USS Monitor was an ironclad warship built for the Union Navy during the American Civil War and completed in early 1862, the first such ship commissioned by the Navy.^[​a] Monitor played a central role in the Battle of Hampton Roads on 9 March under the command of Lieutenant John L. Worden, where she fought the casemate ironclad CSS Virginia (built on the hull of the scuttled steam frigate USS Merrimack) to a stalemate. The design of the ship was distinguished by its revolving turret, which was designed by American inventor Theodore Timby; it was quickly duplicated and established the monitor class and type of armored warship built for the American Navy over the next several decades.