The battle between the Monitor and the Merrimack can be seen as a draw in a short-term, however, it was really a victory for the US in the long term.
During the Battle of Hampton Roads, the Merrimack was sent by the South to try to break the US blockade that was situated around the Southern Coastal lines. As the Merrimack was a Ironclad ship (A wooden ship that was fitted with metal armor), and Armor-Piercing shells were not created yet, many of the cannon-balls were bouncing off of the ship. This prompted the US to send their own ironclad, called the "Monitor", which, like the Merrimack, was armored with iron plates, but the key feature was the revolving turret. Through the battle, the Monitor's turret was jammed after taking considerable hits from the Merrimack, but accomplished the goal of routing the Merrimack.
So in the end, it could be seen as a draw, as neither was able to destroy each other.
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