By Andrew Gordon
When the Earl of St Vincent was told of the ‘submarine’ invention of Robert Fulton, in 1804, he allegedly said: ‘Don’t look at it, and don’t touch it. If we take it up other nations will; and it will be the greatest blow at our supremacy on the sea that can be imagined.’ He was, in truth, being a little alarmist. A hundred years later not much progress had been made in the submarine’s threat to naval supremacy. But it was seen mainly as a defensive, almost immobile weapon, and Fisher envisaged it picketing Britain’s coastline and lying in wait for attacking or invading enemies. The Germans had built their first submarines, U-1 and U-2, contemporaneously with Dreadnought, and for several years they (at best) kept station, rather than blazed trail, in submarine experiment; and even 1914 saw the U-boat in an unadventurous light.
The very first ‘war cruise’ of the U-boats, on 2 August 1914 was a defensive positioning of submarines on sentry duty to seawards of Heligoland, but in the ensuing weeks and months the range and reliability of the boats were explored and established. The torpedoing of armoured cruisers Hogue, Aboukir and Cressy on 22 September by Otto Weddigen in U-9 turned preconceptions upside down. And as the ‘envelopes’ of endurance and operational capability (and sometimes ethical behaviour) were being tested to the limits into 1915, the Germans realised that they possessed a weapon with the range and endurance both to harry the Grand Fleet outside its bases, and to interdict Britain’s transatlantic trade.
The French had redoubled their frigate guerre de course efforts after Trafalgar, having nowhere else to go, and after Jutland the German naval high command similarly turned to the U-boats. Even as Scheer was being acclaimed as the victor of ‘Der Skagerrakschlacht’, he was arguing his way out of renewing the battle: ‘even the most successful outcome of a fleet action will not force England to make peace’ he told the Kaiser, with opaque reasoning which had not seized him before the Jutland experience, ‘a victorious end of the war within a reasonable time can only be achieved through the defeat of British economic life – that is, by using the U-boats against British trade’. This despairing, evasive document would have shocked the German public. It was a tacit admission that the British Grand Fleet was undefeatable, and that the High Seas Fleet was actually incapable of furthering Germany’s war aims. A useless waste of money, in other words – after just one shadowy, twilight, half-cocked brush with Jellicoe. The U-boat would have to be the saving of the German Navy and, perhaps, the war.
The U-boat arm had had a year’s grace to develop and define their own operational potential after the curtailing of the first ‘1915’ bout of unrestricted war against trade; and now, in the autumn and winter after Jutland and the High Seas Fleet’s near-escape from the Grand Fleet in August, they were properly let off the leash in defiance of international protest. The consequences were devastating. By the time Beatty succeeded Jellicoe in high command, merchant-ship sinkings were three times higher than at the time of Jutland, and the strategic focus of the naval war had shifted from the North Sea to the ‘Western Approaches’ of the Atlantic (the focal areas of shipping lanes north and south of Ireland). By April 1917 a dozen ships, Allied and neutral, were being sunk every day. At this rate the war would soon be lost.
Jellicoe had gone to the Admiralty partly to bring a blast of salt air to its musty corridors, and to grapple with the burgeoning U-boat problem. He failed. His administration set its face against the old answer to guerre de course, convoying, partly through doubts that merchant ships (to whom sailing in close company was anathema) could keep station, with their limited means of fine-tuning speed, but partly because of an obdurate quest for a technological rather than an organisational solution. After all, the armoured cruiser guerre de course threat had been kicked into touch by radical new technology, so why not the U-boats?
In fact, in the end, the new threat proved highly susceptible to the old solution, once the logistical and prejudicial obstacles to convoying had been surmounted. Convoying subjected the terminal ports to famine and glut cycles which degraded the operational efficiency of a merchant fleet by, say, 25–30 per cent (depending on the size of the convoys), but if that burden were accepted as the lesser of two evils, it was strikingly effective in tactical terms. For a start, an escorted convoy made it necessary for the U-boat to risk the proximity of one or more warships, if it was to press home an attack. That compelled the U-boat to attack submerged, depriving it of the use of its gun – by far the cheapest method of sinking a tramp steamer – and forcing it to expend one or more of its small outfit of torpedoes. The best attacking positions were as well known to the escorts as they were to the U-boat, and the need to remain submerged (and on waning battery power) meant that if the first salvo missed, there would probably be no second chance. Meanwhile the development of towed explosive sweeps, depth charges, hydrophones and destroyer tactics placed U-boats in ever greater danger. Almost 180 were sunk and, at the war’s end, a similar number meekly surrendered to the Allies. No wonder that, in the subsequent ‘interwar’ years, the U-boat was assumed to be a discredited weapon of the past – more especially in the light of the invention of Asdic.
By the end of the war some 12 million tons of shipping had been sunk by U-boats, some 7 million of it British (ten times more than by mine, the next most frequent cause of loss). But the curve of sinkings had taken a decisive downturn with the belated introduction of convoying and other countermeasures, and in 1918 the rate of losses fell by 71 per cent from its peak in the terrible spring of the year before, as successes came harder to U-boats, and the aces were progressively eliminated.
