The War at Sea in 1917
The U-boat war escalates. The US enters the war
author Paul Boșcu, August 2018
During 1917 Germany resumed unrestricted submarine warfare in an effort to stop the flow of supplies towards Britain. The attempt backfired when US President Woodrow Wilson declared war against Germany. The US fleet made an immediate impact, bolstering the already large numbers of the Grand Fleet. In an attempt to counter the German U-Boat campaign the Entente adopted a convoy system to escort merchant ships across the worlds seas.

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Having failed in 1916 to drive France from the war at the Battle of Verdun (on land), and the British at Jutland, and having, in turn, experienced the lengthy and damaging British attack in the Somme offensive (on land), in 1917 the Germans sought to force Britain from the war by resuming attempts to destroy its supply system. Unrestricted submarine warfare was resumed with one major consequence: the United States declared war against Germany. By the end of the year, the British managed to contain the German submarine threat by implementing a convoy system.

The seeds were set for unrestricted submarine warfare; yet this would be a gamble based on the lack of a realistic alternative rather than the inherent merits of the policy. German naval experts believed that they could knock Britain out of the war if they managed to sink some 600,000 tons of shipping a month for just five months. The British would simply run out of shipping while neutral shipping would either be frightened away or be sunk itself.

Ironically, America’s entry into the war increased the importance of submarines to German capability, since it increased the number of surface warships pitted against Germany. This prefigured the situation in 1941, when the United States entered the Second World War against Germany, although then the German surface fleet was relatively weaker.

The initial rate of Entente shipping losses was sufficiently high to threaten defeat. Serious losses were inflicted, especially on British commerce, in large part due to British inexperience in confronting submarine attacks. The limited effectiveness of anti-submarine weaponry was also an issue, as depth charges, another new technology, were effective only if they exploded close to the hull of the submarine. This was also a period when effective artillery techniques on land were still being worked out. It took time to establish and disseminate such techniques.

In the event, as later in the Second World War, Britain survived the onslaught, by fighting and defeating the submarines and also due to success on the home front. The introduction in May of a system of escorted convoys cut shipping losses dramatically and helped lead to an increase in the sinking of submarines.

Convoys were also resisted by certain naval circles as not being sufficiently in line with the bold ‘Nelson touch’, which they believed necessary and appropriate. To look after convoys was not the role of warriors. Nineteenth-century Royal Navy culture had blurred the success of convoys in the French Revolutionary and Napoleonic Wars from 1793 to 1815. However, against a background of resource superiority and a degree of naval control that enabled them to choose from different options, the Admiralty eventually took the necessary steps.

After the first fleet action in the dreadnought age, it is not surprising that there were a great number of technical and material considerations for the British to digest. One thing was evident: something had gone wrong with the battlecruisers, and a full investigation into their explosive demise was begun, resulting in strict anti-flash precautions being implemented, plus additional armor protection for all those ships still under construction. But urgent improvements were also required in the design of British shells, which had shown a distinct tendency to break up on impact, thus not causing the anticipated damage.

Night fighting may still have been abhorred, but Jutland forced a belated recognition of the necessity for proper training and preparations. There was a general tightening of ship-to-ship identification procedures, searchlights with removable covers were fitted, and night exercises were begun in earnest.

The method of handling and disseminating naval intelligence was also improved to avoid the kind of errors which had dogged Jellicoe at Jutland. The British had certainly learned some valuable lessons from their bitter disappointment.

Despite their protestations of victory, the Germans were deeply chastened by some aspects of their Jutland experience. They knew they had done well, but they also knew how close they had come to annihilation. Whatever they would do next, it would not involve another fully fledged fleet confrontation. With successful fleet action ruled out, there seemed to be only one option left that promised any concrete results against their implacable enemy: submarine warfare. In October 1916 the Germans took their first cautious steps when they announced a return to restricted submarine warfare.

