On 9 August 1914, she spotted the , whose engines had failed as she lay stopped on the surface in heavy fog, off Fair Isle. The crew of "Birmingham" could hear hammering from inside the boat from attempted repairs, and so fired on her but missed. As the U-boat began to dive, she rammed her, cutting her in two. "U-15" went down with all hands, the first U-boat loss to an enemy warship. "Birmingham" also sank two German merchant ships that year and took part in the Battle of Heligoland on 28 August, and the Battle of Dogger Bank in January 1915.