USS Fanshaw Bay (CVE-70) was a Casablanca-class escort carrier of the United States Navy. She was named after Fanshaw Bay, located within Cape Fanshaw, of the Alexander Archipelago in the Territory of Alaska. The cape was given its name by Charles Mitchell Thomas, who was mapping the area, in 1887. Built for service during World War II, the ship was launched in November 1943, and commissioned in December, and served in support of the Mariana and Palau Islands campaign, the Battle off Samar, and the Battle of Okinawa. Postwar, she participated in Operation Magic Carpet. She was decommissioned in August 1946, when she was mothballed in the Pacific Reserve Fleet. Ultimately, she was sold for scrapping in September 1959.

Fanshaw Bay was a Casablanca-class escort carrier, the most numerous type of aircraft carriers ever built, and was designed specifically to be mass-produced using prefabricated sections, in order to replace heavy early war losses. Standardized with her sister ships, she was 512 ft 3 in (156.13 m) long overall, had a beam of 65 ft 2 in (19.86 m), and a draft of 20 ft 9 in (6.32 m). She displaced 8,188 long tons (8,319 t) standard, 10,902 long tons (11,077 t) with a full load. She had a 257 ft (78 m) long hangar deck and a 477 ft (145 m) long flight deck. She was powered with two Skinner Unaflow reciprocating steam engines, which drove two shafts, providing 9,000 horsepower (6,700 kW), thus enabling her to make 19 knots (35 km/h; 22 mph). The ship had a cruising range of 10,240 nautical miles (18,960 km; 11,780 mi) at a speed of 15 knots (28 km/h; 17 mph). Her compact size necessitated the installment of an aircraft catapult at her bow, and there were two aircraft elevators to facilitate the movement of aircraft between the flight and hangar deck: one each fore and aft.

One 5 in (127 mm)/38 caliber dual-purpose gun was mounted on the stern. Anti-aircraft defense was provided by eight Bofors 40 mm (1.6 in) anti-aircraft guns in single mounts, as well as twelve Oerlikon 20 mm (0.79 in) 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 (0.79 in) cannons, and the amount of Bofors 40 mm (1.6 in) guns had been doubled to sixteen, by putting them into twin mounts. These modifications were in response to increasing casualties due to kamikaze attacks. Casablanca-class escort carriers were designed to carry 27 aircraft, but the hangar deck could accommodate more. During the Mariana and Palau Islands campaign, the beginning of the Philippines campaign, and the Battle off Samar, she carried 16 FM-2 Wildcat fighters, and 12 TBM-1C Avenger torpedo bombers, for a total of 28 aircraft. However, during the Battle of Okinawa, she carried 24 FM-2 fighters and 6 TBM-3 torpedo bombers for a total of 30 aircraft.

The escort carrier was laid down on 18 May 1943, under a Maritime Commission contract, MC hull 1107, by Kaiser Shipbuilding Company, Vancouver, Washington. She was named Fanshaw Bay, as part of a tradition which named escort carriers after bays or sounds in Alaska. She was launched on 1 November 1943; sponsored by Mrs. Lorna V. Kenworthy, the wife of Captain Jesse L. Kenworthy Jr., who was the executive officer of the battleship Oklahoma during the Attack on Pearl Harbor. She was transferred to the United States Navy and commissioned on 9 December 1943, with Captain Douglass Pollock Johnson in command.

Upon being commissioned, Fanshaw Bay took on armaments at Port Townsend, Washington on 31 December, and proceeded on a shakedown cruise down the West Coast. During this period, she stopped at Port Angeles, Washington from 6 January 1944 to 8 January, along with another pause at San Francisco, California between 11 and 16 January, where she took on a load of aircraft. She was also assigned to become the flagship of Carrier Division 25, commanded by Rear Admiral Gerald F. Bogan. She departed from San Francisco on 16 January, ferrying her load to Gladstone, Queensland, arriving on 2 February. On her return trip, she touched at Brisbane from 8 to 12 February, and at Nouméa from 15 to 16 February.

Upon returning, she underwent maintenance and her crew underwent leave at San Diego from 4 March to 6 April. There, Fanshaw Bay received her aircraft contingent, originally intended to be Composite Squadron 4 (VC-4), but switched to Composite Squadron 68 (VC-68), which consisted of 16 FM-2 fighters and 10 TBM-1C torpedo bombers. She departed San Diego on 6 April, accompanied by the seaplane tender Orca, making a stop at Pearl Harbor on 10 April, and arriving at Majuro on 20 April. En route, on 11 April, one of her torpedo bombers crashed in an accident, with its crew being rescued by Orca. Upon arriving at Majuro, she began conducting antisubmarine patrols, along with the destroyer escorts John C. Butler, Raymond, and Richard M. Rowell. Ten days of patrols returned no contacts, and she retired to Pearl Harbor.

On 29 May, she sortied from Pearl Harbor, bound for Eniwetok Atoll, where she acted as the flagship of Task Group 52.14, which was assigned to support the upcoming Mariana and Palau Islands campaign. En route, two of her Wildcats were lost, and another was slightly damaged, through accidents. She began combat operations on 11 June, some 30 mi (48 km) west of Saipan, providing aerial reconnaissance, close air support, and antisubmarine patrols in support of the Battle of Saipan. On 15 June, at 17:15 in the late afternoon, the officers of Fanshaw Bay received a report of five Japanese aircraft proceeding towards her task group 71 mi (114 km) to her southwest. Fighters were scrambled, and the aircraft were intercepted 36 mi (58 km) away, harrying them as they quickly proceeded towards the carriers. Four of them were shot down, although a fifth aircraft was able to drop a torpedo aimed at Fanshaw Bay at 18:12. Fortunately for the carrier, the Japanese plane approaching from the starboard bow, perhaps disrupted by the anti-aircraft fire, dropped its torpedo at a slight turn. Therefore, Fanshaw Bay engaged in a hard right turn, easily dodging the torpedo. The Japanese aircraft was subsequently shot down at 18:15.

On 17 June, one of Fanshaw Bay's torpedo bombers conducting antisubmarine patrols crashed shortly after takeoff, veering port into the sea. A large explosion was triggered, likely from the detonation of one of the bomber's depth charges, killing all three of its crew. Later that day, another torpedo bomber was lost, and although two of the crew were recovered, the radioman drowned with the aircraft. In the late afternoon, the task group detected about seventy Japanese aircraft approaching quickly from the southeast, 40 mi (64 km) out. Fighters were scrambled, and Fanshaw Bay launched fourteen Wildcats to supplement the thirty-two launched by the other escort carriers. Her fighters, intercepting the planes, shot down one. Nonetheless, the Japanese force penetrated the air screen, and made for the carriers. Early on in the attack, the Japanese planes focused on Fanshaw Bay and White Plains. Her anti-aircraft guns provided adept assistance, shooting down three planes, and damaging two more.