Günther Prien and U-47: The Bull of Scapa Flow: From the Sinking of HMS Royal Oak to the Battle of the Atlantic

By Dougie Martindale

On the night of 13/14 October 1939, the Type VIIB U-boat U-47, on its second War Patrol, penetrated the main Royal Navy base at Scapa Flow and sank the British battleship HMS Royal Oak. This legendary attack is remembered as one of the most audacious raids in the history of submarine warfare.

Laid down on 25 February 1937, and entering service in December 1938 under the command of Oberleutnant zur See, later Kapitänleutnant Günther Prien, after sinking HMS Royal Oak both Prien and his famous U-boat were known thereafter as ‘The Bull of Scapa Flow’. During a lavish celebration in Berlin to mark the sinking of HMS Royal Oak, the crew members of U-47 were received by Adolf Hitler. For his part, Prien received the Knight’s Cross, becoming the first U-boat officer and only the second member of the Kriegsmarine to receive this decoration.

Still under Prien’s command, U-47 returned to sea on 16 November 1939. Over the months that followed, U-47 went on to complete a total of ten war patrols. During these, Prien and his crew sank a total of thirty-one Allied ships and damaged eight more, making it one of the most successful U-boats of the Second World War.

As a central figure in the Battle of the Atlantic, Prien was consistently at the heart of events until he was lost on board U-47 in March 1941. U-47 had departed Lorient on her tenth and last patrol on 20 February 1941. She went missing on 7 March 1941.

In this remarkably detailed account, the author charts the full story of U-47, its commander and crew. As well as examining all the main events in each of U-47’s ten War Patrols, particularly the attack on HMS Royal Oak, for which a number of important new conclusions are explored, as is U-47’s final fate.

• Language: English
• Publisher: Pen and Sword
• Release date: Sep 30, 2018
• ISBN: 9781526737762

Dougie Martindale

Dougie Martindale Is The Author Of Fifteen Articles Which Primarily Focus On The Modifications Made To German U-Boats And The Paint Colours. Ten Articles Have Been Translated Into Spanish And Six Were Published In The _Subcommittee Report_ Magazine. He Is Co-Owner Of Accurate Model Parts, A Company Producing Aftermarket Products For Submarine Models. He Has Also Completed Books On Scottish Aircraft Wrecks And Cycle Touring. Dougie Lives In The West Of Scotland With His Wife And Daughter.

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Part I

Introduction – The Battle of the Atlantic

Before we begin our study of U-47 , it is necessary to provide an overview of the Battle of the Atlantic so that readers can appreciate the environment in which the boat operated.

Karl Dönitz

The most important figure on the German side of the Battle of the Atlantic was Admiral Karl Dönitz. As the Befehlshaber der Unterseeboote (BdU – Commander-In-Chief of U-boats) he was a pivotal character, overseeing the development, tactics and policies of the U-bootwaffe (the U-boat arm) of the Kriegsmarine (German Navy) from 1935 until 1945. It was under his leadership that his commanders would flourish and ultimately perish.

Karl Dönitz gained valuable experience as a U-boat commander in the First World War. Initially he served in the surface fleet but in 1917 he served as a watch officer on U-39, a very successful U-boat which sank no fewer than 157 ships. During the course of several very effective patrols Dönitz soaked up experience and knowledge from his commanding officer, Walter Forstmann, who ranks as the second most successful commander of the First World War. In March 1918 Dönitz was given command of UC-25 and sank four ships during two Mediterranean patrols. Staying in this theatre, he then took command of UB-68 in September 1918. Only a week before the armistice took effect, he sank a straggler from a Malta-bound convoy. UB-68 then became uncontrollable, forcing Dönitz to expend all the compressed air. Unable to dive, and in the midst of a convoy, he had no choice but to abandon ship. The boat was scuttled and inevitably Dönitz was captured. Such wartime experience was invaluable in later years when he became head of the next generation of the German submarine force.

Prior to the Second World War

By the end of 1916 the U-boats of the Kaiserliche Marine had sunk in excess of 1,000 Allied ships. Some senior British figures feared at that time that the losses inflicted by U-boats would cause Great Britain to be unable to continue the war into 1918. Despite the serious reservations of high-ranking naval officers, the convoy system, in which a number of merchant ships sailed together under the protection of warships, was inaugurated in May 1917. Although the convoy system reduced the number of sinkings, the loss of tonnage per month remained serious and many ships were still being despatched to the bottom of the Atlantic by the predatory under-sea boats.

