Destroyer transport

High-speed transports were converted destroyers and destroyer escorts used to support US Navy amphibious operations in World War II and afterward. They received the US Hull classification symbol APD; "AP" for transport and "D" for destroyer.

APDs were intended to deliver small units such as Marine Raiders, Underwater Demolition Teams and United States Army Rangers onto hostile shores. They could carry up to a company size unit (200 troops). They could also provide gunfire support if needed. The USS Manley was officially designated the Navy's first high-speed transport on 2 August 1940 when she became APD-1.

Before United States entered World War 2, as newer and more modern destroyers began joining the fleet, some of the older ships were assigned to other duties such as tending seaplanes, laying or sweeping mines, or for a newer innovation in modern warfare, carrying fully equipped troops for assault landings as fast transports.

The first group of APDs (APD-1 through APD-36) were converted from one Caldwell-class, 17 Wickes-class, and 14 Clemson-class "flush-deck" destroyers built during and after World War I. Some of these had been previously converted to aircraft tenders or other uses.

In the conversion, the two forward boilers (out of four) were removed along with their smokestacks (reducing speed to 25 knots). Accommodation for 200 troops was installed in the former engine spaces. The original armament of four 4" guns, one 3" AA gun, and twelve 21" torpedo tubes was replaced with three modern 3" AA guns, one 40 mm AA gun, and five 20 mm AA guns. Two depth charge racks and up to six K-gun depth charge throwers were carried. In place of the torpedo mounts, four davit mounted Landing Craft Personnel (Large) (LCP(L)s) were shipped. Later, the LCP(L)s were replaced by a version with a bow ramp, the Landing Craft Personnel (Ramped).

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