Apart from the human element in the Great War, which was predictably unpredictable and infinitely variable, possibly the most dominant material features were: the artillery shell, barbed wire, the machine gun, toxic gas, the trench system and the U-boat.

Before the Great War began, it was generally supposed that the clash of the British and German fleets of warships would be one of the deciding factors in ending the war. Although both major and minor clashes of warships at sea did take place, they were by no means conclusive in themselves, despite the quick elimination of Germany's maritime colonies across the world and their associated 'colonial' warships. What these sea-battles did do, from the British viewpoint, was to materially affect the land war. They permitted the outstanding maintenance of the efficacy of the British naval blockade on the German ports and the keeping open of the Empire's sea-lanes for the transport of men, raw materials, foodstuffs and supplies.

A highly important factor, as far as the war-at-sea was concerned, was the emergence of the state of unconditional warfare that was waged by the German submarine fleet on the mercantile marine of both the combattant and neutral nations - the so-called U-boat menace. At certain stages of the war, this threat was so grave that it threatened the ability of Great Britain to feed and supply itself and its army. In January 1917, a progressive process of food rationing began with the issuing of the first of six orders that became more extensive, restrictive and inclusive as the months passed.

Accordingly, doubts were soon cast whether it would be possible for the British to continue to participate in the prosecution of the war to the degree necessary to achieve ultimate victory over the Central Powers (Germany/Austria-Hungary, Turkey and Bulgaria). Although the French and the Americans were committed to the war, it was by no means certain that they would have continued with the war if the British were not able pull their full weight.

The status of the submarine in 1914

It was largely the work of the American naval designer J.P. Holland that influenced the European production of submarines prior to the Great War. He introduced the system of double hull construction and its associated technique of pumping of air between these hulls to control buoyancy and trim.

When the war broke out in 1914, both Britain and Germany had such submarines with large diesel engines in service, some with long range capability - 6 to 7,000km.

Whilst both the British and German submarines were quite rudimentary in performance - slow, limited diving duration and structurally fragile - they were seen by most military analysts as a potential threat to the large warships of the day. Although these submarines did not have any deck guns, the potential of the torpedo was well recognised. By 1914 the torpedo had a maximum range of over 10,000 metres, but in practice it was accurate at only around 1,000 metres. German torpedoes were consistently superior to those of the Allies throughout the war.

Of the belligerent nations, the French had, in 1914, by far the biggest fleet of submarines - 123 - but their operational utility was strictly limited and many were still driven by steam power with all the operational problems that entailed.

The German name for the submarine was Unterseeboot. They were designated as U-1, U-2 and so on. It was the British Sea Lord, Winston Spencer Churchill, who coined the sobriquet U-boat. A suffix letter after the 'U' (e.g. B or C) indicated a different type of submarine other than the offensive patrol submarine - the classic U-boat.

The deployment of the submarine was seen as being both in defence and offence. In particular against ships involved in the British economic blockade, but also for attacking ports and land installations; though many military figures of the day considered that to use submarines to attack ships on the open sea was unequivocally unethical.

All in all, whilst all navies had their submarine enthusiasts, particularly for better long range versions, the consensus before the war was that additional submarine construction was not an immediate high priority.

The submarine goes to war

Once the war began, both the British and the Germans saw the potential of the submarine amply demonstrated by the immediate sinking of large British warships at anchor, in the North Sea and in the Channel. These successes were the prime cause of the British Fleets withdrawing, at least temporarily, into safer waters in the Irish Sea and at Scapa Flow in the far north of Scotland.

As a direct result of these early German successes, crash programmes of submarine development and production were universally put in train.

In the event, the anticipated spectacular success by submarines against large warships largely eluded both Navies, although numbers of significant warships continued to be sunk throughout the war - the British pre-Dreadnought HMS Britannia fell victim to a torpedo as late as the 10th November 1918.

The true role of the German U-boat eventually emerged as that of a killer, or raider, of commercial transport ships, particularly those plying the British Empire's sea-lanes and crossing the north Atlantic.

The rise of the commercial raider U-boat

From a slow start in August 1914 - the Germans only had 10 of their long-range diesel submarines serviceable - the Germans rapidly built up their submarine fleet by concentrating on relatively few different types. These were capable of being suitably modified for special purposes. They also employed industrial type production schedules. Where appropriate, new technology was introduced even during the production phase.