Nearly 5,000 merchant ships were sunk by German U-boats during the First World War. In the closing stages of the war anti-submarine measures had become relatively effective. This led to the British Admiralty (the body responsible for commanding the Royal Navy) in the inter-war period becoming complacent about the threat a renewed U-boat fleet might pose to the British merchant fleet. Part of their complacency resulted from their faith in Asdic (later named sonar), an underwater device mounted underneath a warship hull. Developed at the end of the first war, the system emitted sound waves which could be used to detect a submarine when the waves were reflected back to the warship. What British officers and Admiralty personnel overlooked was that U-boats of that vintage were essentially submersibles which primarily operated on the surface but had the capacity to submerge for short periods. Asdic could be used productively against submerged targets but not against those which remained on the surface, as would be the case with many U-boat attacks in the Second World War. Therefore the inter-war faith in Asdic neutralizing the threat of U-boats was misguided.

Following the end of the First World War Germany was bound by of the Treaty of Versailles. This peace settlement forced a number of territorial concessions, the payment of harsh financial reparations and strict restrictions over the size of her navy (now renamed as the Reichsmarine). A turbulent period of great economic hardship and unrest followed in Germany. There was significant resentment towards the treaty by German citizens, leading to a desire to reject the harsh impositions and regain lost territories. In 1935 Germany rejected the treaty and began to build up her armed forces in earnest.

Another event which took place in 1935 was that Dönitz, who had recently commanded the light cruiser Emden, was selected to guide the rebirth of the next generation of the U-boat arm – the U-bootwaffe. He set about his task with great vigour and professionalism. As a former U-boat commander he knew well the harsh living conditions on board submarines and that everyone, regardless of rank, had to live in close proximity to each other. The traditional rigid divide between officers and ratings in the surface fleet was not suitable for this type of working and living environment so he encouraged a less formal relationship between officers and their men.

Karl Dönitz was convinced that Germany would once again become embroiled in a war with Great Britain and that a large fleet of U-boats was essential. He had learned the lessons of the past conflict and developed a tactical doctrine that was suited towards a future tonnage war in the Atlantic. The U-bootwaffe was, in some ways, an extension of his tactical beliefs and personality and he was instrumental in directing the training of the men. But he remained at that time a relatively junior officer who had very limited influence in terms of overall naval strategy. Due to the Anglo-German Naval Agreement of 1935, Germany was limited to a certain level of tonnage that could be allocated to the building of submarines. The amount of tonnage increased over time but what remained constant was that Dönitz’s preferred option – the construction of as many medium-size Type VIIs as possible – was ignored in favour of a mix of small, medium and large U-boats. By the time the war started, not only was the U-bootwaffe much smaller than what was required for a war of this magnitude, but the mix of boat types was not what Dönitz wanted or required.

Hostilities Commence

In September 1939 Germany did not depend upon seaborne trade; oil could be sourced from their new ally, the Soviet Union, and iron ore could be bought from the relative proximity of Sweden. Great Britain, on the other hand, was an island nation which required supplies imported by sea from abroad. It was Dönitz’s unstinting belief that the best way to win a war against Britain was to cut this vital Atlantic lifeline and that U-boats rather than surface vessels were ideally suited for this purpose.

One factor which prevented this from becoming reality is that in the early war period the U-bootwaffe simply did not have enough U-boats to wage a successful tonnage war against Britain. Another factor was that the policy of unrestricted submarine warfare, in which submarines can sink all merchant ships without warning, was not implemented by Germany immediately. When Hitler invaded Poland his hope was that Britain and France would remain neutral, as they had done following the annexation of the Sudetenland and the marching of German troops into Czechoslovakia. Prize Rules were in effect in the early weeks of the war, not in relation to any humanitarian considerations, but in the hope that full-scale war with these nations could be avoided. But as the months passed the nations became further embroiled in conflict and hope of diplomatic settlement faded. The rules of engagement governing U-boats were progressively relaxed until the horror of full unrestricted submarine warfare became the norm.

