The Confederate States Navy (CSN) was the naval branch of the Confederate States armed forces established by an act of the Confederate Congress on February 21, 1861. It was responsible for Confederate naval operations during the American Civil War. The two major tasks of the Confederate Navy during the whole of its existence were the protection of Southern harbors and coastlines from outside invasion, and making the war costly for the North by attacking merchant ships and breaking the Union Blockade.
The C.S. Navy could never achieve equality with the Union Navy, and used technological innovation, such as ironclads, submarines, torpedo boats, and naval mines (then known as torpedoes) to gain advantage over the Union Navy. In February 1861, the Confederate Navy had thirty ships, only fourteen of which were seaworthy, while the Union Navy had ninety vessels. The C.S. Navy eventually grew to 101 ships to meet the rise in naval conflicts and enemy threats.
On April 20, 1861, the Union abandoned the Norfolk Navy Yard but did not burn the facility or ships. (The South's other major navy yard was in Pensacola, Florida). Ships left in the Norfolk shipyard, included a screw frigate named USS Merrimack. It was C.S. Navy Secretary Stephen Mallory's idea to armor the upper sides of the Merrimack with iron plate, making it "iron clad". The ship was renamed CSS Virginia and later fought the USS Monitor to a draw in the Battle of Hampton Roads.
As Navy Secretary, Mallory built the C.S. Navy into something very formidable to achieve the goals it needed to win the war, and do even more. A Confederate Congress committee, meeting on August 27, 1862, reported:
In addition to the ships included in the report of the committee, the Navy also had one ironclad floating battery, presented to the Confederate States by the state of Georgia, one ironclad ram donated by the state of Alabama, and numerous privateers making war on Union merchant ships.
President Davis was not confident of his executive authority to issue letters of marque and called a special session of Congress on April 29 to formally authorize the hiring of privateers in the name of the Confederate States. On May 6, the Confederate Congress passed "An act recognizing the existence of war between the United States and the Confederate States, and concerning letters of marque, prizes, and prize goods." Then, on May 14, 1861, "An act regulating the sale of prizes and the distribution thereof," was also passed. Both acts granted the president power to issue letters of marque and detailed regulations as to the conditions on which letters of marque should be granted to private vessels, the conduct and behavior of the officers and crews of such vessels, and the disposal of such prizes made by privateer crews. The manner in which Confederate privateers operated was generally similar to those of privateers of the United States or of European nations.
The 1856, Declaration of Paris outlawed privateering for such nations as Great Britain and France, but the United States had neither signed nor endorsed the declaration. Therefore, privateering was constitutionally legal in both the United and Confederate States, as well as Portugal, Russia, the Ottoman Empire, and Germany. However, the United States did not acknowledge the Confederate States as a nation and denied the legitimacy of any letters of marque issued by its government. Union President Abraham Lincoln declared all medicines to the South to be contraband, and that any captured Confederate privateers were to be hanged as pirates. Ultimately, no one was hanged for privateering because the Confederate government threatened to retaliate against prisoners of war.
Initially, Confederate privateers operated primarily from New Orleans, but activity was soon concentrated in the Atlantic as the Union Navy began expanding its operations. Throughout the war, Confederate privateers successfully harassed Union merchant ships, sank several warships, and harmed the Northern economy.
One of the more well-known ships was CSS Virginia (formerly known as "USS Merrimack"), a Union ironclad(1855). In 1862 she fought USS Monitor in the Battle of Hampton Roads, an event that came to symbolize the end of the dominance of large wooden sailing warships.
The Confederates also constructed submarines, among the few submarines to have existed since the Turtle of the American Revolutionary War. The Pioneer and the Bayou St. John Confederate Submarine did not see action, but the Hunley became notable as the first submarine to sink a ship in a wartime engagement. (She sank a few minutes after the engagement from unknown causes.)
Confederate raiders were also used to disrupt Union merchant shipping, the most famous of them being the CSS Alabama, a ship made in Britain.
The CSS Shenandoah fired the last shot of the American Civil War in late June 1865, and finally surrendered in early November 1865.
There was a Revolutionary War-era frigate known as USS Confederacy, unrelated to the CSN. There was however a CSS United States, the name of the USS United States in 1861–1862, when she was captured and used by the CSN.