The Orion-class battleships were a group of four dreadnought battleships built for the Royal Navy (RN) in the early 1910s. The first battleships built for the RN, since the 1890s Royal Sovereign-class, 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. and were sold for scrap in 1922 while 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. 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.
Background and design The initial 1909–1910 Naval Programme included two dreadnoughts and a battlecruiser, but was later increased to six dreadnoughts and two battlecruisers as a result of public pressure on the government due to the Anglo-German naval arms race. The original pair of battleships became the and were improved versions of the preceding battleship, . A third dreadnought was added to the programme around April 1909 that was to be armed with more powerful weapons than the guns used in the earlier dreadnoughts. Three more ships of this class, as well as another battlecruiser, were part of the contingency programme authorized in August.Friedman 2015, p. 111
Unlike all of the previous dreadnoughts, which had been incremental improvements of the original design of 1906, constrained by cost and size limits, the Orion class were almost a "clean-slate" design driven by the need to accommodate the larger guns and additional armour. The guns were positioned all on the centreline of the hull in superfiring gun turrets, an arrangement first used in HMS Neptune for the aft main turrets. The idea had been pioneered by the United States Navy in their , but the RN was slow to adopt the concept, concerned about the effects of muzzle blast on the gunlayers in the open sighting hoods in the roofs of the lower turrets.Parkes, pp. 510, 525–526
One of the few things retained from earlier ships was the position of the tripod foremast with its spotting top behind the forward funnel to allow the vertical leg to be used to support the boat-handling derrick. This all but guaranteed that the hot funnel gases could render the spotting top uninhabitable at times, but the Board of Admiralty insisted on it for all the ships of the 1909–1910 Programme.Brooks 1995, pp. 42–44; Friedman 2015, p. 114 David K. Brown, naval architect and historian, commented on the whole fiasco: "It is amazing that it took so long to attain a satisfactory arrangement, which was caused by the Director of Naval Ordnance (DNO)'s insistence on sighting hoods in the roofs of turrets and Jellicoe's obsession with boat-handling arrangements. These unsatisfactory layouts reduced firepower, prejudiced torpedo protection and probably added to cost. As DNO and then as Controller, Jellicoe must accept much of the blame for the unsatisfactory layout of the earlier ships."Brown, pp. 41–42
Description
The Orion-class ships had an overall length of , a beam of , a normal draught of and a deep draught of . They displaced at normal load and at deep load. Their crew numbered 738 officers and ratings upon completion and 1,107 in 1917.Burt, p. 136
The ships retained the three engine-room layout of the Colossus-class design. They were powered by two sets of Parsons direct-drive steam turbines. The outer propeller shafts were coupled to the high-pressure turbines in the outer engine rooms and these exhausted into low-pressure turbines in the centre engine room which drove the inner shafts. The turbines used steam provided by 18 water-tube boilers. They were rated at and were intended to give the battleships a maximum speed of . During their sea trials, the Orions exceeded their designed speed and horsepower. They carried a maximum of of coal and an additional of fuel oil that was sprayed on the coal to increase its burn rate. This gave them a range of at a cruising speed of .Burt, pp. 136, 140
Armament These ships were the first to carry the new breech-loading (BL) 13.5-inch Mark V gun. This gun was developed as the RN believed that the preceding 12-inch Mark XI gun could not be further developed and that a new gun of an increased bore was needed to deal with the longer ranges at which combat was expected to occur and the need for greater penetration and destructive effect. The Mark V gun had a muzzle velocity about lower than the Mark XI gun, which greatly reduced the wear in the barrel. Despite the reduction in velocity, the gun's range was about greater because the much heavier 13.5-inch shell retained its velocity longer than the lighter and smaller 12-inch shell.Burt, p. 132; Friedman 2011, pp. 49–51, 62–63
The Orion class was equipped with ten 45-calibre Mark V guns in five hydraulically powered, centreline, twin-gun turrets, designated 'A', 'B', 'Q', 'X' and 'Y' from front to rear. The guns had a maximum elevation of +20° which gave them a range of . Their gunsights, however, were limited to +15° until super-elevating prisms were installed by 1916 to allow full elevation. They fired projectiles, some more than those of the 12-inch Mark XI, at a muzzle velocity of at a rate of two rounds per minute.Friedman 2011, pp. 49–52 The ships carried 80–100 shells per gun.