At the start of the war the Royal Navy preferred to believe that U-boats could be sunk by ‘hunter-killer groups’ of warships. The loss of the aircraft carrier HMS Courageous on 17 September 1939, operating as part of a hunter-killer group, to U-29 in the opening month was a graphic illustration of how vulnerable these valuable assets were to the undersea menace. As well as the risk, it also became apparent that the dearth of resources and the enormity of the ocean meant it would be very difficult for the groups to find U-boats. Aircraft carriers and battleships were no longer risked in hunter-killer groups and it was decided that it would be more expedient to attack U-boats once they had spotted a convoy.

Introduced at a very early stage in the war, the convoy system was responsible for fewer sinkings for two main reasons. The first benefit resulted from the vastness of the ocean. If forty ships all sailed independently, the U-boats dotted around the ocean had a much greater chance of finding one or more of these ships. But if they were all herded into one narrow convoy, the possibility of all forty ships sneaking past the line of waiting U-boats was quite high. Indeed, finding convoys was much more difficult than might at first be appreciated. The lookouts on a conning tower could only see for a relatively short distance and this visibility was impaired by the poor weather which frequently disturbed the Atlantic sea lanes. The second benefit is that the convoys were protected by escorting warships, which could counter the attacking U-boats by driving them off or even sinking them.

The Wolfpack Concept

Dönitz’s strategy was the tonnage war, whereby a force of U-boats, surface vessels and aircraft would sink an amount of tonnage which exceeded that which the enemy could replace by new-build ships. To do this he sought the most efficient way to sink the maximum number of ships at minimum cost. His solution was to attack convoys in groups which came to be known as wolfpacks.

The concept for wolfpack operations started with U-boats patrolling the main shipping routes. The German radio monitoring service (B-Dienst) was very effective in decoding the merchant ship codes and would update BdU (Karl Dönitz and his operations base) with relevant information concerning convoy positions and courses. This valuable information allowed BdU to organize a line of boats in the hope that one of the lookouts on a U-boat would spot smoke on the horizon. When a convoy was spotted, the U-boat would shadow the convoy and regularly report to BdU by radio the course, speed and position so that Dönitz could organize for as many U-boats as possible to converge. When enough boats were collected around the convoy, the pack of wolves would all attack. This would preferably be conducted on the surface at night, where their small silhouettes would be very difficult to spot from the convoy.

The more primitive communication methods used during the First World War meant that German U-boats were not able to operate in groups during that conflict. However, the inter-war improvements in radio technology were exploited to good effect by the siting of radio masts along the French coast. In the autumn of 1940 the theory of wolfpack attacks was fully vindicated when devastating losses were incurred upon merchant convoys. At that time aces such as Engelbert Endrass (U-46), Günther Prien (U-47), Herbert Schultze (U-48), Otto Kretschmer (U-99) and Joachim Schepke (U-100) accomplished multiple sinkings in short time frames in their Type VIIB U-boats. Known personally to Dönitz, these very capable and highly-trained men were the elite of the new-born U-bootwaffe. The most aggressive commanders achieved more sinkings by moving inside the convoy lanes in the dark, and then shooting at very close range while remaining on the surface. Otto Kretschmer proved to be particularly deadly by developing his philosophy of one torpedo per ship, which permitted him to retain more torpedoes for additional targets. Eventually he became the Tonnage King, sinking forty-seven ships before he was captured.

The important aspect of convoy attacks is that many were conducted when remaining on the surface. While less daring commanders preferred to shoot from a safe distance outside the convoy, it is the audacious surface attack inside the convoy which allowed Prien, Kretschmer and Schepke to build up such large scores in a short period of time. Operating on the surface afforded the commanders greater speed, manoeuvrability and visibility and, as previously mentioned, meant that the U-boat was virtually undetectable to the Royal Navy’s Asdic. Other factors such as improved communications, the central organization of assets on shore by BdU, the high standard of commander training, the dearth of appropriate countermeasures and the lack of resources on the Allied side all added up to allow devastating successes to be possible in the early phase of the war.

