Where was the British blockade located

The British Blockade of Germany, or the Blockade of Europe, occurred from 1914 to 1919. It led to Germany declaring waters surrounding Britain to be a war zone, which led to the sinking of a US vessel and the entrance of the United States into the War. British Blockade of Germany

Explanation: i have no explanation what so ever :P

united states reinforcements contributed greatly to three allied victories in france at: cantigny (first major american battle), argonne (the largest in the united states military history, involving 1.2 million american soldiers), and château-thierry (one of the first actions under general pershing).