page_title: Orion-class battleship
section_title: Armour
hierarchical_section_title: Orion-class battleship / Description / Armour
caption_attribution_description: English: The battleship HMS Orion and the destroyer HMS Musketeer, 1918
context_page_description: The Orion-class battleships were a group of four dreadnought battleships built for the Royal Navy in the early 1910s. The first 13.5-inch-gunned battleships built for the RN, they were much larger than the preceding British dreadnoughts and were sometimes termed "super-dreadnoughts". The sister ships spent most of their careers assigned to the 2nd Battle Squadron of the Home and Grand Fleets, sometimes serving as flagships. Aside from participating in the failed attempt to intercept the German ships that had bombarded Scarborough, Hartlepool and Whitby in late 1914, the Battle of Jutland in May 1916 and the inconclusive Action of 19 August, their service during World War I generally consisted of routine patrols and training in the North Sea.
  The Orions were deemed obsolete by the end of the war in 1918 and were reduced to reserve the following year. Orion and Conqueror were sold for scrap in 1922 while Monarch was hulked for use as a stationary training ship. In late 1923, she was converted into a target ship and was sunk in early 1925. Thunderer served the longest, acting as a training ship from 1921 until she, too, was sold for scrap in late 1926.
context_section_description: The Orion class had a waterline belt of Krupp cemented armour that was 12 inches thick between the fore and rear barbettes that was reduced to 2.5–6 inches (64–152 mm) outside the central armoured citadel, but did not reach the bow or stern. The belt covered the side of the hull from the middle deck to 3 feet 4 inches (1.0 m) below where the waterline and thinned to 8 inches (203 mm) at its bottom edge. Above this was a strake of 8-inch armour. The forward oblique 6-inch (152 mm) bulkheads connected the waterline and upper armour belts to the 'A' barbette. Similarly the aft bulkhead connected the armour belts to 'Y' barbette, although it was 8 inches thick. The exposed faces of the barbettes were protected by armour 10 inches (254 mm) thick above the main deck that thinned to 3–7 inches (76–178 mm) below it. The gun turrets had 11-inch (279 mm) faces and 8-inch sides with 3-inch roofs.
  The four armoured decks ranged in thickness from 1 to 4 inches (25 to 102 mm) with the greater thicknesses outside the central armoured citadel. The front and sides of the conning tower were protected by 11-inch plates, although the roof was 3 inches thick. The spotting tower behind and above the conning tower had 6-inch sides and the torpedo-control tower aft had 3-inch sides and a 2-inch roof. Like the Colossus-class ships, the Orions eliminated the anti-torpedo bulkheads that protected the engine and boiler rooms, reverting to the scheme in the older dreadnoughts that placed them only outboard of the magazines with thicknesses ranging from 1 to 1.75 inches (25 to 44 mm). The boiler uptakes were protected by 1–1.5-inch (25–38 mm) armour plates.
caption: Orion and the destroyer Musketeer under way, 1918
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