page_title: History of the North Sea
section_title: The First World War
hierarchical_section_title: History of the North Sea / 20th century / The First World War
caption_attribution_description: English: The German battlecruiser SMS Seydlitz at Wilhelmshaven, Germany, after the Battle of Jutland, 31 May–1 June 1916.
context_page_description: The North Sea, though often an area of conflict, has an extensive history of maritime commerce and trade routes between its coastal nations whose economies and industries were also able to exploit its resources. The earliest records of Roman explorations of the sea begin in 12 BC. Southern Britain was formally invaded in 43 AD and gradually assimilated into the Roman Empire, beginning sustained trade across the North Sea and the English Channel. The Germanic Angles, Saxons, and Jutes began the next great migration across the North Sea during the Migration Period, conquering, displacing, and mixing with the native Celtic populations. The Viking Age began in 793 and for the next two centuries the Vikings ruled the North Sea.
  From the Middle Ages until the end of the 15th century, before the development of good roads, maritime trade on the North Sea connected the economies of northern Europe, Britain, and Scandinavia with each other as well as with the Baltic and the Mediterranean.
context_section_description: During the First World War, Great Britain's Grand Fleet based at Scapa Flow and Germany's Kaiserliche Marine faced each other across the North Sea.
  
  Due to its numerical advantage in dreadnoughts, the Grand Fleet obtained Naval superiority and was able to establish a sea blockade of Germany's coast.  The goal of the blockade was to deny Germany access to maritime trade including war materials and to guarantee the undisturbed ferrying of British troops.  Because of the strong defensive fortress of Heligoland, the Germans controlled the German Bight, while the rest of the North Sea and the English Channel were controlled by the Royal Navy for the duration of the war. 
  6 August 1914 saw the start of the German U-boat Campaign – two days after the United Kingdom declared war on Germany over the German invasion of Belgium, ten German U-boats left their base in Heligoland to attack Royal Navy warships in the North Sea.
  The first sea battle, the Battle of Heligoland Bight took place on 28 August 1914 and ended in a clear British victory.  Because of British surface naval superiority, the Germans initiated submarine warfare.  After several failures, the German submarine SM U-9 succeeded in sinking three British armored cruisers about 50 kilometres (27 nmi) north of Hoek van Holland, near the North Sea entrance to the English Channel.
  This ended British complacency about submarines.
  
  In November 1914, the British declared the entire North Sea a war zone and from there on out it was mined. Ships that sailed the North Sea under the flags of neutral countries without giving the British prior warning could be the target of British attack. 
  In the Battle of Dogger Bank (1915), the Germans suffered another defeat on the 24 January 1915 and in the aftermath, all attempts to break the allied blockade failed.  Due to these failures, on 4 February 1915, the Germans initiated unrestricted submarine warfare, in which, in addition to enemy ships, all neutral ships could be attacked.
  On 31 May and 1 June 1916, the Battle of Jutland, if measured by the number of participating ships (238), the largest naval battle in world history took place.  The German goal of significantly weakening the British Navy by sinking a large part of it and ending the blockade was not achieved.  Although the Germans won a tactical victory, their main fleet narrowly escaped destruction and they once again laid their hopes on the unrestricted submarine warfare.
  As the war was ending and contrary to the wishes of the new German regime, a final attack on the British Navy on 28 October 1918 was ordered. However, the outbreak of the Wilhelmshaven mutiny  in Kiel ended the naval war.  The mutiny was also a crucial step in the initiation of the November Revolution.
caption: The German battlecruiser SMS Seydlitz, took part in the battles of Dogger Bank and Jutland of World War I, scuttled at Scapa Flow, 1919
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