On the night of 3/4 September 1917, "S18" was damaged in a British air raid on Zeebrugge. Later that year, "S18" was transferred to an escort flotilla, and on 17 November 1917, she was part of the escort for German battleships during the Second Battle of Heligoland Bight. and at the end of the war was still a member of the 1st half-flotilla of the 1st Escort Flotilla.