Built for service during World War II, the ship was launched in May 1944, and commissioned in June, and served as a training and transport carrier.

[4] 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.

[8] She was launched on 22 May 1944; sponsored by Mrs. Margaret Anna McLaren Grant, the wife of United States Representative Robert A.

Grant; transferred to the United States Navy and commissioned on 24 June 1944, with Captain William Lawrence Erdmann in command.

There, she discharged the rest of her cargo, and took on a load of 112 passengers and 41 damaged aircraft, ferrying them back to the West Coast.

On 14 August, she took on Composite Squadron 93 (VC-93), and began pilot qualifications, serving as a training carrier off the California coast.

Between January and June 1945, 1,332 pilots earned their qualifications onboard Matanikau, and 12,762 landings were conducted on her flight deck during this period.

During her period as a training carrier, Captain Francis Benedict Johnson took over command of the vessel, a position that he would hold for the rest of the war.

She operated off the west coast of Japan, covering landings by U.S. forces, including the Eighth Army at Aomori on 25 September.

Following the landings, she steamed south, and departed Tokyo Bay on 30 September, making stops at Guam and Pearl Harbor, before arriving back at San Francisco on 23 October.

There, the marines served in an advisory role, supporting the Kuomintang Republic of China in the Chinese Civil War.

She was mothballed as part of the Pacific Reserve Fleet, and she was reclassified as an escort helicopter aircraft carrier, CVHE-101 on 15 June 1955.