Though there was only one major sea battle, and that was inconclusive, the war at sea was of critical importance in deciding the final outcome of the war. This is due to the blockades – one successful, one ultimately disastrous – that each side imposed on the other. It is this “battle of the blockades” that this short piece will focus on.
In the war at sea Britain held most of the advantages. It was strategically better placed as well as better equipped to enforce an effective blockade. It was an island, off the coast of mainland Europe whereas Germany only had a small coastline. Britain had also won the Naval Race, it had more ships, different types of ships and better ships. It also had the navies of France in the Mediterranean, Russia’s in the Baltic and the Black Sea, the Japanese in the Pacific, and then, when Italy joined the fray, their fleet in the Adriatic, and finally, America’s in the Atlantic. Besides, even if Germany’s warships had broken out and reached open sea, they didn’t have the fueling stations that Britain had with its world-wide empire. They would need to head for home ports to refuel and so repeatedly run the gauntlet.
At the outbreak of war, Britain moved immediately to not only blockade Germany, but to prevent the German navy from leaving its ports. The British laid mines outside of Germany’s ports and guarded the North Sea and English Channel, and made sure that both the North Sea and the English Channel were firmly under the control of the British Navy. Germany made its own moves, however, and on the second day of the war, mined waters outside of Britain’s three-mile limit, an act made illegal by the Second Hague disarmament conference of 1907.
This led Britain, on November 3rd, to declare the whole of the North Sea a ‘military area’. Britain could mine the approaches to the North Sea and use surface ships to patrol the unmined channels. Neutral ships would be obliged to stop in British ports where they would be searched for German supplies before being escorted through the mined waters to their port of destination. Though this might still annoy neutral powers, no ships needed to be sunk and no civilians killed. So, immediately there was a difference in the way Britain and Germany dealt with neutral shipping: no neutral ships needed to be sunk by British mines if they agreed to be escorted into British ports to be searched, whereas the whereabouts of German mines were unknown (many were ‘floating mines’, itself illegal) resulting in the loss of hundreds of neutral ships.
Ultimately, however, Germany had to blockade Britain from the Atlantic and could only access those waters, which were of course extensive, with submarines, the Unterseebooten or U-Boat, and submarines could only stop ships by sinking them, provoking widespread hostility from neutral powers, especially America. At the outset of war, Germany had less than 30 U-Boats but it built more than 300 and transferred crew from surface ships to submarines.
Germany’s U-Boat campaign was enough to genuinely threaten Britain with defeat. Britain, as a small island, relied totally on sea routes to adequately supply its military and its civilian population. The longer the war went on, the more critical supplies became. This was total war, and both sides were attempting to blockade the other.
In February, 1915 the Germans announced that they were to begin a submarine blockade of Britain and would sink any ships approaching Britain with military supplies or even food. They even placed reminders in New York newspapers, warning that travellers sailing in the war zone on ships to Great Britain or her allies did so at their own risk. One such notice could be found directly next to a British Cunard Line advertisement for Atlantic crossings on the Lusitania. And in May 1915, the Lusitania, a passenger liner, was sunk with the loss of 1,198 lives (including 139 Americans). It was carrying arms and but the sinking caused a tremendous outcry, nowhere more so than in America, and led to a promise from Germany that they would comply with the maritime law with respect to neutral merchant shipping. However, this weakened the effectiveness of the German blockade.
Pressure from the German navy, and from the army too, built on the Kaiserin 1916 to let loose the U-Boats again. But they had to be unrestricted, i.e. sinking any ship, even neutral ships, which were supplying the enemy. The failure to bleed the French to death at Verdun focused German minds. Stalemate on the Western Front would only continue and Germany could not win such a war, though could lose it.
The Kaiser presided over a meeting of the Crown Council on January 9th, 1917. The Chief of the Naval Staff, Admiral von Holtzendorf opened the discussion assuring the Kaiser that Britain would be made to sue for peace in six months, and when the Kaiser voiced his concern that America might be brought into the war if its ships were sunk, von Hotzendorf assured him that not one American would land in Europe. Hindenburg and Ludendorff added their weight to the debate. For Hindenburg it was a matter of starving Britain of military supplies. Bethmann-Hollweg was concerned not to provoke the Americans but his was a lone voice and the decision was made. Unrestricted submarine warfare would commence on February 1st.
It was calculated that 600,000 tons of shipping could be sunk each month (more than one-and-a-quarter million tons had been sunk in all of 1916). Consequently, on February 1st, 1917 ‘unrestricted submarine warfare’ was resumed. And it came close to success. Britain was vulnerable at sea. In April, 1917 almost 900,000 tons were sunk, in May almost the same. The predictions seemed to be right: Britain was in serious trouble and John Jellicoe, the First Sea Lord or Admiral of the Fleet, was in despair. He couldn’t see how Britain could continue in the face of such losses and he didn’t know what to do about it.
By the end of 1918 rationing was introduced in Britain.
On Lloyd George’s insistence (Jellicoe was actually against the idea), the British navy adopted a convoy system by which merchant shipping could be protected, the first of them sailed on May 10th. Losses remained high but never again reached those of April or May. By the end of the war more than 2,000 British naval and merchant ships had been sunk and more than 12,000 sailors and merchant seamen killed, but by early 1918 the British were building ships at a faster rate than they were losing them, and more than 200 U-Boats had been sunk with more than 5,000 lives lost. Still, the German U-Boat had come close to winning the war for Germany. Instead, it helped bring America into the war in April, 1917 (in October the previous year, President Wilson had declared neutrality to be a thing of the past. ‘The nature of modern war’, he said, ‘leaves no State untouched.’[1]) and with America’s entry into the war, American warships joined the blockade of Germany, for example undertaking convoy escort duties.
[1] Quoted in Martin Gilbert, World War One, p. 292