The first battle between two ironclad naval ships took place on March 9, 1862, between the USS Monitor and the CSS Virginia, formerly the USS Merrimack (often misspelled "Merrimac").
At the opening of the war, the Confederates converted the wooden 40-gun frigate Merrimack into an ironclad and renamed her the Virginia.
On March 8, 1862, she entered Hampton Roads, a channel in southeast Virginia, with five other vessels and gave battle to the Federal fleet of five ships, disabling the Congress (whose magazine afterwards exploded) and ramming the Cumberland so that she sank.
On March 9th, the Virginia encountered the Monitor, an iron turret ship, constructed from the design of John Ericsson and commanded by John L. Worden. The action began at 8:30 a.m. and, after a lengthy combat, ended in a drawn battle. However, the Virginia withdrew and the remainder of the Union fleet was saved.
The battle demonstrated the vulnerability of wooden against armored ships and the advantage of the turret system of housing naval guns.