The Germans ran the U-Boat campaign throughout World War I, and used the submarines to attack the Allies’ trade routes.
They mostly attacked around Britain and the Mediterranean, and destroyed almost 5,000 ships in total.
The campaign started in the North Sea, when 10 submarines were sent from Heligoland to attack Royal Navy ships. However, it was unsuccessful – only one torpedo was fired and it missed its intended target – HMS Monarch. Meanwhile, two of the U-Boats were lost.
The U-Boats had much more success when their attentions were turned to the war on commerce. Britain had already managed to block off Germany with its Navy, not even allowing food to enter the country, and since the Germans’ main navy was much weaker than the British, they fought back using U-Boats.
German U-boat submarines saw extensive action in both the First and Second World War (pictured: A U-boat surrenders in waters near Londonderry in 1945)
Admiral Hugo Von Pohl, commander of the German High Seas Fleet, declared the British and Irish seas a war zone, and the Germans send out 20 boats to form a naval blockade. They sunk a huge amount of trade boats heading into Britain.
In 1917, the Germans came up with the tactic of trying to 600,000 tons of shipping heading into Britain each month – they believed this would force their enemies to try for peace within six months. This was a huge success – 860,000 tons were sunk in April of that year alone, the British were left with just six weeks-worth of wheat, and the Americans were forced to declare war.
Towards the end of the war, the Allies had become far better at countering the threat of U-Boats. They used planes to patrol the seas – forcing them to go below the surface, where they were blind. The North Sea Mine Barrage then followed – when 70,000 mines were lain and destroyed six U-Boats between September and November 1918.
Upon the German surrender, the Allies insisted all U-Boats were also surrendered to them. Their last act was to suppress the German naval mutiny in October 1918 – revolt by sailors of the German High Seas Fleet.
In total, U-Boats sunk almost 13 million gross tons of Allies’ shipping. Of the 351 boats, 178 were lost in combat, with 5,000 people killed on board them.