In October 1914, the ship was patrolling off the coast of Norway and almost intercepted the armed merchant cruiser on several occasions. During a sweep into the Heligoland Bight on 26 November, she was unsuccessfully bombed by a German aircraft. She began a refit shortly afterwards that lasted until 24 January 1915. "Shannon" was present in Cromarty Firth when the armoured cruiser 's magazine exploded on 30 December 1915 and her crew attempted to rescue survivors from "Natal". The ship received a QF 12-pounder (three-inch) 12-cwt anti-aircraft (AA) gun and a QF 3-pounder (47 mm) AA gun in 1915–16. The 12-pounder gun was mounted on the aft superstructure and the 3-pounder on the quarterdeck at the extreme rear. Sometime afterwards, a fire-control system was installed with a director mounted on a platform fitted to the foremast.