naval craft capable of operating for an extended period of time underwater. Submarines are almost always warships, although a few are used for scientific, business, or other purposes (see also submersible).
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 fitted with a mine at the end of a spar that protruded from the bow. In 1864 one of these craft, the H. L. Hunley, named posthumously for its inventor, 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.
In 1912, E-boats, the first U.S. diesel-engine submarines, were launched. They were 135 ft (41 m) long, had a crew of 23, and were the first to cross the Atlantic. Development continued, and in World War I submarines were for the first time used extensively by both sides. The Germans used 200-ton submarines (U-boats), and later they employed 2,100-ton craft armed with as many as 19 torpedoes. To halt the heavy destruction of shipping by these U-boats the Allied powers resorted to depth charges, Q-ships (armed vessels disguised as merchantmen), and escorted convoys. With the crucial additions of sonar (which uses high-frequency sound waves to find submarines through echo tracking) and radar-equipped air escorts (often carried on small aircraft carriers) these defenses were also used in World War II.
A typical U.S. Navy submarine in World War II was a 300-ft (91-m) craft of 1,450 tons displacement and had a crew of 55. It ran on diesel engines (while surfaced) at a speed of up to 17 knots and on electric motors (while submerged) at a speed of up to 8 knots. The ship was armed with one 3-in. (7.6-cm) dual-purpose gun, several light automatic weapons, and 10 21-in. (53-cm) torpedo tubes. A periscope is an integral part of every submarine. It extends up through the water and by a mirror arrangement provides the observer below with a view of the surface of the sea. Similar in appearance but totally different in purpose is the snorkel apparatus first employed by the Germans and now in general use. It admits air but not water and, by supplying a flow of fresh air and an outlet for foul air, makes it possible for a submarine to remain submerged for as much as nine tenths of a voyage.
In World War II the Allies and neutrals lost some 4,770 ships to submarines, mostly German U-boats; Axis submarines were a significant strategic threat until late in the war. U.S. submarines sank over 550 Japanese ships. Submarines were also used to insert commandos in enemy territory and for rescue operations. The Germans and Japanese exchanged military plans, equipment, and precious metals by submarine as well.
With the advent of atomic power, the submarine underwent major changes in propulsion and striking power. In the nuclear-powered submarine an atomic reactor generates heat that drives a high-speed turbine engine. The first nuclear-powered submarine was the U.S. Nautilus, completed in 1954. Such submarines, with underwater speeds of above 30 knots, can remain submerged for almost unlimited periods of time and have circumnavigated the globe without surfacing. In 1960 the U.S.S. George Washington was the first submarine to fire a missile from a submerged position; the same year the U.S.S. Triton became the first vessel to circumnavigate the world while submerged. The development of nuclear-powered submarines capable of launching missiles without surfacing has greatly expanded the role of the submarine; its mission is no longer restricted to the destruction of ships (including other submarines), but it now also has the role of firing guided missiles (nuclear or conventional) at land targets deep inside an enemy's borders, as U.S. submarines did during the Persian Gulf War. In the 1990s South Anerican drug cartels began using diesel-powered submarinelike vessels to smuggle illegal drugs. Now built largely of fiberglass, these vessels either travel at the surface, with most of the vessel, except for a conning tower, submerged or, in some cases, are capable of traveling fully submerged on batteries, coming to the surface at night to recharge using diesel engines.
- See The British Submarine (1954). ,
- The Submarine and Sea Power (1967). ,
- The Far and the Deep (1967). ,
- Underwater Warfare in the Age of Sail (1978). ,
- Submarines of the Imperial Japanese Navy (1986). ,
- The Death of the U-Boats (1988). ,
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