[1][2] During the First World War, Grampus participated in the Dardanelles Campaign against the Ottoman Empire.

On 17 April 1915, in an attempt to break through the Dardanelles, the submarine HMS E15 ran aground under Kephaz Point.

She was fired on and disabled, her captain, Lieutenant Commander T. S. Brodie and several of her crew were killed; the remainder taken prisoner.

On 6 August, HMS Grampus landed 11th Battalion, The Manchester Regiment of the 11th (Northern) Division inside Suvla Bay, but on the wrong part of the beach.

The troops were ill-supplied and ran critically short of drinking water in the actions that followed; on 8 August, HMS Grampus cut one of her own water tanks loose and floated it ashore, which allowed the men who recovered it about a pint (0.5 litre) each.