In retaliation for having her flag swept from the seas, Germany's submarines, during the second six months of the war, had sunk a total of 153 merchant ships, including those belonging to neutral countries as well as to her enemies. The total tonnage of these was about 500,000 tons; 1,643 persons died in going down with these ships.
Not of the least importance were the precedents that were established, or attempted to be established, by Germany in conducting naval warfare with her submarine craft. In a note delivered to the United States Government, the German Government declared that British merchant vessels were not only armed and instructed to resist or even attack submarines, but often disguised as to nationality. Under such circumstances it was assumed to be impossible for a submarine commander to conform to the established custom of visit and search. Accordingly, vessels of neutral nations were urgently warned not to enter the submarine war zone. The war zone which she proclaimed about Great Britain had no precedent in history, and it immediately brought to her door a number of controversies with neutrals, particularly the United States. The sinking of liners carrying passengers claiming citizenship in neutral countries was another precedent, which had the same effect with regard to diplomatic exchanges.
Predictions that had been made long before the war came were found to be worthless; there were those who had predicted that Germany in the event of war with England would give immediate battle with her largest ships; but twelve months went by without an actual battle between superdreadnoughts. "Der Tag" had not come. There were those who had predicted that the British navy would force the German ships out of their protected harbors. "We shall dig the rats out of their holes," said Mr. Winston Churchill, British Secretary of State for the Navy in the early months of the war. Mr. Churchill was removed from his position, and twelve months passed by with the German ships still in their "holes."
Certain lessons had been taught naval authorities of all nations through the actual use of the modern battleship in war. The first year showed that the largest ships must have very high speed and long gun range. To some extent the fact that the fighting ships of nearly all of the belligerent countries were thus equipped changed battle tactics.