Map of western Europe from the Mediterranean to the North sea, including France and Belgium, the Western Front.
Between Great Britain and continental Europe, the North Sea opens to the Atlantic Ocean to the north and through the English Channel to the south. Through the Skaggerak strait and Germany's Kaiser Wilhelm Canal it connects to the Baltic Sea.Germany's military ports on the Sea included Cuxhaven and the island of Helgoland.On maneuvers in the North Sea in July, 1914, after the assassination of the heir to the throne of Austria-Hungary, the Royal Navy stayed at sea.At the end of August 1914, the fleet attacked the German ships at Helgoland.The British seemingly had free range of the North Sea, and could wait for a German fleet to come from port to engage it. But on September 22, 1914, the German submarine U-9 sank three British battle ships in little more than one hour.Britain's home base of Scapa Flow had little protection from submarines. In November 1914, responding to a report of a periscope, the Fleet redeployed out of the North Sea. In its absence, German shelled the British coastal towns of Yarmouth (November 3, 1914), Whitby and Scarborough.On May 31, 1916, Britain and Germany fought the Battle of Jutland, the greatest naval encounter of the war.In August 18 and 19, 1916 , the German fleet again came out. The British raced to meet it, but ran into a submarine ambush. The British did not contest the German fleet in the southern North Sea after that.In 1915 Germany declared a and war zone around the British Isles. Germany's two campaigns of unrestricted submarine warfare were in part responses to Britain's blockade.
The North Sea is a sea.