Major branch of the U.S. military forces, charged with defending the nation at sea and maintaining security on the seas wherever U.S. interests extend.
The Continental Navy was established by the Continental Congress in 1775. It was disbanded in 1784, but the harassment of U.S. merchant ships by Barbary pirates prompted Congress to establish the Department of the Navy in 1798. The navy took part in the War of 1812 and was later important in the Union victory in the American Civil War. Sea victories during the Spanish-American War (1898) led to a period of steady growth. In World War I, its duties were limited to troop transport, minelaying, and escorting merchant ships. The Japanese attack on the naval base at Pearl Harbor (1941) led to U.S. entry into World War II, in which, in addition to antisubmarine and troop transport duties, the navy conducted amphibious assaults in the Pacific theater and along the European coast. Aircraft carriers proved decisive in battles with Japanese forces in the Pacific, and they are still the backbone of the navy's fleets. Since World War II it has remained the largest and most powerful navy in the world. The Department of the Navy, a branch of the Department of Defense, is headed by a secretary of the navy. The navy includes the U.S. Marine Corps and, during wartime, the U.S. Coast Guard . In 2000 there were almost 400,000 Navy personnel on active duty, excluding the Marine Corps and Coast Guard. See also U.S. Naval Academy .