The "Monitor" and the "Merrimac" were both warships. They were ironclads. They were, that is, built of wood, but they were covered with heavy iron plates. These two vessels fought a battle in the early days of the War between the States.
   The "Monitor" was built by a Swedish engineer for the Northern forces. It was called a "cheese box on a raft." The vessel had a flat iron deck only slightly above water level. In the center was a revolving turret with two guns. The "Monitor" was much smaller than the "Merrimac."
   The "Merrimac" belonged to the South­ern forces. The engineers who had built it had cut off the sides of an old vessel, cov­ered the vessel with iron, and mounted ten guns. This ironclad had a pointed cast-iron bow which could easily ram a hole in the side of a wooden ship.
   The "Merrimac" had sunk two Northern vessels the day before its battle with the "Monitor." But they were wooden vessels. It could not harm the "Monitor." After four hours of fighting, neither vessel had won the battle. The "Merrimac" then steamed away, badly damaged.
   The battle was only a small one, but it was one of the most important naval battles ever fought. It was the beginning of the change from wooden vessels to great steel warships.