a small Union ironclad built in about 100 days to stop the Confederate ship, the Merrimack. The Merrimack, which was a former U.S. wooden warship destroyed two wooden Union ships in the Chesapeake Bay and threatened the Yankee's plan of blockading all Southern ports. The Union built the Monitor and transported it to the Chesapeake. On March 9, 1862, in 4 hours, the Monitor, or the "Yankee cheesebox on a raft," fought the Merrimack "to a standstill."