‘In view of England’s plan of campaign, there was no alternative but to inflict direct injury upon English commerce. We could not build a sufficiently great number of additional large ships to compensate for the inevitable losses which we were bound to suffer in the long run in a conflict with the numerically superior English fleet. We ought to have tried earlier what the result of a victory by our fleet would be. It was a mistake on the part of the naval leaders not to do so.’ (Admiral Reinhard Scheer, SMS Friedrich der Grosse, Third Battle Squadron)

The U-boats took a rising toll on British shipping, but they were still hamstrung by international conventions, and Admiral Reinhard Scheer wanted a far more robust approach: ‘A victorious end to the war at not too distant a date can only be looked for by the crushing of English economic life through U-Boat action against English commerce. Prompted by the convictions of duty, I earnestly advise Your Majesty to abstain from deciding on too lenient a form of procedure on the ground that it is opposed to military views, and that the risk of the boats would be out of all proportion to the expected gain, for, in spite of the greatest conscientiousness on the part of the Chiefs, it would not be possible in English waters, where American interests are so prevalent, to avoid occurrences which might force us to make humiliating concessions if we do not act with the greatest severity.’ (Admiral Reinhard Scheer, SMS Friedrich der Grosse, Third Battle Squadron)

Germany announced a full resumption of unrestricted submarine warfare, not only in the war zone around the British Isles but also across the Mediterranean and shortly afterwards – most controversially – off the eastern coast of the United States. By this time the German U-boat fleet had swollen to over 150 modern submarines with ocean-going capability, although only around a third could be maintained out on patrol at the same time. But this proved enough to cause chaos to the essential sea lanes that fed and supplied Britain.

As to the likely bellicose American reaction, the German High Command believed that US goods and services were effectively already at Britain’s beck and call: all that was missing was her armed forces. As the US Army was inconsequentially small, it would be more than a year before a mass army could be mobilized, by which time it would be far too late. The Germans decided to ignore the American protests and take their chance. After all, Jutland and their failure to gain victory on the Western Front had left them with no viable alternative.

There was a conviction that Britain could be driven out of the war rapidly by the heavy sinking of merchantmen. This reflected a belief that the submarines could achieve much, and that this achievement would have an obvious consequence. It was claimed that Britain would sue for peace on 1 August 1917. This represented an aspect of the total war also seen with the air assault on London in 1917 and the bombing of civilian targets.

The Entente merchant shipping losses to submarines grew rapidly: 464,599 tons in February; 507,001 in March; and a stunning 834,549 tons sunk in April. This was a catastrophic level of loss that could not be endured for long. If it carried on at this rate it would threaten not only foodstuff provision and the importation of other essential goods to Britain, but also the huge quantities of war materials and munitions required for the war being waged on the Western Front. Although the rate of U-boat sinkings had accelerated, it was still well below the rate at which the German shipyards were churning out new submarines.

Many German submarine enthusiasts assumed that their force would be able to seriously impede the movement of American troops to Europe, which was an aspect of a more general failure to appreciate American strength. Eduard von Capelle, the German secretary of state for the navy, unwisely told the budget committee of the Reichstag that, from a military point of view, America was as nothing. Aside from overestimating German and underestimating Anglo-American capabilities, notably the military consequences of economic power, there was a failure to understand the ability of Britain and America to respond and adapt.

The Americans were incensed at the resumption of unrestricted submarine warfare and almost immediately severed diplomatic relations with Imperial Germany. Britain then fanned the flames of heightened American emotions by releasing the text of an ill-judged telegram from the State Secretary for Foreign Affairs, Arthur Zimmermann, dispatched in January 1917 to his Ambassador in Mexico, proposing an alliance between Mexico and Germany.

The message was intercepted and decoded by the cryptologists of Room 40, after which the British cheerfully passed on the contents to the Americans: ‘We intend to begin on the first of February unrestricted submarine warfare. We shall endeavor in spite of this to keep the United States of America neutral. In the event of this not succeeding, we make Mexico a proposal of alliance on the following basis: make war together, make peace together, generous financial support and an understanding on our part that Mexico is to reconquer the lost territory in Texas, New Mexico and Arizona.’ (State Secretary for Foreign Affairs Arthur Zimmermann)

In 1914, there was active hostility in America to the idea of participation in the European war, a war that was presented as a struggle of the ‘old world’. However, the unrestricted submarine warfare that sank American ships ensured that many, if not most, Americans became persuaded of the dangerous consequences of German strength and ambitions, and did so in a highly moralized form that encouraged large-scale commitment. Thus, America constructed national interest in terms of the freedom of international trade from unrestricted submarine warfare. The alternative of limiting trade was not pursued.

