One of the most well-known instruments of German warfare are the U-Boats, submarines which gained fame during the First and Second World Wars through their attempts to cut Great Britain off from world trade by sinking merchant shipping. On August 6th, 1914, two days after Britain declared war on Germany in WWI, ten U-Boats left their bases on the island of Heligoland to attack British shipping for the first time.
Initial U-Boat actions met with little success. Beset with engine failure, one submarine had to turn back, and another, U-15, was sunk after she failed to torpedo an enemy vessel and was instead rammed by a cruiser. However, the destruction of U-15 gave the British the impression that submarines were little threat to surface warships, which forced the Germans to further develop their doctrine. On September 5th, the threat of submarines was made known when U-21 sank the HMS Pathfinder, the first victory of a modern submarine over a warship. Later that month, U-9 sank three British cruisers and in October she would sink another. Each member of the crew, except the captain, was awarded the Iron Cross; Captain Weddigen was awarded the Iron Cross First Class. Also in October, the first attacks on shipping took place. The British Navy was numerically superior to the German one, and so was able to maintain a blockade. The Germans looked to their submarines to sink ships carrying food for Britain in order to visit upon the British population the same hunger that the German people were experiencing. The U-Boats would continue their attacks against British shipping and military vessels, but the British introduction of the convoy system and arming of merchant ships would lead to a decrease in submarine effectiveness and an increase in their losses. Although the total value of ships sunk far exceeded the value of U-Boats lost, there were simply too few U-Boats and too many escorts, and thus Germany was unable to adequately disrupt British trade.
The U-Boats were an attempt to remove the advantages afforded Britain by its status as an island nation. Germany, situated as it is in the middle of Europe between often hostile nations, is inherently less connected to the maritime world. As an island nation, Britain has long had an intense focus on its navy, and for centuries it was the premier ocean-going power. Both Britain and Germany were dependent on food imports, but Britain’s navy ensured that her imports could be protected while Germany, focused on its large land army, was always at risk of losing food aid to enemy blockade. Thus, Germany built submarines to subvert British naval supremacy. In both world wars, however, German submarines have proven insufficient to overcome the Royal Navy. Until land powers can find a way to cheaply undo the advantages of an expensive navy, it seems that they will largely be at the mercy of naval powers in a long and drawn-out war.