German submarine blockade begins

On 18 February 1915 the two-week deadline set in the German declaration of 4 February expired. The waters around Great Britain and Ireland, including the English Channel, became a war zone in which German submarines were to sink enemy merchant ships without warning. In Britain and in Germany people spoke of the start of the submarine blockade of the British Isles.

The last days before the deadline

For two weeks there was a hectic exchange of notes. On 10 February the United States government warned Berlin that it would hold it strictly accountable for any attack on American ships and citizens, and at the same time protested in London against the use of the American flag by British ships. The German reply, signed by the Foreign Secretary, Gottlieb von Jagow, was dated 16 February. In it the Germans presented submarine warfare as defence against the British blockade, which was meant to starve the civilian population. They proposed talks on convoying American ships carrying no contraband and hinted that if Britain began to observe the Declaration of London and let food through to Germany, they might abandon submarine warfare.

The American warning made an impression in Berlin. According to some studies, in mid-February the Kaiser ordered U-boat commanders to spare ships under neutral flags. In practice, however, this rule did not fully protect them, because a submarine commander watching a ship through the periscope often could not be sure whom he was dealing with.

Preparations on both sides

The British expected the U-boats to strike above all at the troop transports crossing the English Channel to France. On 18 February the Admiralty ordered the daytime sailings of the mail steamers from Folkestone to Boulogne, Calais and Dieppe to be stopped. From then on they were to sail only at night. In the Strait of Dover drifters laid out newly introduced steel nets which were meant to detect submerged submarines. On 17 February a gale prevented them from putting to sea, but on the morning of 18 February some of them were back on station. In the afternoon something under water broke one of the nets and dragged it along for about five kilometres. Because of the dusk and the swell it could not be established whether it was a submarine.

The war zone paralysed some neutral shipping. In mid-February the Netherlands suspended the mail steamer sailings from Flushing to Folkestone and the lines linking Rotterdam with London and Le Havre. Other shipowners announced that their ships would sail as usual, but there were difficulties in insuring ships and cargoes, and seamen were reluctant to set out into the danger zone.

The first victims

During the night of 17/18 February a submarine torpedoed without warning, off the coast of Normandy near Dieppe, the French steamer Dinorah, chartered by the French Ministry of War. The ship did not sink and was towed into port. The next day the Norwegian tanker Belridge was torpedoed in the Strait of Dover, the first neutral ship hit in the new campaign.

On 20 February U-30 attacked in the Irish Sea, off the coast of Anglesey. It torpedoed without warning the British steamer Cambank, carrying a cargo of copper from Huelva in Spain to Liverpool. The ship sank within about 20 minutes, and four members of the crew were killed. The same day the Germans sank nearby the small British coaster Downshire, whose crew survived.

Neutral countries were threatened not only by submarines. On 19 February in the North Sea, near the German island of Borkum, the American steamer Evelyn, carrying cotton to Bremen, struck mines. One man was killed. Three days later, also in the North Sea, another American cotton ship, Carib, was sunk by a mine. Although both sank outside the war zone, their fate showed how dangerous shipping to Europe had become.

War on trade

The campaign was only getting under way. On 23 and 24 February U-8 sank five British ships in the English Channel near Beachy Head. The losses did not, however, threaten the supply of Britain, which had the largest merchant fleet in the world. The Germans could send only a few submarines into British waters at a time, and the great majority of ships still reached British ports safely.

The political consequences proved more important. Sinking ships without warning, and often with their people on board, caused outrage in neutral countries, especially in the United States. The first German campaign of submarine warfare was to last until the autumn of 1915 and lead to the most serious crisis in relations between Berlin and Washington since the beginning of the war.