HMS "Cardiff" was a C-class light cruiser built for the Royal Navy during World War I. She was one of the five ships of the "Ceres" sub-class and spent most of her career as a flagship. Assigned to the Grand Fleet during the war, the ship participated in the Second Battle of Heligoland Bight in late 1917. "Cardiff" was briefly deployed to the Baltic in late 1918 supporting anti-Bolshevik forces during the British campaign in the Baltic during the Russian Civil War.