HMS E9 was the first British submarine to sink an enemy warship in World War I.
On 13 September 1914, E9 torpedoed and sank the German light cruiser SMS Hela in the North Sea. The submarine was commanded by Lieutenant Commander Max Horton, who later became one of Britain’s leading submarine commanders.
E9 operated from Harwich and conducted patrols against German naval forces. After the sinking of Hela, Horton ordered the submarine’s crew to display the international signal for success when they returned, helping establish a tradition associated with British submarine operations.
E9 survived the war but was scuttled at Tallinn in 1918 to prevent its capture by advancing German forces. It should not be confused with HMS E11, another famous British E-class submarine celebrated for its Dardanelles campaigns.