DESTROYER

fast naval vessel that has served a variety of functions since the late 19th century. The term destroyer was first used for the 250-ton vessels built in the 1890s to protect battleships from torpedo boats. These torpedo-boat destroyers, as they were called, then became super torpedo boats themselves, so that, by World War I, they were commonly deployed ahead of the battle fleet to scout for the enemy fleet, beat back its destroyers with cannon fire, and then launch torpedoes against its battleships and cruisers. As the submarine became the principal torpedo-launching vessel, destroyers were equipped with hydrophones and depth charges to protect merchant-ship convoys and battle fleets against submarine attack. In World War II, with the addition of radar and antiaircraft guns, this escort role was expanded to include air defense. Since 1945 the destroyer's dual antiaircraft-antisubmarine role has continued through the transition to guided missiles. A modern destroyer's armament consists of surface-to-air missiles, antisubmarine torpedoes, antiship missiles, and one or two main guns of about four or five inches in calibre. Many destroyers carry submarine-hunting helicopters, and some carry cruise missiles. Modern destroyers range from 4,000 to 7,000 tons in displacement, are capable of speeds of more than 30 knots, and carry crews of about 300.