In all, 134 U-boats became operational during the hostilities, with many more in the production or the planning stage when the war ended. Throughout the war the Germans put great efforts into making the boats more sea-worthy, more comfortable for the crew, quicker when travelling both on the surface and submerged, and supplied them with ever more efficient torpedoes. These improvements were greatly needed, as the operational availability was very low: at any one time only one third of the U-boats (and Allied submarines) were at sea.

Of particular relevance to the campaign against surface shipping, was the fitting of more effective surface guns to all the new U-boats; eventually fast firing guns of calibre up to 150mm were installed.

Once the pattern of the deployment of the submarines crystallised, the Germans put a large proportion of their U-boats into the campaign against merchant shipping along the Allies' sea-routes: the later versions of the U-boat were mainly designed with this specific role in mind.

At the outset the U-boat crews obeyed the code of the sea and the so-called 'Prize Rules. This required the submarine to surface, to hail the suspect ship to order it to stop, and to send aboard a search party. If suspicions about the origin of the ship and/or its cargo were confirmed, the ship's crew were permitted to take to their boats unhindered. Once the victim's lifeboats were clear, the submarine sank the ship with a torpedo or, more often, with surface gunfire. Smaller ships were often scuttled, or sank with judiciously placed explosive charges.

As the U-boat only had a very limited supply of torpedoes, these were usually reserved for naval targets.

Other U-boat types

Apart from the long-range diesel U-boats, the Germans developed two other ranges of U-boats, the UB and UC -boats. These were, respectively, smaller and simpler and submarines for coastal defence and, somewhat larger, prefabricated, submarine minelayers.

Both of these submarines ran to three Classes (I - III) and were numbered respectively, UB-1 to 132 and UC-1 to 105UC-90 to 105 were never operational. although the UC Class III boats

Additionally, several of the super large German Deutschland Class long-range U-boats were converted to what were known as U-cruisers that were specifically intended to attack on the surface Allied merchant shipping across the Seven Seas. They carried the huge 155mm-deck gun that could out-shoot and out-range the surface armament of most of its rivals; even those carried on quite large warships. These U-cruisers bore the numbers U-151 to 157.

The U-boat campaign
From the outset of the war the attitude of the German High Command vacillated between wanting to follow the rules of the sea but at the same time aiming to create the utmost devastation of the huge Allied mercantile marine. For it was upon these transport and cargo ships that the British and its allies relied for the transport of the material needed for the prosecution of the war, and the feeding of the British nation and its army. Without the ceaseless input of the material required at home and abroad, the flow of munitions and armaments to the Western Front factories and the food required to feed the civilians and military would dry up, and the Cause would be lost.

The Germans quickly discovered that the problems of following the Rules Of the Sea and the coverage of the vast reaches of the oceans, where the mercantile navies plied their trade, were almost impossible to reconcile.

Steps down the road towards Unrestricted Submarine Warfare
The German High Command in its frustration, turned to harsher, illegal methods. The rationale used to justify this action was that it was only a counter-blockade in reaction to the British Navy's own highly effective blockade of the German ports.

By the end of 1914, the Kaiser had come round to the way of thinking of the High Command and the politicians. He acquiesced to what amounted to a gamble, despite the realisation that reaction from all the sea-faring nations would be severe. As indeed it was. It was pointed out to the Germans, particularly forcibly by the Americans, that such an arbitrary action constituted a war crime. Inevitably, neutral shipping would be also inadvertently sunk.

The Germans ignored these protestations and appeals in the hope that decisive results at sea could be quickly achieved. Accordingly, on the 4th February 1915, the seas around Great Britain and Ireland were classified as a War Zone and U-boat commanders were given carte blanche to sink Allied shipping without the necessity of following the Prize Rules and Rules of the Sea. The ships of the Neutral trading nations would have to take their chances. Appeals by the United States of America to the Kaiser caused a delay for a few days in its widespread application, but gradually the principle was applied with few restrictions or limitation.

Thus began a trial of strength between the U-boats and the Allied navies in what was the first of three episodes of unrestricted submarine warfare, each one more blatant and destructive than the former. In March 1915 a rotating operational force of six U-boats sank 85,000 tons of Allied shipping.

The early U-boat toll and its consequences

Whilst the toll of the U-boats escalated rapidly, with over 100,000 tons of Allied cargo ships being lost in each of the months of May to July 1915, there was also a toll on the U-boats themselves. A total of four U-boats were lost in April 1915, and another three in the period May to July 1915.

