HMS Royal Oak was one of five s built for the Royal Navy during the First World War. Completed in 1916, the ship first saw combat at the Battle of Jutland as part of the Grand Fleet. In peacetime, she served in the Atlantic, Home and Mediterranean fleets, more than once coming under accidental attack. Royal Oak drew worldwide attention in 1928 when her senior officers were controversially court-martialled, an event that brought considerable embarrassment to what was then the world's largest navy. Attempts to modernise Royal Oak throughout her 25-year career could not fix her fundamental lack of speed and, by the start of the Second World War, she was no longer suitable for front-line duty.

On 14 October 1939, Royal Oak was anchored at Scapa Flow in Orkney, Scotland, when she was torpedoed by the German submarine . Of Royal Oaks complement of 1,234 men and boys, 835 were killed that night or died later of their wounds. The loss of the outdated ship—the first of five Royal Navy battleships and battlecruisers sunk in the Second World War—did little to affect the numerical superiority enjoyed by the British navy and its Allies, but it had a considerable effect on wartime morale. The raid made an immediate celebrity and war hero of the U-boat commander, Günther Prien, who became the first German submarine officer to be awarded the Knight's Cross of the Iron Cross. Before the sinking of Royal Oak, the Royal Navy had considered the naval base at Scapa Flow impregnable to submarine attack, but U-47s raid demonstrated that the German navy was capable of bringing the war to British home waters. The shock resulted in rapid changes to dockland security and the construction of the Churchill Barriers around Scapa Flow, with the added advantage of being topped by roads running between the islands.

The wreck of Royal Oak, a designated war grave, lies almost upside down in of water with her hull beneath the surface. In an annual ceremony marking the loss of the ship, Royal Navy divers place a White Ensign underwater at her stern. Unauthorised divers are prohibited from approaching the wreck under the Protection of Military Remains Act 1986.

Design and description

The Revenge-class ships were designed as slightly smaller, slower, and more heavily protected versions of the preceding s. As an economy measure they were intended to revert to the previous practice of using both fuel oil and coal, but First Sea Lord Jackie Fisher rescinded the decision for coal in October 1914. While under construction the ships were redesigned to employ oil-fired boilers that increased the power of the engines by over the original specification.

Royal Oak had a length overall of , a beam of and a deep draught of . She had a designed displacement of and displaced at deep load. She was powered by two sets of Parsons steam turbines, each driving two shafts, using steam from 18 Yarrow boilers. The turbines were rated at 40,000 shaft horsepower (30,000 kW) and intended to reach a maximum speed of . During her sea trials on 22 May 1916, the ship reached a top speed of only from . She had a range of at a cruising speed of . Her crew numbered 909 officers and ratings in 1916.

The Revenge class was equipped with eight breech-loading (BL) Mk I guns in four twin gun turrets, in two superfiring pairs fore and aft of the superstructure, designated 'A', 'B', 'X', and 'Y' from front to rear. Twelve of the fourteen BL Mk XII guns were mounted in casemates along the broadside of the vessel amidships; the remaining pair were mounted on the shelter deck and were protected by gun shields. Their anti-aircraft (AA) armament consisted of two quick-firing (QF) 20 cwt Mk I"Cwt" is the abbreviation for hundredweight, 20 cwt referring to the weight of the gun. guns. The ships were fitted with four submerged 21-inch (533 mm) torpedo tubes, two on each broadside.

Royal Oak was completed with two fire-control directors fitted with rangefinders. One was mounted above the conning tower, protected by an armoured hood, and the other was in the spotting top above the tripod foremast. Each turret was also fitted with a 15-foot rangefinder. The main armament could also be controlled by 'X' turret. The secondary armament was primarily controlled by directors mounted on each side of the compass platform on the foremast once they were fitted in March 1917. A torpedo-control director with a 15-foot rangefinder was mounted at the aft end of the superstructure.

The ship's waterline belt consisted of Krupp cemented armour (KC) that was thick between 'A' and 'Y' barbettes and thinned to towards the ship's ends, but did not reach either the bow or the stern. Above this was a strake of armour 6 inches thick that extended between 'A' and 'X' barbettes. Transverse bulkheads 4 to 6 inches thick ran at an angle from the ends of the thickest part of the waterline belt to 'A' and 'Y' barbettes. The gun turrets were protected by of KC armour, except for the turret roofs which were thick. The barbettes ranged in thickness from above the upper deck, but were only 4 to 6 inches thick below it. The Revenge-class ships had multiple armoured decks that ranged from in thickness. The main conning tower had 13 inches of armour on the sides with a 3-inch roof. The torpedo director in the rear superstructure had 6 inches of armour protecting it. After the Battle of Jutland, 1 inch of high-tensile steel was added to the main deck over the magazines and additional anti-flash equipment was installed in the magazines.

The ship was fitted with flying-off platforms, mounted on the roofs of 'B' and 'X' turrets, in 1918; from which fighters and reconnaissance aircraft could launch. In 1934 the platforms were removed from the turrets and a catapult was installed on the roof of 'X' turret, along with a crane to recover a seaplane.

