Armorplate is a metal protective covering consisting usually, but not always, of several layers of differently heat-treated metals whose combined properties provide the best possible protection. Case-hardened body armor appeared as early as the 15th century; but it was not until the 19th century that armorplate was applied to ships, playing an important part in the Crimean War.

 

Since the nineteenth century, armorplate has been made either of several laminae, typically carbon steel with a backing of wrought iron, or as a single thick layer of metal. Modern armorplate is applied to land vehicles such as tanks as well as to sea-going craft.