The safety of Britain in particular lay on its ability to control the seas, and the German U-boat campaigns against imports from the USA and elsewhere brought Britain to the brink of running out of supplies.
Rationing was introduced as a direct result of the disruption and the Defence of the Realm Act (DORA) was subsequently introduced to prevent any future food crisis.
It also contributed heavily to the USA’s decision to intervene in the war. The sinking of US ships, together with the Zimmerman telegram (by which Germany conspired with Mexico to carve up a conquered USA) were threats the USA could not ignore.
1. The Battle of Heligoland Bight (August 1914) was the first naval battle of World War One
The British fleet ambushed and sunk three German light cruisers and one destroyer.
2. In 1914 SM U-9 (a German U-boat) sank 3 British armed cruisers in under an hour
3. On 7 May 1915 the cruise ship Lusitania was torpedoed by a German U-boat
1,198 people were killed, including 128 Americans. The wrecklessness of German submarine warfare was an influence on the United States decision to join the Allies in 1917.
4. Between October 1916 and January 1917 1,400,000 tons of Allied shipping was lost to German U-boats
5. Germany built 360 U-boats, 176 of which were lost
6. German unrestricted submarine warfare resulted in merchant ships being sunk without warning
Germany implemented the policy twice during the war, first in 1915 and later in 1917. Unrestricted submarine warfare rendered all vessels in waters around the UK a target, and U-boats could attack without warning, against traditional ‘prize rules’.
7. The Battle of Jutland (31 May – 1 June 1916) was the largest sea battle of the war
In the largest naval battle of the war, 14 British ships were lost to Germany’s 11. Britain also lost more than twice as many sailors than Germany. However, it was not the knock-out blow that the Germans required and the Royal Navy remained dominant in the North Sea.
8. The North Sea was heavily mined by both sides
Under a 1907 treaty opponents could only mine 3 miles off an enemy’s coastline but both sides ignored this rule.
9. The success of German U-boat attacks caused the disastrous Passchendaele offensive
A main reason why the Passchendale campaign was launched was to capture the German U-boats based at Flanders. The attack failed however, with Britain suffering massive casualties.
10. The Allied naval blockade of Germany (August 1914 – January 1919) was devastatingly effective
Germany was heavily reliant on imports. An academic study in 1928 put the death toll caused by the blockade at 424,000 lives.