she changed course to intercept a German submarine estimated to be proceeding southwest from a position west of the Madeira Islands. When no contact was made by 30 May, Tripoli and her consorts steamed north to rendezvous with a convoy bound for Nova Scotia.
Following her return to Norfolk on 18 June, Tripoli spent two months in carrier qualification training off Quonset Point, Rhode Island, before making port again at Norfolk on 15 July. Embarking Composite Squadron 6, she conducted two weeks of pilot qualifications in the Chesapeake Bay area before departing Hampton Roads on 1 August, bound for her new base of operations, Recife.
Screened by and , the escort carrier proceeded south until 1 August, when O'Toole developed a sonar contact and gave chase. Aircraft from Tripoli laid patterns of sonobuoys at the initial contact point and dropped smoke floats and float lights on an oil slick. Picking up the "scent", O'Toole straddled the floats with her "Hedgehog" projectiles and depth charges and soon radioed victoriously "We hit the rodent!" A brief visual examination of the evidence - debris and a large quantity of diesel oil - satisfied the hunter-killer group that they had indeed sunk an enemy submarine. However, a post-war examination of German records did not confirm the kill. As night fell, Tripoli vectored two aircraft to another sonar contact by O'Toole, and four depth bombs were dropped - keeping another U-boat down and running.
Tripoli and her group then returned to Recife on 13 August and reported for duty with Admiral Jonas H. Ingram's 4th Fleet. Designated as the center of TG 47.7, the escort carrier put to sea on 22 August with the four destroyer escorts of CortDiv 24 to operate against a homeward-bound German submarine estimated to pass at 25° south latitude and 5° west longitude.
After a fruitless search pursuing two fading sonar contacts in the mid-South Atlantic narrows, Tripoli and her group returned to Recife on 11 September for provisioning and fuelling. Underway again two days later, TG 47.7 headed out to conduct another search - this time along the estimated track of two U-boats slated to rendezvous for refuelling. One of the target U-boats was U-1062, a "Milch Cow" bound from Penang, Malaya, with a cargo of valuable petroleum products for the German war effort. Ordered to fuel U-219, outward-bound for the Far East, U-1062 prepared to rendezvous with her smaller sister boat in the South Atlantic narrows - directly in the path of the Tripoli escort group.
Passing to the westward of the Cape Verdes, TG 47.7 made rendezvous with the 's escort group to conduct a joint hunter-killer operation against the two enemy boats. Round-the-clock searches by radar-equipped Avengers continued until 40 minutes after sunset on 28 September, when a TBF piloted by Lt. William R. Gillespie, USNR, reported a definite contact with the surfaced U-219 only 11 miles from the enemy's estimated track.
Gillespie went in to conduct a low-level rocket attack, but was shot down by heavy flak. Another Avenger, drawn to the battle, braved the flak to conduct another rocket run and also dropped depth bombs, while a Wildcat strafed the U-boat which struggled desperately to dodge the harassing attacks by the American aircraft.
U-219 emerged from the firefight unscathed; but U-1062 did not enjoy similar good fortune. , one of Mission Bay's screen, homed in on sonobuoy indications on 30 September and sank the "Milch Cow" with a four-charge pattern. In the meantime, U-219 was not yet home free - one of Tripoli's Avengers dropped depth bombs on the fleeing boat on 2 October. American sonar-men felt that they had definitely "killed" the U-boat, but post-war accounting showed that U-219 had escaped to Batavia, Java.
When fuel supplies ran low, Tripoli returned to Recife on 12 October. She conducted one further search of the narrows from 26 October to 12 November before heading for a much-needed overhaul at Norfolk. Subsequently, the escort carrier sailed for the Pacific and, after transiting the Panama Canal and touching at San Diego, arrived at Pearl Harbor on 10 January 1945.
Arriving at San Diego on 29 August with 500 Navy veterans, Tripoli returned to Pearl Harbor on 8 September before resuming local operations - including night carrier qualifications - through November. She subsequently made one trip with Army passengers to San Pedro, California, and a further "Magic Carpet" run to San Diego. The carrier departed the west coast on 15 January 1946 for deactivation overhaul at Norfolk. On 22 May 1946, the need for her services required, Tripoli was decommissioned and laid up in reserve.
Over the next six years, Tripoli conducted 44 transport voyages, mostly to European and Mediterranean ports, but with one visit to Hawaii and two to the Far East. Following the ship's third voyage to Europe, Tripoli was berthed at the Port Newark Terminal on 5 August 1952 where she loaded 45 Republic F-84 Thunderjet aircraft, 90 wingtip fuel tanks, and related gear for transport to the Far East. After going to sea on 7 August, bound for Japan, Tripoli steamed via the Panama Canal and San Diego and made port at Yokosuka with her vital cargo on 5 September, where cranes lifted the reinforcements ashore - soon to be in action in their ground-attack role in Korea. After loading battle-damaged aircraft for repairs in the United States, the carrier embarked 245 Navy and Marine Corps personnel for rotation back to Alameda Naval Air Station, California Making port on the West Coast on 22 September, she then put to sea for the Far East a second time, once again carrying jet aircraft to Yokosuka, as well as transporting men of the Sea Echelon of Boat Unit 1. Loading a cargo of helicopters and military passengers, Tripoli returned to the west coast and arrived at Alameda on 11 November 1952. Subsequently making her sole Hawaiian voyage under MSTS, Tripoli then headed east to finish her career with transport voyages to European and Mediterranean ports.
Receiving "smart ship" awards from MSTS in the intervening years, Tripoli was reclassified a utility carrier and redesignated CVU-64 on 12 June 1955. Again redesignated T-CVU-64 on 1 July 1958, Tripoli was decommissioned at New Orleans, La., on 25 November 1958 and subsequently struck from the Navy List on 1 February 1959. Her hulk was then scrapped by a Japanese firm in January 1960.