Fast naval vessel smaller than a frigate. In the 18th–19th century corvettes were three-masted ships with square rigging and carried about 20 guns on the top deck. Often used to send dispatches within a battle fleet, they also escorted merchant ships. Early U.S. corvettes won distinction in the War of 1812. They disappeared as a class after the shift to steam power in the mid-19th century, but in World War II the term was applied to small armed vessels that served as escorts for convoys. Modern corvettes, usually displacing 500–1,000 tons (454–900 metric tons) and armed with missiles, torpedoes, and machine guns, perform antisubmarine, antiaircraft, and coastal-patrol duties in small navies.