Aetna-class ironclad floating battery
The Aetna-class ironclad floating batteries were built during the Crimean War for the attack of Russian coastal fortifications. Britain and France each laid down five of these coastal attack vessels in 1854. The French used three of their batteries in 1855 against the defences at Kinburn on the Black Sea, where they were effective against Russian shore defences. The British plan to use theirs in the Baltic Sea against Kronstadt in 1856 was influential in causing the Russians to sue for peace. The development of such iron-armoured batteries was a step towards the development of ironclad warships. "These armoured batteries were among the most revolutionary ships ever built and provided British and French designers with the germ of the battleship." One of the British batteries, Trusty, was used for trials in 1861 with a prototype rotating turret, based on Captain Cowper Phipps Coles' designs. Genesis Emperor Napoleon III initiated the design of armoured steam-powered batteries for the French Navy. The original idea was to protect the sides with boxes of cannonballs, but the British engineer Thomas Lloyd suggested using thick wrought iron plates instead. Trials at Vincennes showed that Lloyd's idea was more effective, so it was adopted. Napoleon wanted