However, the impact of the Allied commercial shipping losses paled in significance alongside of the sinking, in May and August 1915 respectively, of the passenger liners, the Lusitania and the Arabic. There was great loss of life, including many Americans.

Although there were claims - subsequently justified - that both ships were carrying material useful to the war effort of the Allies, the vociferous worldwide outcry that these atrocities invoked panicked the Kaiser and the German Establishment.

On the 1st September 1915 the first episode of unrestricted submarine warfare 1915 was suspended.

On the 25th November 1915, the German Navy issued a new secret order stipulating the restrictions that applied to U-boat attacks on passenger liners. Nevertheless, by the end of 1915, the total of British shipping sunk had risen to 4% of the total British mercantile tonnage. For the Germans, it was by no means the hoped for crippling toll, but it was worrying enough, if not critical, for the British.

From the German side, only a relatively low number of 12 U-boats had been lost, giving hopes that a decisive breakthrough was still possible.

<>As a result of these setbacks, the focus of German submarine warfare was shifted to the Mediterranean and to the Allied landings in the Dardenelles and Salonika, with some success: 58 Allied vessels were sunk in this theatre of war by the end of 1915.

New regimes, new rules, same objective

In early 1916, with the almost doubling of the operational U-boat strength, the good intentions of Germans began to weaken. The new Commander in Chief of the High Seas Fleet - Admiral Reinhardt Scheer - expressed a wish for the renewal of unrestricted submarine warfare. He was confident that the German Navy had the wherewithal to achieve a quick and decisive result in the Handelkrieg = Trade War.

The Germans hatched what amounted to an ultimatum. Unless the Royal Navy relaxed its blockade of German ports within two weeks, a degree of unrestricted submarine warfare would be recommenced. Obviously, from the outset, there was not a shadow of a hope that the British would give up what they considered to be one of their most effective war-ending measures - as Scheer probably well understood. So, on the 15th March 1916, the U-boat attacks began once again. The new orders issued to the U-boat commanders were imprecise - perhaps deliberately so - and were applied at sea with various degrees of vigour.

The outcome of this confusion was readily foreseeable. On the 24th March 1916, a French cross-channel ferry - the Sussex - was lost with some loss of civilian lives, including Americans. In response, the Germans announced on the 20th April 1916, another suspension of unrestricted submarine warfare. In the interim another 250,000 tons of Allied ships had been lost.

The reaction of Admiral Scheer was to intensify mine-laying by the considerable fleet of specialist U-boats that had been built expressly for this purpose. Scheer had no intention of risking his attack U-boats under the Law of the Sea Prize Rules. Meanwhile the Mediterranean U-boat Campaign brought the Germans rich pickings with small losses.

In the Autumn of 1916, another change in regime took place when the Third Supreme Command took control of both the German Army and Navy. In secret, the German Navy was allowed to undertake a limited degree of unrestricted warfare, with the understanding that total unrestricted submarine warfare would follow when a flotilla of new submarines was ready for operations at sea.

Various peace overtures by German politicians were unsuccessful

Accordingly, Scheer unleashed a flotilla of over 70 U-boats (out of a total of 110 of all types) in another bout of partially unrestricted submarine warfare. This produced in the later part of 1916/early 1917, a monthly toll of 300,000 tons of British shipping alone. Then, the final restraints were removed by Scheer, with the openly acclaimed support of the military, politicians and the German people. This was the third and final episode of the U-boat war.

Britain put at bay by the U-boat threat
In late 1916 and early 1917, the alarm bells really began to ring in Whitehall about the effect of the U-boat campaign on the present and future British war effort. Serious discussions were entered into concerning the introduction of anti-U-boat countermeasures, among which was the long touted Convoy System. In this scenario, merchant ships would travel over U-boat infested waters in a tightly controlled flotilla protected by a constant shield of fast warships.

In 1917, the U-boat war grew more intense, with 40 U-boats on patrol at any time. The average monthly tonnage of Allied ships sunk approached half a million, despite some success with the convoy system.

The worse British scenarios of 1916 about a supply shortage came closer to reality. In the months of April, May, and June 1917, over 2 million tons of Allied shipping was lost. Neutral nations were reluctant to put their ships to sea and 300 remained in port worldwide.

British Naval Intelligence reports indicated something like another 100 (in the event 80) new U-boats would come into service during 1917. Crisis loomed for the British war effort. However, good sense prevailed, and an extra effort was put into making the convoy system work.

