The modern battleship traces its ancestry to the first-rate ships-of-the-line of the sailing era. Until recently, modern battleships served on the front lines of sea battles throughout the world. They have largely been replaced by aircraft carriers.
The last battleships built in the United States were of the Iowa class. The four Iowa-class vessels entered service in the 1940s. The U.S. Navy modernized them in the 1980s, then removed them from service in the 1990s. These steel-hulled ships measured 270 m (885 ft) and traveled at an unprecedented speed of 33 knots.