Loss of the Three Aces

The summer of 1940 heralded the first of two so-called ‘Happy Times’ in which the U-bootwaffe scored notable successes. One reason for the success was due to the capture of French bases; commanders no longer faced a time-consuming journey through the North Sea and could now transit quickly to and from the Atlantic sea lanes from bases along the western coast of France. The other significant factor was the improvements made to faulty torpedoes, which had greatly hindered commanders since the beginning of the war. During this first ‘Happy Time’, highly-skilled aces were attacking convoys from French bases before the technology, tactics, experience and numbers on the Allied side could have an effect. This continued into the autumn of 1940, with Günther Prien and U-47 playing a pivotal role in the highly successful wolfpack attacks which mauled convoys at this time. Although comparatively large successes were accomplished, the Germans simply did not have the numbers of U-boats to truly capitalize on this.

In the winter months, the Atlantic weather and essential periods of refit saved the convoys from further heavy losses. In late February and early March the three leading aces – Prien, Kretschmer and Schepke – were all back in action. Initially convoys lost more ships to these three marauding wolves but these successes were to come to a juddering halt. As we shall discover in due course, March 1941 would be one of the worst months in the history of the U-bootwaffe. Günther Prien was lost when U-47 was sunk with all hands; Otto Kretschmer would survive the sinking of U-99 but would remain in captivity for the duration of the war; and Joachim Schepke would be killed in the loss of U-100. To lose his leading three highly-decorated aces in quick succession was a devastating blow to Dönitz. The death of Günther Prien was a particular loss to the Admiral. He was also a loss to the German nation, who had taken him to their hearts in the astonishing celebrations which followed in the wake of the sinking of HMS Royal Oak in October 1939.

Other commanders such as Heinrich Lehmann-Willenbrock (U-96), Adalbert Schnee (U-201), Erich Topp (U-552) and Reinhard Suhren (U-564) would continue the fight in their Type VIIC U-boats. In January 1942, just after the entry of America into the war, there began a second ‘Happy Time’. Significant successes were achieved on the east coast of America when the weak defences and delay in instituting a convoy system were exploited by Dönitz. The majority of these successes were achieved by the longer range Type IXs which has the requisite range to operate off the coast of America.

The Build Programmes

U-boat build programme On one side of the coin was how quickly the U-boat fleet could be enlarged. Upon the start of hostilities Germany had fifty-seven operational boats, thirty of which were small coastal Type IIs suitable only for operations in the North Sea. Hitler was essentially a soldier concerned with land campaigns so the Kriegsmarine was nowhere near strong enough to challenge the Royal Navy. A successful tonnage war would not be possible for some time because it would take time before the U-boat fleet would have the required number of boats. An aggressive U-boat building programme was initiated but in the early days Germany could only build a couple of new U-boats per month. In this period the new builds were offset by the losses, meaning that the U-boat fleet was not able to increase for some time. For example, one year into the war the U-bootwaffe had much the same number of boats, which did not rise above 100 until March 1941. By October 1941 the strength exceeded 200 and by May 1942 the fleet exceeded 300. In January 1943 the fleet exceeded 400 but the Allies could offset this by their significant gains in many vital areas. Despite very high losses in 1943, the rate at which new boats were being produced in a variety of shipyards meant that the U-bootwaffe retained over 400 U-boats until August 1944. At the end of January 1945, despite the U-boats having suffered a comprehensive defeat, 438 were still available.

Merchant ship build programme On the other side of the coin was the rate at which merchant vessels could be replaced. In 1939 the British merchant fleet numbered around 3,000 ships of 17.5 million tons. Even before official entry into the war in December 1941, the industrial potential of the United States was essential in replacing shipping which had been sunk by German forces. Geographically remote and immune from attack, the first of 2,711 Liberty ships was launched in September 1941. Due to simple construction, these symbols of US industrial might were built in great numbers in an average of forty-two days. Around 5,500 cargo vessels were built during the war by the USA alone, a figure which exceeds the 5,143 ships sunk by all means.

Escort build programme The number of convoy escorts in the early period of the war was inadequate. Indeed it would take until July 1941 before convoys could be given continuous escort for the first time. The types of warships employed in this role varied, with destroyers, frigates, sloops, trawlers and corvettes all being used. Despite heavy rolling and poor conditions on board, a total of 267 ‘Flower’-class corvettes, built cheaply and in large numbers in smaller British and Canadian yards, were important additions to the Allied fleets. By late 1942 the Allies had 450 escorts available for use in the protection of convoys.

