HMS Theseus saw service as tender to HMS Cambridge from 1905 to 1913 and then joined the Queenstown Training Squadron in February 1913. Theseus joined the 10th Cruiser Squadron during 1914-1915 after which she was rearmed and bulges added for Dardanelles service. She returned from service in the Mediterranean in 1916 and was sent to the White Sea. In 1918 she was stationed as a depot ship in the Aegean and later in 1919 in the Black Sea, returning home in 1920. She was sold and scrapped in 1921.
Displacement: 7,700 tons. Horse power: 12,000. Length 360ft. Beam: 60' 8". Draught: 23' 9". Armament: two 22 ton guns. ( protected by steel shields) Speed:19.7 knots.
