Great Britain declared the entire North Sea a military zone as of November 5, 1914, imposing a blockade of Germany with nets, mines, and ships from Scotland across the northern end of the North Sea, and at the mouth of the English Channel. Germany's response depended on its submarine fleet.

Die Blockade Englands

Unsere Unterseeboote bei der Arbeit



The Blockade of England

Our submarines at work



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On maneuvers in the North Sea when the Archduke was assassinated, the British fleet remained. Much of the fleet was in Portsmouth on Britain's south coast, but transferred through the Straits of Dover to Scapa Flow on the Scottish North Sea coast the night of July 29. The movement put the Fleet on the high seas, less subject to German submarines and mines, and in a position to control the North Sea.

On August 1, after receiving word that Germany had declared war on Russia, English Foreign Secretary Sir Edward Grey told the French Ambassador that Britain would not allow the German fleet into the English Channel. Grey reported to Parliament that the Germans, who had already invaded Luxemburg and delivered their ultimatum to Belgium, were willing to comply with Britain's demand.

Great Britain declared the entire North Sea a military zone as of November 5, 1914. It was well-positioned to impose a blockade of Germany with nets, mines, and ships from Scotland across the northern end of the North Sea, and at the mouth of the English Channel. Other Allied points of control included Gibraltar, Suez, and locations off Barcelona, Spain and Genoa, Italy.

By international law, ships intercepted under the blockade were to be inspected on the high seas. The Allies argued this put them at risk from submarines and instead diverted them to port, contrary to law. When some neutral ships were sunk by German mines, Britain deployed mines, then argued diversions would allow it to provide safe passage to ships along the coast of Britain.

Britain's blockade became increasingly restrictive as neutral ships were stopped and boarded, originally for military supplies, but increasingly for anything that could have a military use.

The blockade put the Allies at odds with neutral nations including the United States. Netherlands, Denmark, and Sweden could trade directly or across the Baltic, and were also transit points for other nations.