[Footnote: When the United States navy-yard at Norfolk was given up, the steam-frigate Merrimac, the finest in the service, was scuttled. The Confederates afterward raised this vessel, razed the deck, and added an iron prow and a sloping roof made of railroad iron. The ship thus prepared looked not unlike a great house sunk in the water to the eaves. The Federals knew that the Merrimac was fitting for battle, and her coming was eagerly expected. ] Warned by the fate of the Cumberland, the captain of the frigate Congress ran his vessel ashore, but the Merrimac, taking a position astern, fired shells into the frigate till the helpless crew were forced to surrender. At sunset, the Merrimac returned to Norfolk, awaiting, the next day, an easy victory over the rest of the Union fleet. All was delight and anticipation among the Confederates; all was dismay and dismal foreboding among the Federals. That night the Monitor arrived in harbor. [Footnote: This "Yankee cheese-box," as it was nicknamed at the time, was the invention of Captain Ericsson. It was a hull, with the deck a few inches above the water, and in the centre a curious round tower made to revolve slowly by steam power, thus turning in any direction the two guns it contained The upper part of the hull, which was exposed to the enemy's fire, projected several feet beyond the lower part, and was made of thick white oak, covered with iron plating six inches thick on the sides and two inches on deck] Though of but nine hundred tons burden, she prepared to meet her adversary of five thousand. Early in the morning the Merrimac appeared, moving toward the steam-frigate Minnesota. Suddenly, from under her lee, the Monitor darted out, and hurled at the monster two one hundred and sixty-eight pound balls. Startled by the appearance of this unexpected and queer-looking antagonist, the Merrimac poured in a broadside, such as the night before had destroyed the Congress, but the balls rattled harmlessly off the Monitor's turret, or broke and fell in pieces on the deck. [Illustration: NAVAL DUEL BETWEEN THE MONITOR AND THE MERRIMAC] Then began the battle of the iron ships. It was the first of the kind in the world. Close against each other, iron rasping on iron, they exchanged their heaviest volleys. Five times the Merrimac tried to run down the Monitor, but her huge beak only grated over the iron deck, while the Monitor glided out unharmed. Despairing of doing anything with her doughty little antagonist, the Merrimac now steamed back to Norfolk. [Footnote: As the Merrimac drew off she hurled a last shot, which, striking the Monitor's pilot-house, broke a bar of iron nine by twelve inches, seriously injuring the eyes of the gallant commander, Lieutenant Worden, who was at that moment looking out through a narrow slit and directing the fire of his guns]