The Tonnage War

Dönitz measured the efficiency of his operations by tonnage sunk per U-boat sunk. The peak came in October 1940, when U-47 and other aces sank 352,407 tons for the loss of only one U-boat; this equates to 5.5 ships sunk per month per U-boat at sea. Although in time the greater number of U-boats would allow the actual tonnage sunk per month to eclipse the October 1940 figure, the efficiency rating would not improve. For example, in March 1942 there was a particularly high total of 627,377 tons sunk but this came at the cost of six U-boats lost. Despite these losses, the fact remained that the majority of convoys were passing through unscathed.

Dönitz’s view was that Britain would be forced to surrender if total sinkings (from U-boat, surface fleet and air attack) reached 750,000 tons per month. Allied estimates were a more conservative figure of around 600,000 tons per month. The total sinkings from all sources did not exceed 750,000 tons in any month but did exceed 600,000 tons in four separate months: April 1941, February 1942, March 1942 and March 1943. There was genuine concern regarding the level of losses in 1942, when the average tonnage sunk every month by U-boats was 522,184 tons. The total sunk per month from U-boats, surface vessels and aircraft was even higher – an alarming average of 649,225 tons per month.¹

During the war, U-boats would account for 55 per cent of all ships sunk by German forces. In terms of tonnage the figures were even higher, with the U-bootwaffe responsible for 68 per cent of all tonnage sunk.

Main Factors

In March 1941 the British Prime Minister Winston Churchill was despondent about the shipping losses and formed a Battle of the Atlantic Committee so that the appropriate resources could be organized to face the challenge. There are too many factors to recount in this brief overview of the battle; only the main factors, divided into several groups, shall be introduced here.

Code breaking For many years the work of code breakers at Bletchley Park in cracking the Enigma codes was shrouded in secrecy. The importance of their work is now well documented and it is known that convoys were re-routed to avoid U-boats. Despite the success, there were often periods when it took days to decipher messages, at which point the information was no longer relevant. What is often overlooked is how successful B-Dienst was in cracking British naval codes. In fact, in the early years of the war the German radio-monitoring service was instrumental in directing U-boats towards convoys and it was not until 1943 that the convoy codes were made safe.

Research Research was very important, with the scientists (called ‘boffins’) making many important contributions. For example, it was demonstrated that the number of ships in a convoy might be doubled with only a very slight increase in perimeter size. This was significant because it allowed twice the number of ships to proceed in a convoy with only a very tiny increase in the likelihood of the convoy being spotted.

Aircraft Although many U-boats would be sunk by aircraft during the war, it would take around two years before aircraft would be effective in the anti-submarine role. Created in 1936, Coastal Command was initially responsible for flying reconnaissance patrols over water and had not been trained in attacking U-boats. When attacks were authorized, aircraft such as the slow twin-engined Anson were employing small 100lb bombs which proved to be completely ineffective. In 1940 Coastal Command was issued with aerial depth charges which were much more suitable for the task of sinking U-boats but it would take time before these could be properly utilized. Although the four-engined Sunderland flying boat was available, the Anson and Whitley were incapable of carrying 450lb depth charges. In 1941 Churchill ordered that a number of bombers such as the Wellington be transferred from Bomber Command to Coastal Command. It took time but eventually the command operated appropriate aircraft, flown by trained crew who were able to employ suitable weapons against U-boats.

Although their bombs may have been relatively ineffectual, the Sunderland flying boats proved useful in protecting convoys from U-boat attack. The presence of the four-engined aircraft would force a U-boat to submerge and thus prevent the commander from shadowing the convoy. With their slow underwater speed and limited endurance, the submerged U-boat would lose even a slow-moving convoy and be unable to transmit its location and heading to base.

In August 1940 Focke-Wulf Fw 200C Condor aircraft began long range patrols from near Bordeaux. These were a persistent threat as they followed a convoy and allowed for U-boats to be directed towards the merchantmen. There needed to be some form of air asset to counter this threat and this came in the spring of 1941 when single Hurricane fighters (known as Hurricats) were catapulted from CAM ships (Catapult Armed Merchantmen). Although the Hurricats did not account for many Condors they did introduce an important deterrent effect. The disposable fighters were a rather desperate measure as the brave pilot had no choice but to ditch in the sea once his fuel was expended. The real answer was to be found later in the year in the form of escort carriers, which were usually built upon a commercial ship hull. Despite being slow, small and poorly armoured, these vessels were cheap enough to be built in sufficient numbers and accompany the convoys. In September 1941 the first Condor was shot down by a fighter launched from an escort carrier.

