One of the key areas of the blockade was around the areas called Hampton Roads. If the South broke the blockade, that could lead to an attack up river to Washington D.C. From the North, the blockade could keep vital resources from the Southern army and also lead to an attack on Richmond, the capitol of the Confederacy. Both wanted to control this area.
The Monitor, lead by Captain John Worden, was launched on January 30, 1862. Upon hearing of the launch, the South launched the Merrimack under Captain Franklin Buchannan, even though it was not completely outfitted with its armor. They both were steaming toward the area of the Hampton Roads. The Merrimack arrived at Hampton Roads on March 9th, 1862. The Monitor was delayed by very choppy sea on the Atlantic and almost sunk on the way to Hampton Roads. These seas delayed the Monitor for nearly a day.