British home army in the First World War bridge between Tilbury and Gravesend. There were fears that a German fleet protected by mines and submarines could land a 100,000-strong force before the British Grand Fleet could steam the south from its base at Scapa Flow. To counter this threat, the Admiralty redeployed pre-dreadnought battleships and submarines closer to vulnerable ports, expanded the coastwatch and increased patrolling of the North Sea. In October, Churchill responded to Kitchener's call for the Royal Navy to take more specific precautions against invasion by insisting that the role of the Grand Fleet was to eliminate an invader's covering fleet rather than defeat the
Baltic Sea British and French fleet attacked the Russian fortresses in the Baltic. They bombarded Sveaborg, which guards Helsinki; and Kronstadt, which guards Saint Petersburg; and they destroyed Bomarsund in the Åland Islands. After the unification of Germany in 1871, the whole southern coast became German. World War I was partly fought in the Baltic Sea. After 1920 Poland was connected to the Baltic Sea by the Polish Corridor and enlarged the port of Gdynia in rivalry with the port of the Free City of Danzig. During World War II, Germany reclaimed all of the southern and much of the eastern shore