In early 1918, it seemed to many that the British people and their allies were close to defeat. At home, the chief culprit was the German U-boat. Sailing almost unopposed from the North Sea ports of Zeebrugge and Ostend, the submarines were taking a heavy toll of allied shipping, and no one seemed to be doing anything about it. The job eventually went to Vice-Admiral Roger Keyes ("The Modern Nelson"), who had a long record of close action with enemies...