The American reaction was predictable. The United States declared war on Germany. The potential addition of several American dreadnoughts to the Grand Fleet merely emphasised the hopelessness of any ideas the High Seas Fleet might have of openly contesting British naval supremacy. But the Americans also brought the promise of an increased number of destroyers to fight the submarine war, while their booming shipbuilding industry would ultimately help replace lost Entente merchant tonnage.

In a speech to Congress, President Woodrow Wilson used the crass offer as a battering ram to subdue any remaining anti-war elements within the United States, while also claiming the moral high ground: ‘With a profound sense of the solemn and even tragical character of the step I am taking and of the grave responsibilities which it involves, but in unhesitating obedience to what I deem my constitutional duty, I advise that the Congress declare the recent course of the Imperial German Government to be in fact nothing less than war against the government and people of the United States; that it formally accept the status of belligerent which has thus been thrust upon it; and that it take immediate steps not only to put the country in a more thorough state of defense but also to exert all its power and employ all its resources to bring the Government of the German Empire to terms and end the war.’

German shipping that had been trapped in American harbors on the outbreak of war was immediately confiscated, thereby changing sides overnight. And of course the Royal Navy no longer had to deal with American susceptibilities in enforcing the blockade of Germany. It was true that on land the American troops would not be able to make their presence felt until deep into the summer of 1918, but it was at sea that the Germans were trying to win the war in 1917.

For the British, victory in the prewar naval race was followed by victory in a wartime naval race that attracted, and has continued to attract, less attention. This is not surprising given that prewar building rates prefigured the outcome. Thus, the Germans were not able to fall back upon a margin of success in a large-scale shipbuilding program.

In part due to the dominance of the army’s needs, and certainly compared to the grip of the British Admiralty over wartime procurement, the Germans added fewer battleships and battlecruisers during the war than the British (four and three compared to fourteen and five). For example, the battleship Valiant, which fought at Jutland, had been completed earlier that year on the Clyde. This contrast ensured that the pronounced British numerical superiority of 1914 was greatly expanded.

The Germans did not have the prospect of support from new allies as the British did. In 1917, America had the third-largest navy in the world after Britain and Germany, and the Navy Act of 1916 had increased the shipbuilding program, although it had not yet come to fruition. Before 1915 Italy was the European neutral with the largest fleet. Portugal, which also joined the Entente, had a modest fleet. Brazil, which also suffered from the unrestricted German submarine warfare, followed America by declaring war in October 1917, but the small squadron it eventually dispatched did not see active service.

The Entente attempted to block U-boats in the Adriatic by establishing a barrier from Otranto in Italy across to the Dalmatian coast. Austro-Hungarian Captain Miklos Horthy planned a raid using three light cruisers, Novara, Helgoland, and Saida. Leaving the port of Cattaro at nightfall the cruisers reached the barrage and steamed along, blowing hapless Entente trawlers out of the water. Two accompanying destroyers sank an Italian munitions ship and its destroyer escort. The Entente subsequently abandoned night patrols by trawlers on the barrage.

Consisting of trawlers with steel ‘indicator nets’ to detect and entangle submarines and minefields, the Otranto Barrage was not especially successful, but the anti-submarine trawlers did present a tempting target for raids by Austrian destroyers.

Dartmouth and two destroyers succeeded in pounding Novara to a standstill and Horthy was badly injured. He survived to become an admiral and, eventually, dictator of Hungary.

Heading for home, the Austro-Hungarians were pursued by an force including the cruisers Dartmouth and Bristol. But reports of the approach of a stronger Austrian force led the Entente to break off the action. On the way back to Brindisi, Dartmouth was badly damaged by the lurking submarine U-25 and a destroyer was sunk by a mine. Saida towed the crippled Novara back to Cattaro.

As First Sea Lord at the Admiralty, John Jellicoe now became the man responsible for devising a solution to the U-boat menace in 1917. The on-off nature of the campaign had hitherto prevented the Admiralty from developing a coherent policy, so it was reliant on a fairly random combination of ad hoc measures, including endlessly patrolling warships, minefield barrage nets, the arming of more and more merchantmen and the unpleasant ruse de guerre of the Q-ship.

