Ironclads were originally wooden vessels protected by iron plates; they were used at the siege of Gibraltar in 1782; the French had them in the Crimean War, and in 1858 built four iron-plated line-of-battle ships; in 1860 England built the Warrior, an iron steam battleship with 4½-inch plates; since then new types have succeeded each other very quickly; the modern ironclad is built of steel and armed with steel plates sometimes 2 feet thick; the term is now loosely applied to all armoured vessels, whether battleships, or cruisers, or gunboats, and whether of iron or steel.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
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