[1] The R-class differed by having geared rather than direct drive steam turbines, giving greater fuel efficiency, having a higher forecastle for better seakeeping and a larger and more robust bridge structure.

On the return journey, Tarpon struck a mine, badly damaging her stern, and had to be towed back to Dunkirk by Thruster.

[15][16] On 13 October, the Swedish barque Esmerelda, sailing for the Tyne with a load of pit-props, was sunk by the German submarine UB-58.

[17] While she served with the 13th Flotilla, Telemachus's minelaying duties mainly lay in the approaches to the Belgian ports rather than longer-ranged missions to the German Bight.

[19] On 15 May 1918, Telemachus, together with Abdiel, Tarpon, Venturous, Ariel, Ferrett and Sandfly were on their way to lay a minefield when they ran into thick fog.

[22][23] The 20th Flotilla, including Telemachus, was carrying another minelaying operation on the night of 2–3 August 1918 when the destroyer Vehement struck a mine, blowing off her bow.

Ariel quickly sank, and it proved impossible to salvage Vehement, which was scuttled by Telemachus and Vanquisher using gunfire and depth charges.

[26] Telemachus remained in use after the war as an experimental minelayer,[27] but was sold for scrap to Hughes Bolckow at Blyth on 26 July 1927.