Their secondary armament consisted of sixteen 50-calibre BL four-inch (102 mm) Mark VII guns. Four of these guns were in exposed mounts on the shelter deck and the remaining guns were enclosed in unshielded single mounts in the superstructure.Parkes, p. 523 The guns had a maximum elevation of +15° which gave them a range of . They fired projectiles at a muzzle velocity of .Friedman 2011, pp. 97–98 They were provided with 150 rounds per gun. Four 3-pounder () saluting guns were also carried. The ships were equipped with three 21-inch submerged torpedo tubes, one on each broadside and another in the stern, for which 20 torpedoes were provided.
Fire control
The control positions for the main armament were located in the spotting tops at the head of the fore and mainmasts. Data from a Barr and Stroud coincidence rangefinder, located at each control position, was input into a Dumaresq mechanical computer and electrically transmitted to Vickers range clocks located in the transmitting station located beneath each position on the main deck, where it was converted into range and deflection data for use by the guns. The target's data was also graphically recorded on a plotting table to assist the gunnery officer in predicting the movement of the target. The turrets, transmitting stations, and control positions could be connected in almost any combination.Brooks 1995, pp. 40–41 As a backup, two turrets in each ship could take over if necessary.Brooks 2005, p. 61
was the second British dreadnought to be built with a gunnery director, albeit a prototype.Brooks 1996, pp. 163–165 This was mounted on the foremast, underneath the spotting top and electrically provided data to the turrets via pointers, which the turret crew were to follow. The director layer fired the guns simultaneously which aided in spotting the shell splashes and minimised the effects of the roll on the dispersion of the shells.Brooks 2005, p. 48 While the exact dates of installation are uncertain, all four ships were equipped with a director by December 1915.Brooks 1996, p. 168
Additional nine-foot rangefinders, protected by armoured hoods, were added for each gun turret in late 1914. Furthermore, the ships were fitted with Mark II or III Dreyer Fire-control Tables, in early 1914, in each transmission station. It combined the functions of the Dumaresq and the range clock.Brooks 2005, pp. 157–158, 175
Armour
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 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 below where the waterline and thinned to at its bottom edge. Above this was a strake of 8-inch armour. The forward oblique 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 thick above the main deck that thinned to below it. The gun turrets had faces and 8-inch sides with 3-inch roofs.Burt, pp. 134, 136, 139
The four armoured decks ranged in thickness from 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 . The boiler uptakes were protected by armour plates.Burt, pp. 136, 139
Modifications received a small rangefinder on the roof of 'B' turret in 1914; the other ships may also have had one installed. That same year the shelter-deck guns of the sisters were enclosed in casemates. By October 1914, a pair of QF anti-aircraft (AA) guns were installed aboard each ship. Additional deck armour was added after the Battle of Jutland in May 1916. Around the same time, three or four 4-inch guns were removed from the aft superstructure. By April 1917, the ships had exchanged a 4-inch AA gun for one of the 3-inch guns. One or two flying-off platforms were fitted aboard each ship during 1917–1918; these were mounted on turret roofs and extended onto the gun barrels. had them on 'B' and 'Q' turrets, Conqueror and Thunderer on 'B' and 'X' turrets and had one on 'B'. A high-angle rangefinder was fitted in the forward superstructure by 1921. Thunderer had her secondary armament reduced to eight guns during her February–May 1921 conversion into a training ship.Burt, pp. 140, 142; Friedman 2015, pp. 123, 198–199, 205
Ships + Construction dataShipBuilderLaid downLaunchedPreston, p. 28CommissionedCost (including armament) according toBurtParkesHM Dockyard, Portsmouth29 November 190920 August 19102 January 1912£1,855,917£1,918,773Armstrong Whitworth, Elswick1 April 191030 March 191127 April 1912£1,888,736£1,886,912William Beardmore, Dalmuir5 April 19101 May 19111 December 1912£1,891,164£1,860,648Thames Ironworks, London13 April 19101 February 191115 June 1912£1,892,823£1,885,145
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