USS Monitor was the first ironcla warship commissioned by the United States Navy. She is most famous for her participation in the first-ever naval battle between two ironclad warships, the Battle of Hampton Roads on March 9, 1862 during the American Civil War, in which Monitor fought the ironclad CSS Virginia of the Confederate States Navy. ‘‘Monitor’’ was the first in a long line of Monitor-class U.S. warships and the term "monitor" describes a broad class of European harbor defense craft.