The most effective anti-submarine weapon currently developed was the depth charge which could be detonated by a hydrostatic pistol at the estimated depth of the intended U-boat prey. They contained some 300 pounds of high explosives, but tests had shown that they could not destroy a submarine unless they went off within 14 feet of it. However, if it exploded within 28 feet, it would probably cause enough damage to force the submarine to surface, where she could be swiftly dealt with by ramming or gunfire.

In December 1916 the ever-methodical Jellicoe had established an Anti-Submarine Division at the Admiralty to examine and co-ordinate the British response to the threat. Unfortunately, that was as far as his inspiration seems to have taken him. Jellicoe had always been a details man, marked by an inability to delegate even mundane matters.

What was needed was a method of determining with a fair degree of accuracy both the location and depth of a submarine. Yet here technology lagged well behind need, as there was still no effective way of tracking a submarine’s movements once it had submerged, except by honest guesswork.

Hydrophones that could pick up the noise of the submarine propeller or engines were found to be almost useless, as all they did was indicate the likely presence of a U-boat without giving any idea of its direction or depth. Worse still, they required the ship employing them to stop still in the water, otherwise the hydrophone would merely pick up the sound of its own engines; yet stopping was clearly a risky strategy in the presence of a U-boat.

Although Jellicoe was correct in his belief that there was no single answer to the U-boat problem, at the same time it should have been evident that a very important component of any solution would be the introduction of a convoy system as employed by Britain in war since time immemorial. If introduced, such a system would at a stroke have cleared the seas of helpless victims. Even if a submarine had located a convoy, it would have been exposing itself to attack from the escort. Jellicoe feared that such a solution would create yet more problems.

Jellicoe blanched at the sheer complexity of the administrative arrangements required to organize thousands of ships into convoys, pointing to the shortage of suitable escort vessels. He also dreaded the carnage that would result should they run into a minefield; he fretted over the practical problems of maintaining convoy speed and of co-ordinating the zigzagging courses of ships of vastly different capabilities. Underneath it all he had the lurking fear that a convoy would merely gather together potential victims for an orgy of destruction should the U-boats get among them.

Convoys had been successfully employed right from the start of the war for troop transports, but it was argued that they were effective because they were composed of the very finest merchantmen and liners with highly experienced crews capable of operating with military precision.

The pressure to introduce convoys continued to grow, receiving further impetus with a successful experiment for the Scandinavian trade which dramatically reduced losses. Still, the arguments continued as this was just one of several major sea routes. Many at the Admiralty rejected the idea of organizing all the sea routes into a comprehensive convoy system but, in the event, the losses suffered in April 1917 were such that by the end of the month it was belatedly decided to give convoys a proper trial.

The first experimental convoys proved a great success with none of the anticipated problems in station-keeping. But the introduction of a fully fledged convoy system was very slow, and shipping losses remained high throughout the summer of 1917. Jellicoe was still swamped by the real or imagined practical difficulties of the convoy system and so felt no urgency in addressing the implementation of the policy. Gradually the rate at which Entente shipping was being sunk began to fall in direct proportion to the number of ships travelling in convoy; at the same time the numbers of U-boats sunk began to rise.

The slow introduction of convoys was indeed a complex matter, demanding both a huge organizational effort and a steep learning curve for everyone concerned. The civilian crews of merchant navy vessels had to familiarize themselves with new working methods and accept the requirement for constant vigilance if they were not to be involved in a collision or lose touch with the convoy – especially when steaming without lights at night. Most coped better than the Admiralty had ever dreamed possible.

‘Convoy has added many new duties to the sum of our activities when at sea. Signals have assumed an importance in the navigation. The flutter of a single flag may set us off on a new course at any minute of the day. Failure to read a hoist correctly may result in instant collision with a sister ship. We have need of all eyes on the bridge to keep apace with the orders of the commodore. In station-keeping we are brought to the practice of a branch of seamanship with which not many of us were familiar. Steaming independently, we had only one order for the engineer when we had dropped the pilot. “Full speed ahead!” we said, and rang a triple jangle of the telegraph to let the engineer on watch know that there would be no more “backing and filling” – and that he could now nip into the stokehold to see to the state of the fires. Gone – our easy ways! We have now to keep close watch on the guide-ship and fret the engineer to adjustments of the speed that keep him permanently at the levers. The fires may clag and grey down through unskillful stoking – the steam go “back” without warning: ever and on, he has to jump to the gaping mouth of the voicetube, “Whit? Two revolutions? Ach! Ah cannae gi’ her any mair!” but he does! Slowly perhaps, but surely, as he coaxes steam from the errant stokers, we draw ahead and regain our place in the line. No small measure of the success of convoy is built up in the engine-rooms of our mercantile fleets.’ (Captain David Bone, SS Cameronia)

