Ironclads was a made for TV movie about the first ever battle between Ironclad ships which which took place during the American Civil War. The story centres on Betty Stuart (played by Virginia Madsen) a southern belle who is spying for the North and becomes involved with the race to complete both ships. The film touches on the development of the two ironclads, the USS Monitor for the North and the CSS Virginia which is more often known as Merrimac(k) as it was built upon the hull of the USS Merrimack and the encounter between the two during the Battle of the Hampton Roads.
The story moves along a quite a good pace and the battle is very watchable. The film is very hard to get hold of and I think has only ever been released on VHS but I have found a copy posted on Youtube and would recommend it, especially for any FSA fans!
For more information on the Battle of the Hampton Roads, the Wikipedia page is a good starting point:
Battle of Hampton Roads