The first ironclad warships were the "turtle ships" of Korea, first mentioned in records from 1413.

The first use of steam-powered ironclads in combat was during the Civil War in October 1861. The CSS Manassas, was an ironclad ram used in combat against the U.S. Navy and proved effective until Northern ships learned to take advantage of its weak armor.

The first engagement of two ironclads was during the Battle of Hampton Roads, in 1862. The Confederate ironclad CSS Virginia and its Union counterpart, USS Monitor, became legendary, and helped to usher in a new age of armored warships. The Virginia was built from the remains of a U.S. ship called the Merrimack.

Among the types of ironclads were monitors, protected cruisers, armored cruisers and armored gunboats.

Combined with steam engine propellor propulsion, the ironclad warship could outfight even the most powerful "three decker."

The age of the ironclad came to an end around 1890, as steel-hulled battleships were developed.

During the Civil War, the North was the first to utilize a submarine. The French Alligator was the first navy submarine, the first to feature an air filtration system, and the first to allow a diver to exit to plant mines on enemy ships. Initially powered by oars, it was eventually converted to a hand-cranked screw propeller. The Alligator was 47 feet long and about 4 feet in diameter with a crew of 20. The sub was lost in a storm in 1863 while under tow to its first combat mission.

The first Confederate submarine was the 30-foot long Pioneer, which was never used in combat. The Confederacy had several other human-powered submarines including the CSS Hunley. The Hunley was used for attacking the Northern ships, which were blockading the South's seaports.

The submarine had no air supply except what was contained inside the main compartment. On two occasions, the sub sank and the crew drowned. In 1864 the Hunley sank the USS Housatonic. This was the first time a submarine successfully sank another ship, but it sank right after that. Submarines did not have a major impact on the outcome of the Civil War.

There were several major naval battles worth noting:

• The Battle of Aquia Creek
• The battle of Island Number Ten
• The Battle of Cockpit Point
• The Battle of Drewry's Bluff
• The Battle of Fort Hindman
• The Battle of Hampton Roads (The first battle between two ironclads)
• The Battle of Memphis
• The Battle of Tampa
• The Battle of Sewell's Point
• The Second Battle of Sabine's Pass
• The Battle of Mobile Bay

The last shot of the Civil War was fired by the CSS Shenandoah on June 22, 1865.