See main article: Casablanca-class escort carrier. Admiralty Islands was a Casablanca-class escort carrier, the most numerous type of aircraft carriers ever built, and designed specifically to be mass-produced using prefabricated sections, in order to replace heavy early war losses. Standardized with her sister ships, she was 512inchesft3inchesin (ftin) long overall, she had a beam of, at her widest point, this was, and a draft of 20inchesft9inchesin (ftin). She displaced standard, with a full load. She had a 257feet long hangar deck and a 477feet long flight deck. She was powered with two Skinner Unaflow reciprocating steam engines, which drove two shafts, providing 9000shp, thus enabling her to make . The ship had a cruising range of 10240nmi at a speed of . Her compact size necessitated the installment of an aircraft catapult at her bow, and there were two aircraft elevators to facilitate movement of aircraft between the flight and hangar deck: one each fore and aft.
One 5inches/38 caliber dual-purpose gun was mounted on the stern. Anti-aircraft defense was provided by eight Bofors 40mm anti-aircraft guns in single mounts, as well as 12 Oerlikon 20sp=usNaNsp=us cannons, which were mounted around the perimeter of the deck. By the end of the war, Casablanca-class carriers had been modified to carry thirty 20 mm cannons, and the amount of 40 mm guns had been doubled to sixteen, by putting them into twin mounts. These modifications were in response to increasing casualties due to kamikaze attacks. Although Casablanca-class escort carriers were designed to function with a crew of 860 and an embarked squadron of 50 to 56, the exigencies of wartime often necessitated the inflation of the crew count. Casablanca-class escort carriers were designed to carry 27 aircraft, but the hangar deck could accommodate more. Because Admiralty Islands only operated in a replenishment capability, she usually operated with about 60 aircraft on board, the maximum carrying capacity at which take-offs would still be possible.
Her construction was awarded to Kaiser Shipbuilding Company, Vancouver, Washington under a Maritime Commission contract, on 18 June 1942, under the name Chaplin Bay, as part of a tradition which named escort carriers after bays or sounds in Alaska. She was renamed Admiralty Islands on 26 April 1944, as part of a new naval policy which named subsequent Casablanca-class carriers after naval or land engagements. As the ninety-ninth escort carrier, and the forty-fifth of the Casablanca class carriers, she received the hull symbol CVE-99. The escort carrier was laid down on 26 February 1944, MC hull 1136, the forty-fourth of a series of fifty Casablanca-class escort carriers. She was launched on 10 May 1944; sponsored by the wife of Vice Admiral Homer N. Wallin; transferred to the United States Navy and commissioned on 13 June 1944.
Upon being commissioned, Admiralty Islands got underway, on 2 July 1944, from Astoria, Oregon on a shakedown cruise down the West Coast to San Francisco. Upon arriving, she took on fuel oil and aviation gas. Proceeding southwards, she arrived at San Diego on 14 July, for additional training. There, she was assigned to join the Carrier Transport Squadron of the Pacific Fleet, ferrying aircraft, personnel, and supplies to the frontline in the West Pacific. She took on a load of cargo at San Diego, and departed westwards.
Transiting via Pearl Harbor, Admiralty Islands headed to Majuro, in the Marshall Islands, arriving there on 9 August, where she disembarked her cargo. She returned to Pearl Harbor, where she transported aircraft and personnel back to the West Coast, arriving at San Francisco on 24 August. She then made another round-trip transport run in September, this time to Finschhafen, New Guinea. She returned to San Diego on 7 October, where she underwent refit from 8 October to 26 October. On 29 October, she left port, headed northwards towards Alameda, where she loaded aircraft and passengers from Naval Air Station Alameda. She then commenced another trip to Finschhafen, arriving on 21 November. Upon disembarking her load, she proceed to Manus Island in the Admiralty Islands, docking in Seeadler Harbor on 23 November. On her way back, she stopped at Pearl Harbor from 6 to 7 December, before reaching San Diego a week later. There, she loaded more aircraft and military passengers, and sailed westwards, touching Pearl Harbor on 24 December. On 26 December, the day after Christmas, she left port, bound for Guam.
