In the early 1940s, as the
United States Navy expanded in response to the threat of involvement in
World War II, a number of civilian
passenger ships and some
freighters were acquired, converted to transports and given
hull numbers in the AP series. Some of these were outfitted with heavy boat
davits and other arrangements to enable them to handle
landing craft for
amphibious assault operations. In 1942, when the AP number series had already extended beyond 100, it was decided that these amphibious warfare ships really constituted a separate category of warship from conventional transports. Therefore, the new classification of
auxiliary personnel, attack (APA) was created and numbers assigned to fifty-eight APs (AP Nos. 2, 8-12, 14-18, 25-27, 30, 34-35, 37-40, 48-52, 55-60, 64-65 and 78-101) then in commission or under construction. APA are in the classification of US Navy
auxiliary ships. The actual reclassification of these ships was not implemented until February 1943, by which time two ships that had APA numbers assigned ( and ) had been lost. Another two transports sunk in 1942, and , were also configured as attack transports but did not survive to be reclassified as such. As World War II went on, dozens of new construction merchant ships of the
United States Maritime Commission's S4, C2, C3 and VC2 ("
Victory") types were converted to attack transports, taking the list of APA numbers to 247, though fourteen ships (APAs 181-186 and APAs 240-247) were cancelled before completion. In addition, as part of the 1950s modernization of the Navy's amphibious force with faster ships, two more attack transports (APA-248 and APA-249) were converted from new
Type C4-class ships, the s.
Classes Classes of attack transports included: • (2 ships) • both built by the
Furness Shipbuilding Company and
acquired by the navy in 1940 • , originally AP-10 • , AP-11 • (5 ships) • all built by the
Alameda Works Shipyard as merchant ships ca. 1918 and acquired by the navy in 1940 • , AP-12 • • , AP-14 • , AP-15 • , AP-16 • , AP-17 • • • • (8 ships) •
Type P1 ship • (2 ships) •
Type S4 ship • (32 ships) •
Victory Ship • (117 ships) •
Type C2 ship • (3 ships) • (4 ships) •
Type C3 ship • (3 ships) • (4 ships) • (2 ships) • (9 ships) • (34 ships) • (7 ships) •
Type C4 ship • (2 ship) ==In use==