Ordered and constructed during World War II, Tinian never entered active service and was assigned to the Pacific Reserve Fleet, Tacoma after being completed.

In 1941, as United States participation in World War II became increasingly likely, the US Navy embarked on a construction program for escort carriers, which were converted from transport ships of various types.

These proved to be very successful ships, and the Commencement Bay class, authorized for Fiscal Year 1944, were an improved version of the Sangamon design.

[1] They proved to be the most successful of the escort carriers, and the only class to be retained in active service after the war, since they were large enough to operate newer aircraft.

Given the very large storage capacity for oil, the ships of the Commencement Bay class could steam for some 23,900 nautical miles (44,300 km; 27,500 mi) at a speed of 15 knots (28 km/h; 17 mph).

In early June 1958 Tinian was taken in tow at Tacoma, Washington, by the US Navy MSTS tugboat USNS Yuma, destined for San Diego, California.

While very near the Swiftsure Bank lightship, Neah Bay, Washington; at the entrance of the Strait of Juan de Fuca, Yuma developed engine troubles.

She remained in the Navy's inventory, part of the San Diego Group of the Reserve Fleet, until she was struck from the naval register on 1 June 1970.