Iron Duke was therefore converted into a gunnery training ship; her armour and much of her armament was removed to render her unfit for combat.

She served in this capacity until the outbreak of the Second World War in September 1939, when she was moored in Scapa Flow as a harbour defence ship.

The four Iron Duke-class battleships were ordered in the 1911 building programme, and were an incremental improvement over the preceding King George V class.

Close-range defence against torpedo boats was provided by a secondary battery of twelve BL 6-inch Mk VII guns.

[3] On the evening of 22 November 1914, the Grand Fleet conducted a fruitless sweep in the southern half of the North Sea; Iron Duke stood with the main body in support of Vice Admiral David Beatty's 1st Battlecruiser Squadron.

[5] Iron Duke and most of the fleet initially remained in port during the German raid on Scarborough, Hartlepool and Whitby on 16 December 1914, though the 3rd Battle Squadron was sent to reinforce the British forces in the area.

[10] Upon returning from the operation, Iron Duke went to Invergordon for refit; while she was away, HMS Centurion acted as the temporary fleet flagship.

[26] Later in the month, Iron Duke took part in gunnery drills, and during them, conducted an experiment of sorts to determine the accuracy of the ship's gunners.

By the time the Grand Fleet approached the area on 26 March, the British and German forces had already disengaged and a severe gale threatened the light craft.

[31] On 21 April, the Grand Fleet conducted a demonstration off Horns Reef to distract the Germans while the Russian Navy relaid its defensive minefields in the Baltic Sea.

[32] The fleet returned to Scapa Flow on 24 April and refuelled before proceeding south in response to intelligence reports that the Germans were about to launch a raid on Lowestoft.

The fleet sailed in concert with Rear Admiral Franz von Hipper's five battlecruisers and supporting cruisers and torpedo boats.

[38] The initial action was fought primarily by the British and German battlecruiser formations in the afternoon,[39] but by 18:00, the Grand Fleet approached the scene.

[40] Fifteen minutes later, Iron Duke had closed to effective gunnery range—some 26,000 yards (24,000 m)—of the German fleet, and took the dreadnought SMS König under fire.

Iron Duke's first salvo fell short, but the next three were on target; the ship's gunner claimed at least six hits on the German battleship.

Iron Duke opened fire on the crippled cruiser and nearby destroyers with her secondary battery at 19:11 at a range of 9,000 to 10,000 yards (8,200 to 9,100 m).

[43] Shortly thereafter, the German destroyers attempted to launch a torpedo attack on the British line; Iron Duke began firing at 19:24.

The sinking of the destroyer SMS S35 is credited to a salvo from Iron Duke, but determining which ship fired which shells in the melee is difficult, according to naval historian John Campbell.

[46] 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.

British signals intelligence decrypted German wireless transmissions, allowing Jellicoe enough time to deploy the Grand Fleet in an attempt to engage in a decisive battle.

As a result, many ships in the Grand Fleet had additional armour installed; Iron Duke went into dock for this work in October.

[52] On 28 November 1916, while she was still in dry dock, Admiral Beatty replaced Jellicoe as the commander of the Grand Fleet; Iron Duke served as his flagship until January 1917, when he transferred to Queen Elizabeth.

[55] On 12 May, Iron Duke travelled from Constantinople to Smyrna, where she provided a landing party to occupy some of the city's outer forts.

[61] On 2 September 1922, Iron Duke was steaming to the Dalmatian coast for a training cruise, when she received news of the Greek defeat in Turkey.

Admiral Osmond Brock, the Mediterranean Fleet commander, ordered Iron Duke to proceed to Smyrna, where he expected disturbances.

[28] During the chaos, a number of refugees managed to come alongside Iron Duke in small boats, and were brought aboard the battleship.

[28] In November 1931, under the terms of the London Naval Treaty, Iron Duke was disarmed and converted into a gunnery training vessel.

[3] On 17 October 1939, four Junkers Ju 88 medium bombers attacked Scapa Flow, and damaged Iron Duke with several near misses.

[69] The ship's presence in Scapa Flow may have affected the Germans' plans during Operation Rheinübung, the Atlantic sortie of the battleship Bismarck in May 1941.

[3] Iron Duke remained in the Royal Navy inventory until March 1946, when she was sold for scrapping to Metal Industries, still beached in Scapa Flow.