Unrestricted submarine warfare begins

On 1 February 1917 the announcement that Germany had made the day before came into force. In zones around Great Britain, France and Italy and in the eastern Mediterranean, submarines were from now on to sink without warning every ship they encountered, including those under a neutral flag. Admiral Henning von Holtzendorff promised that in this way he would force Britain to make peace within five months. The first weeks seemed to prove him right, although at first the most dangerous weapon turned out to be not the tonnage torpedoed as such, but fear.

The first days

According to the loss records, on 1 February alone German submarines sank nine vessels: the Spanish steamer Butron, the Dutch Gamma, two Norwegian ships, a French one, and British fishing boats. The following days brought ever longer lists. According to the British official history of the war at sea, in the first week of February 35 British and foreign ships went to the bottom in the English Channel and the Western Approaches to the British Isles. On 7 February the submarine U-85 torpedoed without warning the British passenger ship California about 38 miles from the Fastnet rock off the coast of Ireland. The steamer, armed with a single gun on the stern, sank in ten minutes, and more than 40 of her crew and passengers were killed, among them women and children.

Submarine commanders behaved in different ways. Some, like Kapitänleutnant Hans Rose of U-53, stopped ships with a warning shot, let the crews get into the boats and towed them towards land. Others torpedoed from concealment, especially armed ships, which could themselves sink a surfaced submarine. At the beginning of February a submarine fired on the boats carrying the crew of the British steamer Eavestone. The master and three seamen were killed, among them an American citizen.

Paralysis of neutral shipping

The Germans reckoned that at least two-fifths of neutral shipowners would stop sailing to England out of fear. Reality exceeded these expectations. British and French shipowners did not change their sailing schedules, but British, Allied and neutral ports filled with ships held back on their owners’ orders. Dutch sailings to Britain were suspended immediately after the German declaration was announced. In the United States the International Mercantile Marine company cancelled its sailings indefinitely, and Standard Oil recalled by radio the tankers heading for the zone. According to the British official history of seaborne trade, in the first nineteen days of February only five American freighters left America for the blockaded ports.

The British government was prepared for this. As early as 1 February it ordered all neutral ships in United Kingdom ports, about 600 vessels, to be held until their countries gave guarantees that they would not withdraw their fleets from trade with the Allies. The next day the few American, Spanish and South American ships were released, and ships sailing on behalf of the Allies were let go once their owners undertook not to take them to a neutral port. Dutch and Scandinavian ships, on the other hand, could return home only when another ship of the same flag arrived in a British port. This rule was called “ship for ship”. Even so, in February Swedish, Danish, Dutch and Spanish ships brought to British ports only a fraction of the previous year’s cargoes. In terms of the tonnage of ships entering, the shipping of the Scandinavian countries, the Netherlands and Spain fell from over 550,000 net tons in February 1916 to under 170,000. Only the Norwegians kept up more traffic. Neutral governments, from Scandinavia to South America, protested against a blockade that covered seas far from the enemy’s coasts and by its very nature could not be effective in the sense of the law of war. For the time being only the United States decided to break off relations with Germany.

The dispute over convoys

The Admiralty under John Jellicoe reinforced the base at Queenstown with four destroyers from the Grand Fleet and a flotilla of sloops. Above all it tried to route ships along patrolled coastal lanes, and on 19 February it decided to extend as far as the river Tyne the war channel laid out at the beginning of the war, along which ships sailed down the east coast of England from the Thames to the mouth of the Humber. The idea of sailing ships in convoys (PL) escorted by warships came up more and more often, because ships were losing a great deal of time waiting in port and making detours round dangerous waters. In February the Admiralty invited ten masters of merchant ships from the port of London to a meeting. Their opinion was discouraging: the best officers and seamen were already serving in the navy, the ships lacked proper signalling between the bridge and the engine room, and poorer coal made it impossible to keep a steady speed, so the masters could not guarantee to keep station. The Admiralty added that a convoy was a bigger target for a single submarine and, above all, that there were not enough destroyers and cruisers for escort.

On short routes escort was easier to organise. In February the coal trade to France, in which many unarmed neutral ships sailed, was brought into a system of so-called controlled sailings: every day groups of ships left four collecting ports in the south of England under the protection of warships. Losses in this trade proved so small that in the spring there were demands for convoys on the ocean as well.

February ended with a heavy balance for the Allies. According to the British official history, ships with a total tonnage of about 540,000 tons were sunk that month as a result of enemy action, of which more than 310,000 were British. In April losses reached 880,000 tons, the highest of the whole war. Only the introduction of ocean convoys from May 1917 began to turn the situation round.