[Illustration: Portrait.] John Ericsson. [Illustration: Cross section of monitor.] Sectional View of Monitor through Turret and Pilot House. For three hours the iron-clads fought. The Merrimac's shot glanced harmlessly off the round turret, while her attempts to run the Monitor down failed. Meanwhile the big guns in the Monitor's turret, firing every seven minutes, were pounding the ram's sides with terrible blows. The Merrimac's armor was at points crushed in several inches, but nowhere pierced, About noon the fight stopped, as if by mutual consent. It was a drawn battle, but the career of the Merrimac had ended. Upon McClellan's advance, in May, she was blown up. The Monitor received no serious injury in this action, but the next December she foundered in a storm off Cape Hatteras. The invention of the Monitor revolutionized naval warfare, and set European nations to building the ponderous iron-clad navies of the present day. The United States Government soon contracted for twenty single-turret monitors, and four double-turreted ones with fifteen-inch guns. The Confederates now went to building iron-clads on the model of the Merrimac. On the morning of January 31, 1863, the iron-clads Palmetto State and Chicora steamed out of Charleston Harbor, in a dense fog, and attacked the blockading fleet of wooden vessels. After ramming one ship and sending a shot through the boiler of another, they put back to port. In April, Admiral Dupont tried to seize Charleston Harbor with his fleet of seven monitors and two iron-clads. In a two hours' action the monitors were seriously injured by the heavy guns of the forts, and the fleet withdrew. In August, land batteries reduced Fort Sumter almost to ruins, and in the following month Fort Wagner was abandoned. June 17th, the iron-clad Atlanta, armed with a torpedo at the end of a spar, ran down from Savannah to engage with two monitors guarding the mouth of the river. She got aground, rendering the torpedo useless. The fifteen-inch guns of the monitors pierced her armor, and in a few minutes she surrendered.