Commissioned in 1855 as the U.S.S. Merrimack, she served as flagship of the Pacific Squadron from 1857 to 1859 after service in the Caribbean and Europe. After the hull had burned to the waterline, engineers salvaged the hull and machinery to create the central battery frigate CSS Virginia. Instead of a trial run, Virginia engaged in battle with the 24 gun USS Cumberland, which would be her first victim. However, the Confederate ironclad had suffered some damage; while undergoing repairs in Norfolk, she was made a flagship of the Confederate States Navy. Unfortunately, her deep draft precluded her from moving up the James river which she was charged with protecting. She was blown up on May 11, 1862.