A Ship of the line was a kind of warship. Most ships of the line were built between the 17th and 19th century. At that time, battles were fought by many such ships, which sailed in a line. At first, such ships were sailing boats, but from about the 1840s, steam-driven ships of the line were built. The steam-powered ships of the line were still made of wood. From about 1859, the Ironclad warship replaced them. 