There was a further boon as the convoys also allowed a more effective use of the naval intelligence still pouring in from Room 40 and the wireless directional stations. This provided a wealth of information as to the approximate location of German submarines which seemed to have no concept of wireless silence. Although too geographically vague to be of much use for the multifarious patrols engaged in the generally fruitless task of tracking down and sinking U-boats, it did greatly assist convoys as they could be diverted round the dangerous waters where U-boats were known to be operating.

Even as early as August 1917, Lieutenant Commander Alfred Saalwächter commanding the U-94 realized the impact of the new system: ‘The convoys, with their strong and efficient escorts making an attack extremely difficult, are in my view quite capable of drastically reducing shipping losses. The chances of sighting a convoy of seven ships is less than that of sighting seven independent ships. In the case of a convoy it is mostly possible to only fire on one ship. For any ship torpedoed in convoy, the chance of immediate help is a factor of considerable importance to morale.’

When they did encounter a convoy, the submarine commanders were forced to take excessive risks to score their kills, all the while harried by armed escorts and liberally bespattered with depth charges. The log book kept by Lieutenant Commander Hans Adam of the U-82 reveals the chances that had to be taken and difficulties surmounted to make a successful attack on a convoy in September 1917: ‘I shot past the bows of this steamer towards Steamers 4 and 5. Steamer 4 I hit. Steamer 2 had hoisted a red flag, which was probably to announce the presence of the U-boat; for several torpedo boats make for the steamer. As there was no chance of firing from the only remaining usable tube (stern tube), I dived. The destroyers dropped about ten depth charges; one burst pretty near the stern. The attack was rendered very difficult by the bad weather, swell, seaway and rain squalls. The success of the attack was due to the excellent steering under water. Made off noiselessly south-east under water. 4.45 pm rose to surface. I try to come up with the convoy again, as it is still to be seen. But a destroyer forces me under water again. 6.37 pm rose to surface. Two destroyers prevent me from steaming up. Owing to heavy seas from south-east it is impossible to proceed south so as to get ahead of them. Moreover, sea and swell make it impossible to fire a torpedo. Therefore gave up pursuit.’

Convoying owed much to American support. Although they lacked experience in anti-submarine warfare, the Americans deployed their fleet to help protect communication routes across the Atlantic. From May 1917, American warships took part in anti-submarine patrols in European waters, initially with six destroyers based in Queenstown in southern Ireland where Admiral Sir Lewis Bayley, the British commander, was a key figure in fostering Anglo-American cooperation.

The resourceful Vice Admiral William Sims, commander of American naval forces in European waters, was important in encouraging convoying. To assist convoying in the Mediterranean, American warships were based in Gibraltar. American escort vessels rapidly contributed to the effectiveness of convoying, the key help being in destroyers. They were fast enough to track submarines and to keep them submerged, which reduced their effectiveness.

More generally, convoying was an aspect of the Entente’s global direction of most of the world’s shipping, trade, and troop flows. The Allied Maritime Transport Council oversaw an impressive system of international cooperation at sea, allocating shipping resources so that they could be employed most efficiently. This was important as an aspect of economic warfare and also in lessening targets for German submarines.

British merchant shipping provided close to half of France’s imports, which was a key aspect of the British maritime contribution to the war effort. British control of the shipping of neutral Norway, which was unable to protect its shipping, increased greatly as a result of the new German policy, and Norway’s ships were transferred to the British flag.

Command and control was a key area of naval operations that benefited greatly from technological improvement. Developments with radio made it easier to retain detailed operational control. Directional wireless equipment aided location and navigation and was employed to hunt German submarines by triangulation, while radio transmissions changed from a spark method to a continuous wave system.

