In 1914, Great Britain established a naval blockade to prevent all overseas importations to Germany, therefore, Germany's economy can't sustain without any goods, or ammunitions and weapon aids. What led Great Britain to imposing the naval blockade on Germany is because the German naval command started to enforce their "Unrestricted Submarine Warfare" policy in which they would attack any country's ships around the British Isles. Disregarding the countries the status of association to World War I, any ships and merchants near this zone would be attacked by the German Navy. This angered Great Britain, and that's why they placed a naval blockade to Germany in 1914.