There was one, and one only. In March 1862, the ironclad CSS Virginia was launched. The Virginia was built on the hull of the USS Merrimack, a Northern ship that the Union had deliberately sunk in the Norfolk Navy Yard to prevent it from being captured. The Confederacy salvaged the hull and converted it to an ironclad using metal from the Tredegar Ironworks at Richmond. By the late winter of 1862, the CSS Virginia was ready, and when she sallied from port on March 7, she inaugurated an entire new phase in naval warfare.