Ironclads

Ironclads are warships protected by iron or steel armor that emerged in the mid-19th century, marking a transition from wooden sailing ships to armored steam-powered vessels. They combined heavy wrought-iron or later steel armor with steam propulsion, and often retained a small sail plan for auxiliary power. The concept originated in the 1850s and 1860s as naval powers sought to counter rifled artillery and explosive shells with protection and modern guns.

Designs varied from casemate ironclads with armored sides to turreted ships carrying rotating gun turrets. They typically used steam engines with screw propulsion and carried large-caliber guns, sometimes arranged in turrets or casemates. Armor schemes centered on belt armor near the waterline and protective decks, magazines, and batteries. The era produced several defining ships, such as the U.S. Monitor and CSS Virginia (Merrimack), whose 1862 engagement at Hampton Roads demonstrated the potential of armored ships; and the British HMS Warrior and the French Gloire, which showcased practical ocean-going ironclad designs.

Ironclads rapidly evolved and were soon outpaced by stronger steel hulls and more advanced propulsion and armament. By the late 19th century the term ironclad gave way to steel-hulled battleships, and the era contributed to a broader shift in naval power and ship design that culminated in the dreadnought era of the early 20th century.