Ironclads were warships built of wood or iron and covered with thick plates of iron. During the 1820s naval guns that fired explosive shells (versus solid cannonballs) were developed. Because the new shells could easily destroy the hull of a wooden ship, the navy began developing ways to protect its battleships from this superior ammunition. Ships clad in iron could better sustain the fire of explosive shells.
The first battle between two ironclads was staged during the American Civil War (1861–65). On March 9, 1862, the Union's Monitor, originally built as an ironclad and equipped with a revolving gun turret, faced the Confederacy's Virginia. (The Virginia was made by raising the sunken federal boat the Merrimack and covering the wooden vessel with iron plates.) The ships met at Hampton Roads, Virginia, a channel that empties into Chesapeake Bay. Though the outcome was indecisive, the Monitor 's performance in the battle was sufficient to warrant the U.S. Navy's production of a fleet of ironclad ships. The March 1862 battle off the coast of Virginia marked the beginning of modern naval warfare.
The use of sturdier materials in shipbuilding, along with the steam-power and the screw propeller, all of which were used by Civil War ironclads, greatly improved the efficiency of maritime commerce after the war. In fact John Ericsson (1803–1899), the designer of the Monitor, had also developed the screw propeller.
See also: Civil War