USS Thetis Bay was commissioned on April 21, 1944 as a Casablanca-class aircraft carrier. Brief shakedown training took place in San Diego, followed by a trip to San Pedro to load passengers and planes bound for various destinations in the Pacific. She arrived at Pearl Harbor on June 11, 1944 and then continued on to Kwajalein via Makin and Majuro.
She picked up the 50th Engineer Battalion of the Army and took them to Pearl Harbor, picking up aircraft that needed repair. She headed back to Alameda with aircraft in tow, and then proceeded to Terminal Island for a three-week yard stint. The ship made many more trips from California to various Pacific bases before the war was over.
After a stint as a Magic Carpet carrier, responsible for bringing home veterans, the ship was placed in reserve at Bremerton in 1946. In May of 1955, Thetis Bay began modifications to become the first assault helicopter carrier. In July, she was reclassified as CVHA-1 and was recommissioned a year later.
The carrier was sent to Long Beach in September, and was used for training exercises. She helped with the 1959 Taiwan floods, and was transferred to the Atlantic Fleet in 1961. She was involved in the Cuban Missile Crisis, helped with the Haiti hurricane relief in 1963, and was decommissioned and sold for scrap in 1964.