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.