Caldwell-class destroyer

Two were scrapped during the 1930s, but four survived to serve throughout World War II, three of these in service with the Royal Navy under the Destroyers for Bases Agreement and the fourth as a high speed transport.

There were differences in appearance; Caldwell, Craven and Manley were built with four "stacks" (funnels), while Gwin, Conner and Stockton had only three.

[5] Manley was converted to a prototype high-speed destroyer transport (hull classification symbol APD) in 1939, with her forward stacks and boilers removed to give her the capacity to lift 200 Marines and four 11 m (36 ft) Higgins assault boats (LCP(L), LCP(R), or LCVP).

The armament repeated that of the preceding Sampson-class of "thousand tonners", and would be retained in the subsequent mass production "flush deckers".

Conner and Stockton, built by Cramp, followed the class's original design, with three-shaft direct drive steam turbines.

A geared cruising turbine was provided on the center shaft for fuel economy at low and moderate speeds.

The latter were connected via an experimental "electric speed reducing gear", a forerunner of the turbo-electric drive that would be used on several US battleships and aircraft carriers built from World War I through the 1920s.