The Monitor - The Union iron clad warship - One of the first of his kind. Unlike most ships, it wasn't made of wood - making it easy to take them out.
The Merrimack - The Confederates iron clad warship - Also one of the first of his kind. Also unlike most ships, it wasn't made of wood - making it easy to take them out.
March 8-9, 1862.
BOOM!!!
WAR!!!
BOOM!!!
In the end both ships were fine. But it's highly inconclusive who won. What is definite though is that these ships paved the way for modern warships.