One persistent problem in the early years was the 800-mile long mid-Atlantic gap, which was an exposed area beyond the range of antisubmarine patrol aircraft. The answer was to be found in the long-range B-24 Liberator. A squadron of RAF Liberators operating from Iceland in late 1942 began to plug this gap and despite their small numbers proved invaluable in protecting convoys from attack. Protection of convoys against wolfpack attack was then improved as the numbers of long-range aircraft increased.

Technology The improvements in the technology employed by both sides was vitally important. One may suggest that the Allies were more successful in designing and implementing technological developments. Some of these improvements were as follows –

•In November 1940 a Whitley aircraft was able to use ASV (aircraft to surface vessel) Mk II radar to locate and damage a U-boat. This version was introduced in a wide range of Coastal Command aircraft and used to good effect to detect U-boats on the surface.

•In 1941 10cm radar (Type 271) was installed on corvettes. This was a vital advancement as escorts could now detect U-boats on the surface.

•In 1942 the radar sets were being used to good effect to sink U-boats.

•In 1942 ‘Huff Duff’ (high-frequency direction finding) was fitted aboard escorts. This allowed escorts to gain accurate fixes on U-boats which were transmitting radio signals beyond the range of radar.

•In 1942 Hedgehog, an ahead-firing 24-round anti-submarine mortar, was introduced on escorts. Attacks made on submerged U-boats with this weapon had a very much higher kill rate than depth-charge attacks.

To counter ASV radar, in August 1942 Germany introduced the Metox radar warning receiver; this was used by U-boat crews to warn of the approach of aircraft and allowed them sufficient time to escape. This permitted a rapid recovery from the German perspective but a dramatic change of fortune was to await the U-bootwaffe in the spring of the following year.

The Defeat

In the early months of 1943, between twenty and thirty U-boats were being added to the fleet each month. By March the U-boats were available in large numbers and were close to gaining the upper hand. Although they sank the highest tonnage of any month of the war, a complete reversal of fortune was to occur. In these spring months of 1943 the Allies were beginning to have the assets required to resist the U-boat peril. And, crucially, they introduced the ASV Mk III radar to aircraft of Coastal Command. The reversal occurred in May 1943 – ‘Black May’ – when forty-two U-boats were sunk. On the Allied side, there had been many improvements: code breaking, tactics, training, experience, weapons, radar, more escorts and more aircraft. Additionally, due to the numbers of escort carriers being built up, there were enough resources available to form hunter-killer groups which did not stay with the convoy but actively tracked down and sank U-boats.

Dönitz was so shocked by this reversal of fortune that he ordered a temporary halt to the Atlantic campaign by recalling his boats to base. To counter the threat of aircraft, heavier anti-aircraft weaponry became mandatory within two-level conning towers that looked vastly different to the small ones which had graced the silhouettes of early boats such as U-47. U-boats were ordered to remain on the surface and fight it out with attacking aircraft, but this proved to be a tactical error and was soon countermanded.

In the technological battle between the two sides, new detection systems and acoustic homing torpedoes were introduced. Despite the high numbers of U-boats which were retained in the final years, the Allies continued to maintain the upper hand. U-boats only lasted for a few patrols, with their inexperienced crews often being sunk on their first patrol. Losses were so heavy that by the summer of 1944 operations in the North Atlantic were very limited. In mid-1944 the schnorchel, an extendable mast which allowed the U-boat’s diesel engines to run while submerged, gave the boats higher submerged speed and permitted batteries to be recharged at periscope depth. This made a huge difference as U-boats once again had a chance of evading aircraft. However, by this point so many experienced crews had been lost and there was no hope of a change of fortune with conventional U-boats. Germany was building the Type XXI Elektroboote, which was designed to operate entirely submerged. This had the potential to revolutionize submarine warfare and could, if built in sufficient numbers, turn the tide back in favour of the Germans. But operational Type XXIs were not available in numbers by the end of the war, with only two boats ever departing on war patrols.

Despite huge odds against survival, the half-trained and demoralized men of the U-bootwaffe kept going to sea. They died in vast numbers: out of 1,155 U-boats sent into battle, 725 were sunk. The U-bootwaffe lost over 28,000 men, an enormously high proportion of the men sent into battle.

