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).

Despite the fact that the United States was demobilizing much of the armed forces that had been assembled during the war, the newly completed Mindoro would be kept in active service.

[6] In the postwar period, the Navy adopted a combined-arms approach to ASW defense for the fleet and the US coast; escort carriers like Mindoro formed hunter-killer groups, which were supported by patrol craft and blimps like the K class.

[7] She spent the next nine years operating on a similar routine of training exercises and fleet maneuvers, and she was based at Norfolk for this period.

[6] By this time, the Navy had begun replacing the Commencement Bay-class ships with much larger Essex-class aircraft carriers, since the former were too small to operate newer and more effective anti-submarine patrol planes.

Proposals to radically rebuild the Commencement Bays either with an angled flight deck and various structural improvements or lengthen their hulls by 30 ft (9.1 m) and replace their propulsion machinery to increase speed came to nothing, as they were deemed to be too expensive.

She was struck from the naval register on 1 December 1959, sold in June 1960, and then towed to Hong Kong later that year, where she was broken up for scrap.