On April 27th 1917, the British Admiralty formally authorised the large-scale use of the convoy system. In a complementary move, the Eastern sea traffic was diverted away from the vulnerable Mediterranean and the Suez Canal sea-lanes, despite the increased transit periods and shipping costs that were involved. Still, it seemed touch and go whether the convoy system would be able to contain the U-boat threat before the American contribution made a successful outcome to the war more certain.

The following months of 1917 saw a seesawing of the success of the U-boats - particularly the long range U-cruiser boats - against their losses due to anti-submarine measures by the Allies. Somehow, Britain managed to maintain its war economy throughout 1917. The Germans had badly miscalculated, or even gambled upon, both their own capabilities and the inability of the British to adapt to the changing circumstance, to enhance and husband their indigenous food resources and to introduce new and effective anti-submarine strategy and technology. The big German gamble had not paid off, although their submarine crews had certainly fought manfully and done their best.

It was not until the middle of 1918 that a distinct trend developed whereby, for the first time, the U-boat losses rose to about 14 per month - although replacements were still about equal to the losses - whilst the loss of Allied ships travelling in convoy declined to less than 1%

Other critical factors in the prosecution of the war at sea were the increased use of anti-submarine aircraft patrols by the Allies, and the increased efficacy of the Dover barrage. This made the English Channel a no-go area for the U-boat flotillas. Also the Northern Barrage, maintained mainly by the Canadians and Americans, made it much more difficult for the U-boats to use the British Western Approaches. Life was getting harder for even the most experienced U-boat captains and crews. Even the event of the 'Wolf-pack' strategy (numbers of U-boats working in concert) failed to improve the ratio of kills of the operational U-boats.

By August 1918 a total of 150 U-boats of all types had been lost, many along with the most experienced captains and crews.

In September 1918, there were clear indications that the Convoy System in the Atlantic, Mediterranean and elsewhere was beginning to bear fruit. Whilst it would have been a foolish mariner who assumed the U-boats had been beaten, stalemate would have been a fairer evaluation of the situation at the time.

The German commanders made a final throw of the dice when in October they recalled all the submarines engaged in the Handelkreig to launch a last ditch foray against the British Grand Fleet. But although the U-boat submariners did not participate in the Kiel naval base mutiny, the disorganisation it caused meant the attack on the British Fleet was aborted before it had begun.

Almost beyond belief, 224 new U-boats were under construction as late as October 1918, when the Germans decided to halt all submarine activity - at the demand of the US - to better to pursue terms for an Armistice. What an effect all these new U-boat would have had if the war had gone on into 1919 can only be conjectured.

The overall toll of the U-boat Campaign

In terms of the commitment of men and material, the U-boat Campaign was not really significant in the grand scheme of things in the Great War; certainly not in comparison with the huge investments in the surface fleets of both navies or the land forces. But its practical and psychological effect was enormous. On its outcome of the German Submarine Campaign truly rested the fates of nations and the world order.

At its maximum strength at sea of 61 U-boats at any time, the German Navy never had enough U-boats to overwhelm the Allies sea defences and bring to a complete halt the ceaseless flow of men and material through the sea-lanes of the Seven Seas.

At the end of the war, the losses of U-boats, sunk or interned, totalled 192, with more than 5,000 officers and men killed. By the nature of their war, the number of wounded U-boat crew who survived was very small compared with their landlubber comrades. Most crews went down with their submarine, or were cast into the open sea with little hope of rescue.

Was there a star, or ace, U-boat, captain and crew? Most observers would have little difficulty in accepting the nomination of U-34, commanded by Kapitan Johannes Klasing. During its tours of duty from 1914 until 1918, U-34 was recorded as having sunk a total of 170,000 tons of Allied shipping. This represented something like 55 ships). U-34 was the last U-boat sunk. Whilst transiting the Straits of Gibraltar on the 9th November 1918 it finally succumbed with all its crew to shelling and depth charging by an anti-submarine Q-ship, HMS Privet.

To avoid their U-boats falling into Allied hands, the crews of 3 UB- and 1 UC-boats based in Flanders and 4 U-, 2 UB- and 4 UC-boats based in the Adriatic, respectively destroyed their U-boats in October and November 1918.


Arthur Wellesley, The Duke of Wellington, after the Battle of Waterloo in 1815, described the battle as 'A close run thing'. This observation could be equally applied to the Submarine War, 1914-18. Until the very end the outcome was never certain either way. And had those extra 200 U-boats become operational in early 1918, the outcome could easily have been different.

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