Conclusion

Winston Churchill knew that the war depended upon the ability to maintain shipping traffic across the Atlantic and could be lost if the campaign was not adequately supported with a variety of resources. Although Germany failed to cut the Atlantic lifeline, which must represent a defeat, the U-bootwaffe was never fully defeated. The Allies clearly had the upper hand in the final two years but Germany still retained a significant number of operational boats and considerable Allied resources had to be employed against them until the end. There were many factors but overall the Allies built enough ships to replace losses, thus allowing the convoys to keep sailing eastwards with their vital cargo to British shores.

Effects of Unrestricted Submarine Warfare

In a work focussing on a German U-boat which sank thirty-one ships, we cannot ignore what occurred after the deadly torpedoes left their tubes. The brave men of the various merchant navies faced dangers and hardships which often exceeded those faced by the servicemen of Great Britain’s armed forces. As for the men aboard the escorts, many of whom were volunteer reservists with no prior experience of the sea, they also endured dirty, cramped and very dangerous conditions. In the Second World War, from the cruel sea that was the North Atlantic to oceans throughout the globe, the British Merchant Navy suffered over 30,000 casualties. The merchant seamen of other nations also suffered greatly, with Norway losing over 3,700 men and Canada losing 1,600 men.

Initially, when Prize Rules were observed, the U-boat men provided the merchant sailors with supplies but this chivalrous behaviour soon ceased as the campaign progressed inexorably toward unrestricted submarine warfare. This meant that merchant ships, operating with civilian crews who ranged from the youngest to the eldest of working age, were torpedoed or shelled without warning. Men who served below the waterline rarely escaped if their ship was sunk by torpedo. The U-boat would then sail away to find another victim, leaving the shipwrecked survivors clinging to pieces of wood or, if they were lucky, in a lifeboat. Convoys did not stop to pick up crews but rescue sometimes came from escorts. For ships sailing independently, the survivors were on their own. Some of their number may have been injured, perhaps with serious burns or through ingesting oil floating on the surface. The survivors may drift for days, fully exposed to the elements with limited or no supplies. Sometimes they would be rescued, other times they would simply die of exposure, of dehydration, or of their wounds.

The effects of what would, on the German side, be thought of as a ‘successful’ attack was horrific. And yet the young men of the U-bootwaffe who had inflicted such suffering and death were exposed to similar horrors. They could be trapped inside their ‘iron coffin’ as it made a slow descent to the ocean floor, all the time waiting for the cracking of the pressure hull which would precipitate their end. Or they could be stuck on the sea floor, unable to surface, their fate being a slow death from suffocation.

***

From September 1939 to March 1941 – the period when U-47 played her part in the deadly Battle of the Atlantic – the defeat of the U-bootwaffe was far from certain, with some on the Allied side fearing the battle would ultimately turn in favour of the U-boat men. It is this early-war environment, firstly of attacks against singular merchant vessels and then in wolfpacks against convoys, which U-47 and her commander operated.

Part II

Patrol & Refit History

Patrol & Refit History Format

The following patrol and refit history of U-47 details all of the main events in the boat’s illustrious career. Rather than a running narrative, the work is presented like a diary, with dates forming each of the headings. The purpose of this chronological format is so that the reader may quickly and effortlessly find what occurred on a particular date, without having to scan through a descriptive prose. To further achieve this aim, the work is presented in note form and in the present tense. At the end of each patrol, a summary and various statistics are provided. Tables and statistics pertaining to the boat’s victims and a discussion of the various speculations surrounding the loss of U-47 conclude this section.

*References to ‘BdU’ refer either to the BdU (Befehlshaber der Unterseeboote meaning Commander-In-Chief for U-boats) Karl Dönitz himself, or the Operations Department (BdU Op., which was later known as the U-Boat Command). This title was previously FdU (Führer der Unterseeboote meaning Flag Officer for U-boats) and changed to BdU on 17 October 1939.

Map details

Other than the last patrol, in which the normal latitude and longitude system is given, the locations in the patrol history are specified by their German Marinequadratkarte code, which the Kriegsmarine used to define positions on the world’s seas and oceans.

Victim details and codes

After a description of each sinking, the details are recorded in bold print in the following order –

•Vessel name.

•Date of attack.

