She took part in numerous sorties into the northern North Sea to enforce the blockade of Germany, along with frequent training exercises and gunnery drills.

In 1931, she and Marlborough underwent a series of weapons tests that proved to be highly beneficial for future British battleship designs.

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.

The ship was commissioned into the Royal Navy's Grand Fleet under Admiral John Jellicoe in November 1914 for sea trials, three months after the outbreak of the First World War.

[16] From 2–5 November, Emperor of India participated in another fleet training operation west of Orkney[17] Another such cruise took place from 1–4 December.

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.

[21] 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.

[22] 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.

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.

[27] A series of minor modifications followed throughout 1917 and 1918; these included the installation of larger and additional searchlights to improve night combat capabilities, funnel caps to reduce smoke interference with the spotting tops, and rangefinder baffles that were intended to make it more difficult to estimate the range for enemy gunners.

In April 1918, the German fleet sortied in an attempt to catch one of the isolated British squadrons, though the convoy had already passed safely.

The Grand Fleet sortied too late to catch the retreating Germans, though the battlecruiser SMS Moltke was torpedoed and badly damaged by the submarine E42.

Reuter believed that the British intended to seize the German ships on 21 June 1919, which was the deadline for Germany to have signed the peace treaty.

[30] In 1919, Emperor of India was assigned to the Mediterranean Fleet,[31] as part of the 4th Battle Squadron, along with her three sisters and two King George V class battleships.

During this period, she served in the Black Sea during the Allied intervention in the Russian Civil War to support the Whites against the Red Bolsheviks.

Admiral Edward Hobart Seymour, the commander of British forces in the Black Sea, hoisted his flag aboard the ship on 14 April.

[33] On 26 March 1920, Emperor of India provided gunfire support to the evacuating White Russian forces outside Novorossiysk, along with the French armoured cruiser Waldeck-Rousseau.

[34] Shortly thereafter, Emperor of India came under fire from an armoured train, prompting the ship to leave the harbour, bound for Theodosia.

The tests were conducted on 10–11 June, with her sister Iron Duke, which hit Emperor of India with twelve 13.5-inch shells over the two days.

[42] Of particular importance was a shell that struck Emperor of India on the bottom edge of the main belt, which penetrated into one of the boiler rooms, where it caused tremendous damage.