She performed convoy escort duties in the Indian Ocean between Colombo and Bombay before returning to the United Kingdom, calling at The Cape and Sierra Leone.

To achieve the higher speed while keeping displacement from growing, White was forced to reduce the ships' armour protection significantly, effectively making the ships enlarged and improved versions of the Canopus-class battleships of 1896, rather than derivatives of the more powerful Majestic, Formidable, and London series of first-class battleships.

The Duncans proved to be disappointments in service, owing to their reduced defensive characteristics, though they were still markedly superior to the Peresvets they had been built to counter.

The Duncan-class ships were powered by a pair of 4-cylinder triple-expansion engines that drove two screws, with steam provided by twenty-four Belleville boilers.

She transferred her flag in April 1907,[6] was reduced to a nucleus crew,[7] and entered the commissioned reserve to begin a refit at Portsmouth Dockyard.

[6] In July 1908, Exmouth visited Canada during the Quebec Tercentenary, in company with her sister ships Albemarle, Duncan, and Russell.

Upon completion of her refit, Exmouth recommissioned on 1 July 1913 at Devonport Dockyard with a nucleus crew to serve in the commissioned reserve with the 6th Battle Squadron, Second Fleet.

[6] When the First World War began in August 1914, plans originally called for Exmouth and the battleships Agamemnon, Albemarle, Cornwallis, Duncan, Russell, and Vengeance to combine in the 6th Battle Squadron and serve in the Channel Fleet, where the squadron was to patrol the English Channel and cover the movement of the British Expeditionary Force to France.

Exmouth, Russel, and Albemarle were the only ships in a condition to immediately join Jellicoe, so they left without the rest of the squadron on 5 August.

[11] When the Grand Fleet dreadnought battleship Audacious struck a mine north of Ireland on 27 October, Exmouth, which was moored in Lough Swilly, was sent to tow her to safety.

However, due a lack of antisubmarine defenses at Dover,[6] particularly after the harbour's anti-submarine boom was swept away in a gale,[16] the squadron returned to Portland on 19 November 1914.

Exmouth and Russell bombarded Zeebrugge, which was used by German submarines on passage from their base at Bruges, on 23 November 1914,[6][17] The two ships left Portland on 21 November accompanied by eight destroyers, a group of trawlers, and a pair of airships to observe the fall of shot, though the airships failed to arrive in time for the operation.

She steamed to the Mediterranean with the battleship Venerable; the British hoped to take advantage of the experience both ships' crews had gained in bombarding coastal positions in Belgium.

[7][19] On 4 June, Exmouth, the battleship Swiftsure, and the protected cruiser Talbot went to Cape Helles to support an Allied attack on the Turkish-held heights at Achi Baba.

Reports of enemy submarines in the area forced the ships to steam in circles to avoid being targeted, which reduced their accuracy.

Exmouth participated in the seizure of the Greek fleet at Salamis and landed Royal Marines at Athens on 1 December 1916.

[22] Exmouth transferred to the East Indies Station in March 1917, where she performed convoy escort duties in the Indian Ocean between Colombo and Bombay.

In June 1917, she ended this service to return to the United Kingdom, calling at Zanzibar, The Cape and Sierra Leone during the voyage.