When war came these calculations were falsified. The German High Seas Fleet found itself unable to stand up to ours, and German war policy was forced to take a different direction. The U-boats’ first allotted task was the legitimate one of reducing our margin of superiority in battle-ships and cruisers. While our Fleet was certain to keep the sea, and protect our long coast-line and huge merchant tonnage, the German High Seas Fleet must lie in the Kiel Canal, risking only furtive and futile rushes into the open. But if the U-boats could hit a sufficient number of our more active war-ships, they might bring the forces nearer to an equality, and perhaps establish a prestige for their own Service. How they failed in this attempt we shall see presently. When their failure in the game of attrition became evident, the U-boats were utilised in a different way. A submarine blockade of the British Isles was plainly threatened by Admiral von Tirpitz towards the end of 1914; and the official announcement of it was made on February 4, 1915. By this document it was declared that on and after February 18, every British or French merchant vessel found in the waters of the ‘war region’ round these islands ‘will be destroyed, without its always being possible to warn the crews or passengers of the dangers threatening.’ Neutral ships, it was added, would not be attacked unless by mistake; but they are warned not to take the risk. Those who know even a little of the history of our old wars will see at a glance that this is a new move in naval war policy, and one made by the Germans to get over certain difficulties which arise from the very nature of submarine boats, and which are especially embarrassing when the submarines belong to a navy decidedly inferior to its enemies at sea. The old and well-established rules of naval war laid down that you could only interfere with merchant shipping if it were engaged in carrying contraband of war. To ascertain whether the ship you had sighted was carrying contraband or not, you had to board and search her. If innocent, you must let her proceed on her voyage. If apparently guilty, you took over her men or otherwise placed them in safety, put a prize crew on board and sent her home to a port of your own, to be tried legally by a properly constituted tribunal called a Prize Court. If this Court decided that she was, in fact, carrying contraband, she was your prize. If you were forced by stress of circumstances to destroy the prize, instead of sending her into port, you took every care to remove everyone on board before doing so; and when you had not room for so many people, you released the prize rather than endanger or sacrifice the lives of non-combatants.