Central battery ironclad

The central battery ship, also known as a centre battery ship in the United Kingdom and as a casemate ship in European continental navies, was a development of the (high-freeboard) broadside ironclad of the 1860s, given a substantial boost due to the inspiration gained from the Battle of Hampton Roads, the very first battle between ironclads fought in 1862 during the American Civil War. One of the participants was the Confederate casemate ironclad CSS Virginia, essentially a central battery ship herself, albeit a low-freeboard one. The central battery ships had their main guns concentrated in the middle of the ship in an armoured citadel. The concentration of armament amidships meant the ship could be shorter and handier than a broadside type like previous warships. In this manner the design could maximize the thickness of armour in a limited area while still carrying a significant broadside. These ships meant the end of the armoured frigates with their full-length gun decks.

In the UK, the man behind the design was the newly appointed Chief Constructor of the Royal Navy, Edward James Reed. The previous Royal Navy ironclad designs, represented by HMS Warrior, had proven to be seaworthy, fast under power and sail, but their armour could be easily penetrated by more modern guns. The first central battery ship was HMS Bellerophon of 1865. Great Britain built a total of 18 central battery ships before turrets became common on high-freeboard ships in the 1880s.

...
Wikipedia