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Chart: The North Sea
1915
From 1914 until Germany signed the Treaty of Versailles in June 1919, a dozen armed British merchant cruisers enforced a distant blockade of the German coast in the North Sea. By the time the blockade ended, they had boarded nearly 13,000 merchant ships, seizing all contraband, including foodstuffs, bound for Germany. The red squares overlaid on this chart were used by patrolling ships to indicate their position without revealing their latitude and longitude. |