The Last Raider — Douglas Reeman

December 1917: Germany opens the final, bitter round of the war with a new and deadly weapon in the struggle for the seas. When the Vulkan sails from Kiel Harbour, to all appearances she is a harmless merchant vessel. But her peaceful lines conceal a merciless firepower of guns, mines, and torpedoes that can be brought into play instantly. For the Vulkan is the last of the German commerce raiders, tasked with breaking through the British blockade and then heading west and south to the open seas. And under crack commander Felix von Steiger, her mission is to bring chaos to the Allied seaways.