Here it may be observed that all the old wooden battleships were in a sense 'armoured.' Specially thick sides were employed for the specific purpose of keeping out projectiles, and it was rare for harm to be done save by shots that entered portholes. The Crimean floating batteries and the early broadside ironclads like the Gloire and Warrior were lineal descendants of the steam line of battleships that preceded them. They were built of iron instead of wood
French Floating Battery in the Crimean War.
and so had iron instead of wood armour (their armour being nothing but an increased thickness of the side, with wood backing).
The Monitor was not in any way a lineal evolution of past efforts. She was not a new idea in the matter of years, because so far back as the Crimean War, Ericsson, her inventor, had submitted plans of her to the French Emperor. At the same period Captain Cowper Coles of the British Navy actually produced a raft which carried on it a species of turret, and in 1860 he had lectured at the Royal United Service