Upon reaching Guam on 6 January 1945, Admiralty Islands conducted training operations for two days, before sailing for Hawaii on 10 January. She reached Pearl Harbor on 20 January, where repairs were made to her main engine, finishing on 31 January. Upon the completion of repairs, she was assigned to become a replenishment carrier as a part of Task Group 50.8.4, the mobile replenishment group supporting the frontline Fifth Fleet. Replenishment carriers enabled larger fleet carriers to operate out at sea for extended periods of time without having to withdraw to port. She served alongside three other escort carriers,,, and . She took on a complement of sixty-one replacement planes at Pearl Harbor, and she left port on 2 February, bound for the waters off of Iwo Jima, in support of the planned landings there. After stopping at Eniwetok and Ulithi, she began replenishment operations on 16 February, continuing throughout the next five months.
On 2 March, the carrier returned to Guam for provisioning and minor repairs. On 13 March, she sortied, this time in support of the prolonged Battle of Okinawa. This time, her task group had the task of resupplying both the escort carriers and the fleet carriers of the Fast Carrier Task Force. Throughout this period, she received provisions and aircraft from Guam, making trips to and from the island. On 18 April, Admiralty Islands suffered an operational casualty from a Grumman F6F Hellcat fighter crashing into her flight deck. At 12:17, she sounded flight quarters, and she commenced launching replacement aircraft at 13:52, delivering one Grumman F6F Hellcat, two Grumman TBM Avengers, and two Curtiss SB2C Helldivers to the fleet carrier . At 14:06, she began recovering ten combat-fatigued aircraft (commonly known as "Flyable Duds") from Essex.
The first aircraft which attempted to land was a Hellcat, piloted by Ensign Roy Edward Jones. As it approached Admiralty Islands, the pilot received a signal to abort its landing, after it responded poorly to "low" and "opposite slant" flag signals. With the "wave off" signal from the Landing Signal Officer (LSO) being sent late, the aircraft continued to lose altitude. As the pilot applied full throttle, its tail hook caught the No 5. arresting wire, forcing the aircraft onto a gun mount, splitting the fighter in half. The cockpit and engine were ejected into the ocean, whilst the latter half dangled off the wire. The carrier's crew was unable to retrieve the front half of the fighter, nor the body of the pilot. The LSO was forced to jump into the safety net, breaking his leg.
Admiralty Islands returned to Guam on 24 April for repairs to her boilers, two of which had become dysfunctional. Whilst she was moored for repairs, the other three escort carriers of her task group endured Typhoon Connie, which transited northwards through the waters east of Okinawa. Upon the completion of repairs, she departed on 14 May to continue replenishment duties. She continued these duties throughout May, before being detached and transiting, via Guam, to Saipan on 15 June. She remained in port for two weeks, before being assigned to Task Group 30.8, the Fleet Oiler and Transport Group which was supporting the Third Fleet, which was conducting airstrikes against the Japanese mainland. She suffered another casualty on 20 July, when aircraft from one of the fleet carriers conducting strikes was diverted to Admiralty Islands because its home carrier had experienced a crash landing, with a resulting fire. All of the aircraft landed safely, except for one, which was unable to eject its spare belly-mounted gasoline tanks. As the plane circled the carrier, refusing the order to ditch and struggling to jettison its belly tank, the rest of the aircraft had already been stowed beyond the forward wire barriers.
With the aircraft stored away, the plane was given the greenlight to attempt a landing, some forty-five minutes before sunset. As the plane caught the first arresting gear, the gasoline tank detached, skidded down the flight deck, hit a crewman, and exploded, killing the man. The explosion sprayed burning gasoline onto the parked planes, and set alight the wooden flight deck. The fire forced the evacuation of the bridge, and the engines were cut to deny the fire wind. It appears that the pilot of the landing plane escaped without injury. As a result of the damage sustained from this accident, Admiralty Island was ordered to detach from the task group and to retire to the West Coast. On 21 July, she was detached from Task Group 30.8, and she steamed for Guam, where she unloaded her cargo, and refueled.
After refueling, Admiralty Islands proceeded to the West Coast, arriving at San Diego on 11 August, before heading northwards to San Pedro for refit. Most of the planned alterations were cancelled, as a result of the Japanese surrender being announced on 15 August. Nonetheless, repairs were conducted, and on 1 September, she was assigned to join the "Magic Carpet" fleet, which repatriated servicemen from throughout the Pacific.
She conducted "Magic Carpet" runs until 24 April 1946, when she was decommissioned. She was struck from the Navy list on 8 May, and the hull was sold on 2 January 1947 to the Zidell Machinery and Supply Company of Portland, Oregon. She was ultimately broken up just miles from where she was constructed. Admiralty Islands received three battle stars for her World War II service.