On the outbreak of the First World War, "Grafton" was part of the 10th Cruiser Squadron, which was employed in enforcing the naval blockade of Germany. In December 1914, with the "Edgar" class having proved unsuitable for blockade work in the North Sea, "Grafton" was withdrawn from active service, with her two 9.2 inch guns removed to arm the monitors and . It was decided to refit four ships of the "Edgar" class, including "Grafton", for shore bombardment work for the planned operations in the Dardanelles. Two 6 inch guns replaced the 9.2 inch weapons that had been removed to arm the "M15"-class ships, while anti-torpedo bulges were fitted. These reduced the ship's speed by .