Before the Civil War
The French ironclad, Gloire.
The Gloire
Development of Ironclad Warships Before the Civil War
Neither the Monitor nor the Virginia was the first ironclad war vessel on the seas. The concept of providing metallic armor to wooden vessels dates back to at least the 1592, when Korean Admiral Yi Sun-Sin led a fleet of armored Kohbudson, or "turtle ships," against an invading Japanese fleet. However, it was not until the mid-19th century that true ironclad vessels were tested and adopted by the world's navies.

Though the French navy experimented with Paixhans's guns, it was the Russians who first demonstrated their effectiveness. At the battle Sinope in 1853, Russian ships armed with Paixhans's new shell guns attacked a Turkish squadron. Using explosive shells, the Russians destroyed the entire Turkish flotilla. As Paixhans had predicted, the shells embedded themselves in the wooden planking of the Turkish ships, exploded, and ignited the wooden hulls. The vulnerability of wooden-hulled ships to the new shell guns was thus confirmed.

Two years later, ironclad vessels would also be tested in the Crimea. At the bombardment of the Russian forts at Kinburn in 1855, the French sent a small squadron of ironclad batteries against the land-based forts. The ironclads approached to within 100 yards of the enemy guns (a distance at which wooden ships would have been shot to splinters), and engaged the Russian forts. The French floating batteries proved to be nearly impervious to Russian fire, and succeeded in nearly leveling the fortifications.

In the aftermath of the fight at Kinburn, the durability of the ironclad batteries could no longer be ignored by the world's sea powers. In 1856, the British ordered the construction of three ironclad floating batteries. Named Erebus, Thunderbolt, and Terror, these ships were classed as armored batteries measuring 108 feet in length and 48 feet in width; each carried 16 guns. The ships were steam-powered and were able to cruise at five knots an hour.

The expansion of iron warship technology continued in 1858, when the French began building the first true ironclad oceangoing naval vessels. The first of these vessels was the Gloire, launched in 1859.

The Gloire was a wooden frigate of 5,600 tons whose hull was sheathed in plates of iron measuring from 4 1/3 to 4 2/3 inches in thickness. Two sister ships, the Normandie and the Invincible, were also constructed following the same plans. The fourth ironclad constructed by the French in this first generation of ironclads was the Couronne. The Couronne was unusual in her hull design, for she had a multi-layered iron and wood construction. The Couronne's outer hull was iron measuring 4 inches thick which covered a wooden hull of 4 inches of teak, laid over a framework of 1 1/2-inch-thick iron, over 11 inches of teak, covering a final inner hull of 3/4-inch iron. This layered hull design would prove to be the standard of French naval design until the introduction of steel hulls later in the 19th century.

Nervous about the advances of the French navy, England responded in 1860 with the construction of the Warrior. Considered the most powerful vessel of her time, the Warrior was a ship of 9,358 tons and carried 40 guns. Her hull was of iron and she was armored with 4 1/2 inches of iron over 18 inches of teak in the mid section of the ship. The Warrior could travel under either steam or sail and was capable of speeds up to 14 knots.

With the successful launching of the Warrior in 1860, the British pursued a program of construction of ironclad ships. By the outbreak of the American Civil War, the French and British fleets contained formidable ironclad ships, but the new naval technology remained untried in battle.