 warship, any ship built or armed for naval combat. The forerunners of the modern warship were the men-of-war of the 18th and early 19th cent., such as the ship of the line, frigate, corvette, sloop of war (see sloop), brig, and cutter. With the advent of steel construction and steam propulsion in the latter half of the 19th cent., warships evolved into their modern form. The key naval vessels used in modern warfare are the aircraft carrier and the submarine; other modern warships include the battleship, cruiser, destroyer, gunboat, and torpedo boat.ship of the linefrigatecorvettesloopbrigcutteraircraft carrier submarine battleshipcruiserdestroyergunboat torpedo boat  See Jane's Fighting Ships (pub. annually since 1897).

 torpedo, in naval warfare, a self-propelled submarine projectile loaded with explosives, used for the destruction of enemy ships. Although there were attempts at subsurface warfare in the 16th and 17th cent., the modern torpedo had its origin in the efforts of David Bushnell, who, during the American Revolution, experimented with a submarine for attaching underwater explosives to British ships. His attempts failed, but later Robert Fulton experimented with similar ideas. In the 19th cent. torpedoes developed at first as stationary mines placed in the water; these were used extensively by the Russians in the Crimean War and by the Confederacy in the U.S. Civil War. The first truly self-propelled torpedo was designed and built at Fiume in 1866 by Robert Whitehead, an Englishman. It was driven by a small reciprocating engine run by compressed air; a hydrostatic valve and pendulum balance, connected to a horizontal rudder, controlled the depth at which it ran. Directional accuracy was achieved in 1885 when John Adams Howell developed the gyroscope to control the vertical rudder. Torpedoes were used by Japan in the Russo-Japanese War and were widely employed in World War I. The torpedoes used in World War II were usually 20 to 24 ft (6.1—7.3 m) long, carrying up to 600 lb (272 kg) of explosives at a speed of 50 knots for more than 10,000 yd (9,144 m). The type of torpedo used in World War II has been largely superseded by the homing torpedo. In contrast to the older type, which traveled in a straight line on a preset course, the homing torpedo automatically changes its course to seek out its target. Most homing torpedoes are activated by sounds coming from the target (e.g., propeller or machinery noises), and they follow the sounds until making contact with the target. A homing torpedo runs through three phases: the enabling run, which takes it to the vicinity of the target; the search pattern, in which it maneuvers to find the target; and the homing, in which it pursues the target. The modern torpedo is generally propelled by an electric motor, but some of the newer, faster, high-diving torpedoes, designed for effectiveness against nuclear submarines, have solid-propellant-driven turbines. Some also may be equipped with nuclear warheads. Torpedoes can be fired from shore stations, surface vessels, and aircraft, as well as from submarines.submarine  See Bureau of Naval Personnel, Principles of Naval Ordnance and Gunnery (1959); R. Fulton, Torpedo War and Submarine Explosions (1810, repr. 1971).

 submarine, naval craft capable of operating for an extended period of time underwater. Submarines are almost always warships, although a few are used for scientific or business purposes (see also submersible). submersible  Development of the Modern Submarine  The first submarine used in combat (1776) was invented in 1773 by David Bushnell, an American. This vessel was a small, egg-shaped craft constructed of wood and operated by one man who turned a propeller. The vessel was submerged by admitting water, and it was surfaced by forcing out the water with a hand pump. Many of Bushnell's principles were later used by Robert Fulton for the construction of his Nautilus, a submarine successfully operated (1800—1801) on the Seine River and at Le Havre. On one occasion the inventor remained submerged for 6 hr, receiving air through a tube that extended to the surface. Later Fulton devised and used a spherical tank of compressed air to replenish the air in the submarine. This device, horizontal rudders, the screw to keep water out during submerged operation, and other features of Fulton's submersible vessel made it a forerunner of the modern submarine. In the U.S. Civil War the Confederates used several submersible craft, all named David, fitted with a mine at the end of a spar that protruded from the bow. In 1864 one of these craft destroyed a Union vessel in Charleston harbor but was itself lost with its crew.  The development of the modern submarine in the United States was advanced considerably by the work of John Holland and Simon Lake. One of Holland's submarines was propelled on the surface by a gasoline engine and by electric motors powered by storage batteries when submerged. The craft was 54 ft (16 m) long and had a top speed of 6 knots and a crew of six. In 1900 it became the U.S. Navy's first submarine. Holland's efforts were especially important in the development of submergence by water ballast and of horizontal rudders for diving. Lake's Argonaut, built in 1897, became the first submarine to navigate extensively in the open sea when it made (1898) a trip through heavy storms from Norfolk, Va., to New York City. However, the Argonaut was not accepted by the U.S. Navy, and it was not until several European governments had made use of Lake's talents that the U.S. government employed him.

 aircraft carrier, ship designed to carry aircraft and to permit takeoff and landing of planes. The carrier's distinctive features are a flat upper deck (flight deck) that functions as a takeoff and landing field, and a main deck (hangar deck) beneath the flight deck for storing and servicing the aircraft. The aircraft carrier emerged after World War I as an experimentally modified cruiser. The first aircraft carrier built (1925) from the keel up as an aircraft carrier for the U.S. navy was the U.S.S. Saratoga. The aircraft carrier remained an experimental and untested war vessel until World War II, when the Japanese destroyed or drove out of the East Asian waters the British, Dutch, and U.S. navies with carrier-borne aircraft. By 1942 the aircraft carrier had replaced the battleship as the major unit in a modern fleet, and in World War II it was indispensable in naval operations against a sea- or land-based enemy. The battle of the Coral Sea (1942) was fought by naval aircraft, and the two opposing fleets never came within gunshot range of each other. After World War II aircraft carriers were enlarged and improved by the British and U.S. navies and became the nucleus of the standard naval combat formation. With the introduction of nuclear-powered carriers in the 1960s, extremely lengthy voyages became possible because such carriers do not need regular refueling.  See N. Polmar, Aircraft Carriers (1969); G. L. Pawlowski, Flat-Tops and Fledglings (1971); C. G. Reynolds, The Fast Carriers (1978).