Major alterations

Royal Oak was extensively refitted between 1922 and 1924, when her anti-aircraft defences were upgraded by replacing the original three-inch AA guns with a pair of QF Mk V AA guns. A rangefinder was fitted in 'B' turret and a simple high-angle rangefinder was added above the bridge. Underwater protection improved by the addition of anti-torpedo bulges. They were designed to reduce the effect of torpedo detonations and improve stability at the cost of widening the ship's beam by over . They increased her beam to , reduced her draught to , increased her metacentric height to at deep load, and all the changes to her equipment increased her crew to a total of 1,188. Despite the bulges she was able to reach a speed of . A brief refit in early 1927 saw the addition of two more four-inch AA guns and the removal of the six-inch guns from the shelter deck. About 1931, a High-Angle Control System (HACS) Mk I director replaced the high-angle rangefinder on the spotting top. Two years later, the aft pair of torpedo tubes were removed.

The ship received a final refit between 1934 and 1936, when her deck armour was increased to over the magazines and to over the engine rooms. In addition to a general modernisation of the ship's systems, her anti-aircraft defences were strengthened by replacing the single mounts of the AA guns with twin mounts for the QF 4-inch Mark XVI gun and adding a pair of octuple mounts for two-pounder Mk VIII "pom-pom" guns to sponsons abreast the funnel. Two positions for "pom-pom" anti-aircraft directors were added on new platforms abreast and below the fire-control director in the spotting top. A HACS Mk III director replaced the Mk I in the spotting top and another replaced the torpedo director aft. A pair of quadruple mounts for Vickers .50 machine guns were added abreast the conning tower. The mainmast was reconstructed as a tripod to support the weight of a radio-direction finding office and a second High-Angle Control Station. The forward pair of submerged torpedo tubes were removed and four experimental 21-inch torpedo tubes were added above water forward of 'A' turret.

Construction and service Royal Oak was laid down at Devonport Royal Dockyard on 15 January 1914. She was launched on 17 November, and after fitting-out was commissioned on 1 May 1916 at a final cost of £2,468,269. Named after the Royal Oak in which Charles II hid following his defeat at the 1651 Battle of Worcester, she was the eighth vessel to bear the name Royal Oak, replacing a pre-dreadnought scrapped in 1914. Upon completion Royal Oak was assigned to the Third Division of the Fourth Battle Squadron of the Grand Fleet, under the command of Captain Crawford Maclachlan.

First World War Battle of Jutland

In an attempt to lure out and destroy a portion of the Grand Fleet, the German High Seas Fleet, composed of 16 dreadnoughts, 6 pre-dreadnoughts, 6 light cruisers, and 31 torpedo boats, departed the Jade early on the morning of 31 May. The fleet sailed in concert with Rear-Admiral Franz von Hipper's five battlecruisers and supporting cruisers and torpedo boats. The Royal Navy's Room 40 had intercepted and decrypted German radio traffic containing plans of the operation. The Admiralty ordered Admiral John Jellicoe, commander of the Grand Fleettotalling 28 dreadnoughts and 9 battlecruisersto sortie the night before to cut off and destroy the High Seas Fleet. The initial action was fought primarily by the British and German battlecruiser formations in the afternoon, but by 18:00 the Grand Fleet approached the scene. Fifteen minutes later, Jellicoe gave the order to turn and deploy the fleet for action.

The German cruiser had become disabled by British shellfire, and both sides concentrated in the area, the Germans trying to protect their cruiser and the British attempting to sink her. At 18:29, Royal Oak opened fire on the German cruiser, firing four salvoes from her main guns in quick succession, along with her secondary battery. She scored a hit on Wiesbaden aft with her third salvo. In return, Royal Oak was straddled by a German salvo at 18:33 but was undamaged. German torpedo boats attempted to reach Wiesbaden shortly after 19:00, and at 19:07, Royal Oaks secondary guns opened fire on them, believing they were instead trying to launch a torpedo attack. By 19:15, Royal Oaks gunners had observed the German battlecruiser squadron and opened fire at the leading vessel, . The gunners overestimated the range initially, but by 19:20 had found the correct distance and scored a pair of hits aft, which did not inflict serious damage. Derfflinger then disappeared in the haze, so Royal Oak shifted fire to the next battlecruiser, . She scored a hit at 19:27 before Seydlitz too was lost in the mist.

While Royal Oak was attacking the battlecruisers, a German torpedo boat flotilla launched an attack on the British battleline. Royal Oaks secondary guns were the first to open fire, at 19:16, followed quickly by the rest of the British ships. Following the German destroyer attack, the High Seas Fleet disengaged, and Royal Oak and the rest of the Grand Fleet saw no further action in the battle. This was, in part, due to confusion aboard the fleet flagship over the exact location and course of the German fleet; without this information, Jellicoe could not bring his fleet to action. At 21:30, the Grand Fleet began to reorganise into its night-time cruising formation. Early on the morning of 1 June, the Grand Fleet combed the area, looking for damaged German ships, but after spending several hours searching, they found none. In the course of the battle, Royal Oak had fired 38 rounds from her main battery and 84 rounds from her secondary guns.

Later actions