The ship was used as a troop transport during World War I, surviving a June 1918 collision with H.M.S. Rival off Eddystone. In that collision, live depth charges released from Rival exploded under Kenilworth Castle's stern. 15 crew members were drowned and the ship was badly damaged. She returned to commercial service at war's end and was broken up in 1936.
Sources: Haws' Merchant Fleets; Kludas' Great Passenger Ships of the World; Mallett's The Union-Castle Line; Dunn's The Ships of the Union-Castle Line.