Steam frigates and the smaller steam corvettes were steam-powered warships. The first vessel that can be considered a steam warship was the Demologos, which was launched in 1815 for the United States Navy. Towards the end of the 19th century, the term 'frigate' fell out of use. Armoured vessels were designated as either 'battleships' or 'armoured cruisers', while unarmoured vessels including frigates and sloops were classified as 'unprotected cruisers'. The only surviving screw frigate is the Danish Jylland.