Iron Duke collided with the tanker on 12 January 1916 while in Scapa Flow, and the latter sank. The tanker had come loose during a severe gale, which had winds of up to . Iron Duke was undamaged in the accident. The typical routine of gunnery drills and squadron exercises occurred in January.Jellicoe, pp. 267–269 The fleet departed for a cruise in the North Sea on 26 February; Jellicoe had intended to use the Harwich Force to sweep the Heligoland Bight, but bad weather prevented operations in the southern North Sea. As a result, the operation was confined to the northern end of the sea.Jellicoe, p. 271 On the night of 25 March, Iron Duke and the rest of the fleet sailed from Scapa Flow to support the Battlecruiser Fleet and other light forces that raided the German zeppelin base at Tondern. By the time the Grand Fleet approached the area on 26 March, the British and German forces had already disengaged and a severe gale threatened the light craft. Iron Duke guided the destroyers back to Scapa while the rest of the fleet retired independently.Jellicoe, pp. 279–280
