About a week after the Hartlepools raid, von Tirpitz, who was then at the head of the German Admiralty, told the Americans that they had stopped their trade with Germany because Great Britain had ordered them to do so, and he asked them how they would like to see all trade with Britain stopped by German submarines. Then came the Battle of the Dogger Bank, in which the German vessels scuttled for home as soon as they sighted the British fleet, but in the course of their flight lost the _Bluecher_. It was after this discreditable affair that von Tirpitz decided to carry out his threat. He gave notice to the President of the United States that on and after 18th February the waters surrounding the British Isles would be considered to be within the seat of war, and that all enemy merchant ships found in these waters would be sunk by German submarines. He also said that it might not always be possible to save the crews and the passengers of these ships, and that neutral vessels within this zone of war would be exposed to danger, and might even be sunk. To this the President replied, begging Germany to consider carefully before taking any such action, and warning her that the destruction of a United States ship or the death of American citizens would be considered an unfriendly act which might lead to war. The President then went on to point out that, until a blockade--that is, a complete stoppage of sea trade--could be carried into effect, the sole right which fighting nations possessed with regard to neutrals was to visit and search their ships in order to discover whether or not they were carrying contraband, and, if so, to bring them into port, where a court would adjudge them guilty or not guilty. [Illustration: A German Submarine awash. _Photo, Central News._]