A particularly daring raid took place on the night of February 1, 1915, when a number of submarines tried to scuttle ships lying at Dover. The attack failed, but drew fire from the guns of the fort here.[1] [Footnote 1: See chapter on "Exploits of the Submarines."] On the 5th of February, 1915, the German Naval Staff announced that beginning February 18, 1915, the waters around Great Britain would be considered a "war zone." This was in retaliation for the blockade maintained against Germany by the British navy. The proclamation read as follows: "The waters round Great Britain and Ireland, including the whole of the English Channel, are herewith proclaimed a war region. "On and after February 18, 1915, every enemy merchant vessel found in this war region will be destroyed without its always being possible to warn the crew or passengers of the dangers threatening. "Neutral ships will also incur danger in the war region, where, in view of the misuse of the neutral flags ordered by the British Government and incidents inevitable in sea warfare, attacks intended for hostile ships may affect neutral ships also. "The sea passage to the north of the Shetland Islands and the eastern region of the North Sea in a zone of at least thirty miles along the Netherlands coast is not menaced by any danger. (Signed) Berlin, February 4, 1915, Chief of Naval Staff, VON POHL." [Illustration: The German Submarine War Zone.] The effect of this proclamation, which was in truth nothing more than official sanction for the work that the submarines had been doing for some weeks, and which they continued to do, was to bring Germany into diplomatic controversy with neutral countries, particularly the United States; such controversy is taken up in a different chapter of this history. In connection with the naval history of the Great War it suffices to say that such a proclamation constituted a precedent in naval history. The submarine had heretofore been an untried form of war craft. The rule had formerly been that a merchantman stopped by an enemy's warship was subject to search and seizure, and, if it offered no resistance, was taken to one of the enemy's ports as a prize. If it offered resistance it might be summarily sunk. But it was impossible for submarines to take ships into port on account of the patrols of allied warships; and the limited quarters of submarines made it impossible to take aboard them the crews of ships which they sank.