slipping into the Atlantic. Major battles included those at Heligoland Bight (in 1914 and again in 1917), Dogger Bank (in 1915), and Jutland (1916). Though British tactical success remains a subject of historical debate, Britain accomplished its strategic objective of maintaining the blockade and keeping the main body of the High Seas Fleet in port for the vast majority of the war. The High Seas Fleet remained a threat as a fleet in being that forced Britain to retain a majority of its capital ships in the North Sea. The set-piece battles and maneuvering have drawn historians' attention; however, it was the naval blockade of food and raw material imports into Germany which ultimately starved the German people and industries and contributed to Germany seeking the Armistice of 1918. English Channel Although the English Channel was of vital importance to the British Expeditionary Force (BEF) fighting in France, there were no big warships of the British Royal Navy in the channel. The primary threat to the British forces in the channel was the German High Seas Fleet based near Heligoland; the German fleet, if let out into the North Sea, could have destroyed any ship in the channel. The German High Seas Fleet could muster at least 13 dreadnoughts and many armored cruisers along with dozens of destroyers to attack the channel. The High Seas Fleet would be fighting against only six armored cruisers that were laid down in 1898–1899, far too old to accompany the big, fast dreadnoughts of the Grand Fleet based in Scapa Flow. The U-boat threat in the channel, although real, was not a significant worry to the Admiralty because they regarded submarines as useless. Even the German high command regarded the U-boats as "experimental vessels". Although the channel was a major artery of the BEF, it was never attacked directly by the High Seas Fleet. Atlantic While Germany was strangled by Britain's blockade, Britain, as an island nation, was heavily dependent on resources imported by sea. German submarines (U-boats) were of limited effectiveness against surface warships on their guard, but were greatly effective against merchant ships. In 1915, Germany declared a naval blockade of Britain, to be enforced by its U-boats. The U-boats sank hundreds of Allied merchant ships. However, submarines normally attack by stealth. This made it difficult to give warning before attacking a merchant ship or to rescue survivors. This resulted in many