Armor - Iron Plating on the USS Cairo
The starboard (right) side of the gunboat shows gun ports number 3 and 4. The iron plating was mounted as part of the sloping casemate that enclosed the gun deck. The 2-1/2 inch thick charcoal plate iron was originally backed by a two foot thickness of white oak timbers. Without the wood to absorb the shock of shot and shell hitting the iron, the metal would have shattered like glass.