Orion-class battleship

Thunderer at anchor, shortly after completion in 1912
Class overview
Name	Orion-class battleship
Operators	Royal Navy
Preceded by	Colossus class
Succeeded by	King George V class
Built	1909–1912
In commission	1912–1922
Completed	4
Scrapped	4
General characteristics (as built)
Type	Dreadnought battleship
Displacement	21,922 long tons (22,274 t) (normal)
Length	581 ft (177.1 m) (o/a)
Beam	88 ft 6 in (27.0 m)
Draught	27 ft 6 in (8.4 m)
Installed power	27,000 shp (20,000 kW) 18 × water-tube boilers
Propulsion	4 × shafts; 2 × steam turbine sets
Speed	21 knots (39 km/h; 24 mph)
Range	6,730 nmi (12,460 km; 7,740 mi) at 10 knots (19 km/h; 12 mph)
Complement	738–1,107 (1917)
Armament	5 × twin 13.5-inch (343 mm) guns 16 × single 4-inch (102 mm) guns 3 × 21-inch (533 mm) torpedo tubes
Armour	Belt: 8–12 in (203–305 mm) Deck: 1–4 in (25–102 mm) Turrets: 11 in (280 mm) Barbettes: 4–10 in (102–254 mm) Bulkheads: 6 and 10 in (152 and 254 mm) Conning tower: 11 in (280 mm)

The Orion-class battleships were a group of four dreadnought battleships built for the Royal Navy (RN) in the early 1910s. The first 13.5-inch-gunned (343 mm) 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. While being towed to the scrapyard, the ship ran aground; Thunderer was refloated and subsequently broken up.