Submarines had an inherent operational disadvantage in that it was not necessary to sink the submarine but only to have shipping come safely home. This was a weakness appreciated during the next war when air cover forced U-boats to submerge and allowed convoys to outrun them. Nevertheless, it was also important to weaken the submarine force by sinking boats, killing crew, and weakening morale. Thanks to the tracking of submarine movements, the British acquired an edge. However, there was not yet any equivalent to the sonar used in the Second World War, and this affected the level of submarine losses.

There were also improvements in navigational skills, such that it was possible to cross one’s own minefields more successfully. The British also made valuable advances in firing depth charges.

Alongside incremental improvement, there were limitations. Aircraft were not yet able to make a fundamental contribution to anti-submarine operations because key specifications which they had by the Second World War were lacking during the Great War. Moreover, the anti-submarine weapons dropped by aircraft were fairly unsophisticated compared to those of the Second World War.

A dull pessimism began to color Jellicoe’s whole outlook on the war. This showed itself most clearly in a controversy over the measures required to destroy or render useless the German destroyer and submarine bases established in the Belgian ports of Zeebrugge and Ostend. At a meeting to discuss the matter, Jellicoe said that Britain would not have the necessary supplies to continue the war into 1918, an opinion shared by no one else. Douglas Haig, the commander of the BEF, reactated very strongly, condemning Jellicoe for his defeatist attitude.

Jellicoe had correctly pointed out the impossibility of achieving anything worthwhile using long-range naval bombardments, and he had become convinced that the Army must assist in clearing the north Belgian coast before the winter of 1917 brought an end to the campaigning season. This was not so controversial in itself, but Haig was an aghast spectator when Jellicoe made an ill-judged intervention at a meeting of the War Policy Committee. He was speaking in support of Haig’s planned Flanders offensive, but his line of reasoning went well beyond acceptable limits: ‘A most serious and startling situation was disclosed today. At today’s conference, Admiral Jellicoe, as First Sea Lord, stated that owing to the great shortage of shipping due to German submarines it would be impossible for Great Britain to continue the war in 1918. This was a bombshell for the Cabinet and all present. A full enquiry is to be made as to the real facts on which this opinion of the Naval Authorities is based. No one present shared Jellicoe’s view, and all seemed satisfied that the food reserves in Great Britain are adequate. Jellicoe’s words were, “There is no use discussing plans for next spring – we cannot go on!”’ (Field Marshal Sir Douglas Haig, General Headquarters, BEF)

Haig was characteristically blunt in his overall appraisal of Jellicoe: ‘I am afraid he does not impress me – indeed, he strikes me as being an old woman!’ Haig was being a little unfair to a naval commander who was hampered by the effects of chronic fatigue caused by his own devoted service to his country in positions of the highest responsibility throughout the war. But, in essence, Haig was right: the diminished power of Jellicoe’s decision-making had made him a liability.

Jellicoe still had the complete support of the First Lord of the Admiralty, Lord Carson, but the new Prime Minister, David Lloyd George, ever the consummate politician, ‘promoted’ Carson into the War Cabinet and appointed the vigorous former industrialist Sir Eric Geddes in his stead. The amateur naval man Geddes would in fact bring a thorough professionalism to the Admiralty, reorganizing the function of the Sea Lords and the Admiralty staff to increase performance at all levels of the administration. Jellicoe was left exposed and knew that he was next in the Prime Minister’s sights.

Almost despite itself, the Admiralty had stumbled across the solution to the submarine crisis. Nevertheless, it was all too late, for Jellicoe would finally be dismissed by Geddes. The new First Sea Lord, Vice Admiral Sir Rosslyn Wemyss, had a far greater residual energy and was able to build on the sure foundations that Jellicoe had laid.

Wemyss would continue Jellicoe’s reforms within the Admiralty, building a logical staff structure that allowed the proper delegation of decisions and responsibility.

By the end of 1917 one of the great questions of the war had been answered: Britain would not after all be starved out. The failure of their submarines to achieve their ambitious targets resulted in a severe blow to German morale, and the German High Command realized that the war would not be won by the U-boats.

The Battle of Jutland, a year earlier, had confirmed that the British blockade of Germany would endure. The 1917 defeat of the U-boats, however, would ultimately result in the 1918 Spring Offensives designed to knock Britain out of the war on land before the Americans could arrive in strength on the Western Front.