Other incidents of naval warfare than the German submarine campaign added to the public discomposure. On 17 October two German cruisers sank two British destroyers and nine convoyed Norwegian merchant ships between the Shetlands and the Norwegian coast; on 12 December somewhere in the North Sea four German destroyers sank five neutral vessels, four British armed trawlers, and also one of the two British destroyers accompanying them, the other being disabled, while two British trawlers and two neutral vessels were also sunk off the Tyne; and on the 23rd, three British destroyers were mined or torpedoed off the Dutch coast. On the 26th it was announced that Sir Rosslyn Wemyss had succeeded Jellicoe as First Sea Lord, and other changes were made at the Admiralty. But the unpleasant incidents continued. On 14 January 1918 Yarmouth was, after a long immunity from such attacks, once more bombarded by enemy destroyers; on 15 February a British trawler and seven drifters were sunk by similar means in the Straits of Dover; and on the 24th the safe return was announced of the German raider Wolf after a cruise in which she had sunk eleven vessels in the Indian and Pacific Oceans. The extension of submarine warfare to the sinking of hospital ships was more shocking as an exhibition of barbarity than alarming as a proof of naval efficiency, and may even have been designed as a desperate measure to commit Germany beyond recall to the alternative of victory or irredeemable ruin. As an outrage against international morality it was only exceeded by the torpedoing on 6 June of a Dutch vessel on which British delegates were to have gone to The Hague to discuss with Germans the mutual amelioration of the lot of prisoners of war.