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).

She moved to Portland, Oregon, for final fitting out, before continuing on to Seattle, Washington, for supplies, and then sailing on to San Diego, California.

After passing through the Panama Canal and stopping briefly at Norfolk, Virginia, she arrived in New York on 6 June and entered the Brooklyn Navy Yard.

The outbreak of the Korean War on 25 June interrupted plans for anti-submarine warfare training over the summer, leading to Sicily's deployment to East Asian waters on 2 July.

[6] Sicily made a fourth cruise in East Asian waters beginning on 14 July 1953, shortly before the Korean Armistice Agreement ended the fighting in Korea.

[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.