The destroyer of World War II was a fast unarmored warship of 1000 to 3000 tons displacement. It was typically armed with four- or five-inch guns, torpedoes, antisubmarine weapons, and light antiaircraft weapons for point defense.
Destroyers were originally developed to protect capital ships from torpedo boats. This required rapid-firing weapons and enough speed to effectively screen the larger ships. With the advent of the submarine, the destroyer became the principal antisubmarine screening ship, and depth charges and sound gear were added to its inventory. During the First World War, the sound gear took the form of sensitive hydrophones, which could detect noises from a nearby submerged submarine. Most of the major powers had independently developed sonar, which uses an active signal to more precisely locate submarines, by the start of the Second World War.
The antisubmarine mission continued through World War II, but destroyers proved to be the workhorses of the fleet. Their main armament shifted to dual-purpose weapons useful against aircraft (of which the best was the U.S. 5”/38 gun) and Allied destroyers acquired sophisticated radars. Because of their shallow draft, destroyers were useful for shore bombardment, because they could get in close to shore for accurate gunnery.
American pre-war destroyers were almost universally top heavy and very uncomfortable for their crews. The Fletchers, built during the war, reversed this trend and were very capable ships. Japanese destroyers were also very capable and did not suffer from stability problems, largely because the Japanese had learned this lesson from the Tomozuru Incident, in which a torpedo boat capsized in a typhoon in the 1930s. (Two pre-war American destroyers would capsize in a typhoon late in the war.) American destroyers had powerful antiaircraft armament but miserable torpedoes, while Japanese destroyers were almost the opposite, with poor antiaircraft and the best torpedo in the world — the Long Lance. British destroyers started the war with even worse antiaircraft armament than the Japanese, but better torpedoes than the Americans, and they excelled at antisubmarine warfare.
When steaming at their maximum speed of better than 30 knots, destroyers consumed fuel prodigiously. American practice was to maintain an equally lavish fleet train with enough tanker support to keep the destroyers going. The Japanese, with fewer tankers, often refueled their destroyers from the larger warships in the task force.
References
The Pacific War Online Encyclopedia (c) 2007 by Kent G. Budge. Index