When the USS Monitor and CSS Virginia traded fire at Hampton Roads in 1862 and neither could pierce the other, centuries of wooden naval warfare ended. This episode traces how the ironclad emerged from three technologies: explosive shells such as the French Paixhans guns, steam power with the screw propeller, and metal armor. The Russian destruction of an Ottoman fleet at Sinop in 1853 proved wooden hulls could not survive shellfire. French floating batteries at Kinburn in 1855 showed iron could, and the wood-hulled Gloire of 1859 prompted Britain’s all-iron HMS Warrior, which reached over 14 knots by armoring only a central citadel.

After Austria’s flagship rammed and sank the Re d’Italia at Lissa in 1866, navies spent two decades fitting ships with underwater rams. Guns grew to 16 inches and 110 tons, firing once every 11 to 15 minutes, while armor moved from iron backed by teak to compound plate, Harvey steel and Krupp cemented steel. The episode covers John Ericsson’s Monitor, James Eads’s river ironclads, the Whitehead torpedo and France’s Jeune École, and how by the 1890s the ironclad became the pre-dreadnought battleship.

• Crews heated iron shot red-hot to set wooden enemy hulls on fire.
• The double-loaded muzzle-loader that burst aboard HMS Thunderer in 1879 pushed the Royal Navy toward the de Bange breech seal.
• Just under six inches of Krupp armor matched 15 inches of the old wrought iron.
• HMS Captain, combining a low freeboard with a full sailing rig, capsized in a gale and took designer Cowper Coles with her.
• H.G. Wells later used the term land ironclads for his fictional forerunners of the tank.