On 23–24 October, the High Seas Fleet undertook its last major offensive operation under the command of Admiral Pohl, though it ended without contact with British forces. Weakened by hepatic cancer and unable to carry out his duties, he was replaced by Vice Admiral Reinhard Scheer in January. Scheer proposed a more aggressive policy designed to force a confrontation with the British Grand Fleet; he received approval from the Kaiser in February. Scheer's first operation was a sweep into the North Sea on 5–7 March, followed by two more on 21–22 March and 25–26 March. During his next operation, "Oldenburg" supported a raid on the English coast on 24 April 1916 conducted by the German battlecruiser force. The battlecruisers left the Jade Estuary at 10:55 and the rest of the High Seas Fleet followed at 13:40. The battlecruiser "Seydlitz" struck a mine while en route to the target, and had to withdraw. The other battlecruisers bombarded the town of Lowestoft unopposed, but during the approach to Yarmouth, they encountered the British cruisers of the Harwich Force. A short gun duel ensued before the Harwich Force withdrew. Reports of British submarines in the area prompted the retreat of I Scouting Group. At this point, Scheer, who had been warned of the sortie of the Grand Fleet from its base in Scapa Flow, also withdrew to safer German waters.