From the end of the 1840s, the introduction of steam power brought less dependence on the wind in battle and led to the construction of screw-driven wooden-hulled ships of the line; a number of purely sail-powered ships were converted to this propulsion mechanism. However, the rise of the ironclad frigate, starting in 1859, made steam-assisted ships of the line obsolete. The ironclad warship became the ancestor of the 20th-century battleship, whose very designation is itself a contraction of the phrase "ship of the line of battle" or, more colloquially, "line-of-battle ship".