How did iron and steel armour change warship design in the 19th century?

The introduction of iron and steel armour in the 19th century fundamentally transformed warship design, marking the transition from wooden, sail-driven vessels to the modern battleship.12

The development of powerful shell guns necessitated protective plating, leading to the creation of ironclad warships. Early designs, such as the French Gloire and the British Warrior, utilized wrought-iron plates backed by thick wood to resist enemy fire. As naval artillery grew more sophisticated, armour technology evolved:13
* Compound Armour: Combined steel’s surface hardness with iron’s resiliency.4
* Steel Armour: Innovations like oil-tempering and the addition of nickel and chromium improved resistance.4
* Face-Hardening: Processes such as the Harvey and Krupp methods were developed to counter armour-piercing shells, becoming the standard for world navies.4

These advancements demanded stronger, all-metal hulls, which in turn supported the installation of heavy, rifled, breech-loaded guns. Furthermore, the weight of this armour and the requirements of steam power shifted design focus toward maneuverability and specialized configurations, such as the revolving gun turret seen on the Monitor. Ultimately, these innovations rendered wooden navies obsolete, establishing the battleship as the dominant capital ship until the rise of the aircraft carrier.51632