The blockade of Germany was part of the First Battle of the Atlantic between the United Kingdom and Germany during World War I.
The British established a naval blockade of Germany early in the war. As was shown later in the Battle of Jutland, the German fleet could not defeat the British fleet to break the blockade. The blockade was unusually restrictive in that even food was stopped, as it was said to help the war. The Germans regarded that as an attempt to starve the German people into submission. They wanted to fight back and so blockaded Britain and France.
As Germany could not fight with the huge British Royal Navy on an even basis, the only possible way for Germany to impose a blockade on Britain was through the submarines. The Chancellor of Germany was against that sort of blockade because it meant attacking neutral ships, such as those of the United States, as well. However, the military pushed unlimited submarine warfare forward.
On 4 February 1915, Kaiser Wilhelm II of Germany declared the seas around the British Isles a war zone. Effective 18 February, Allied ships in the area would be sunk without warning. British ships hiding behind neutral flags would not be spared, but some effort would be made to avoid sinking clearly-neutral vessels.
Up to 750,000[1][2] civilians may have died because of starvation caused by the blockade during the war. Many more would die from starvation after the armistice in November 1918, as the blockade was continued into 1919 to force Germany to sign the Treaty of Versailles in June 1919.