American Civil War: USS Monitor and CSS Virginia (rebuilt from the engines and lower hull of the USS Merrimack) fight to a draw in the Battle of Hampton Roads, the first battle between two ironclad warships.

The American Civil War was a civil war in the United States between the Union and the Confederacy, which was formed in 1861 by states that had seceded from the Union to preserve slavery in the United States, which they saw as threatened because of the election of Abraham Lincoln and the growing abolitionist movement in the North. The war ended with Union victory, the dissolution of the Confederacy and the abolition of slavery, freeing four million African Americans.