•Attack time – The time noted in the first nine patrols is that which is recorded in U-47 ’s KTB for the start of the attack. Due to U-47 being sunk during her tenth patrol, the KTB is unavailable for that patrol. Therefore, the time noted during the tenth patrol is the time of the first hit scored against the vessel under attack, as per Allied sources.

•Nationality.

•Vessel type.

•Tonnage – Tonnage for merchant ships is in gross registered tons (grt), which is a measure of volume and shows the total internal volume of a vessel (1 grt is 100 cubic feet). Tonnage for warships is in long tons (lt), which is a measure of weight and shows the actual weight of a vessel.

•Weapons used.

•Attack location – The location noted in the first nine patrols is the Marinequadratkarte grid location recorded in U-47 ’s KTB. The location noted during the tenth patrol is that of the vessel under attack, as per Allied sources.

•Convoy designation.

Summary tables

In the summary tables, the codes indicate the following vessels -

In the Type column, A refers to air-driven G7a torpedoes and E refers to electrically-powered G7e torpedoes.

Other information

Patrol length The patrol length totals are inclusive of the departure and arrival dates. For example, if the boat left on 1 January and arrived on 5 January, this would amount to a patrol length of five days.

Estimated tonnages In the post-patrol analysis, the ‘estimated ships sunk’ is Prien’s estimate, as given in the boat’s KTBs. This differed sometimes from the tonnage credited to U-47 by BdU.

Convoy designations HX convoys sailed from Halifax, Nova Scotia, and contained ships which could sail at 8 or 9 knots. SC convoys sailed from Sydney, Cape Breton Island, Nova Scotia but they were slower, with ships only able to maintain 6 or 7 knots and took around sixteen days to make the dangerous passage to Britain.

Refit and modification designations

The periods in dock and the modifications made during these periods have been assigned a code by the author. Each period of refit/modification has been assigned a letter. Each modification known to have taken place in this period has also been given a number. For example, A2 is the second modification known to be made in period A. The periods are as follows –

When the refit period is not known, the modifications have been assigned the code X.

Pre-War & Training

21 Nov 36 The Kriegsmarine orders a Type VIIB U-boat from the Friedrich Krupp Germaniawerft A.G. shipyards in Kiel (hereafter referred to as Germaniawerft). Part of the U-45 to U-55 batch, the boat has construction number 583 and field post number 18837.

25 Feb 37 The keel is laid down.¹

Note: Some sources suggest 01 Apr 37 for the keel being laid down.²

01 Oct 38 The U-boat’s future commander, Oberleutnant zur See Günther Prien, begins his Baubelehrung period in which he learns technical information from the shipyard personnel about the construction of U-47. This scheme is supervised by the Kriegsshiffbaulehrabteilung (warship construction training detachment).

29 Oct 38 U-47 is launched from Slip 3.

18 Nov 38 First Watch Officer Leutnant zur See Engelbert Endrass begins his Baubelehrung period. In the next few weeks more and more crew will join the boat.

06 Dec 38 The boat is delivered to the Kriegsmarine, leaving the Germaniawerft shed but remaining in the naval base in Kiel.

17 Dec 38 The pristine U-47 is commissioned into the Kriegsmarine in Kiel during a ceremony known as the Indienststellung. During the commissioning ceremony, Prien adds the white commissioning pennant to the commander’s flagstaff. The boat is assigned to the U-Flottille Wegener.

Pre-war features

The following pre-war features were present upon U-47 before the commencement of hostilities –

•‘47’ painted in large white numerals one metre tall on both sides of the conning tower.

•A small oval plate (on each side) inscribed with ‘U 47’ just under the small drainage holes near to the bow.

•A bronze eagle plaque on the front face of the tower.

•The red horseshoe-shaped lifebelts on each side of the conning tower had ‘U-Flottille Wegener’, ‘U’ and ‘47’ marked in white letters.

•Two red and white emergency rescue buoys. One was located on the aft deck (just forward of the 20mm gun mount) and the other was on the forward deck (just aft of the capstan). These red and white buoys had three white strips which curved in a circular pattern around the outside. Black text appeared upon these strips; the topmost strip read ‘Unterseeboot’ followed by ‘U 47’ below.

•A dark grey patch of paint around, and to the rear of, the diesel exhaust outlet. This helped to camouflage the staining from the dirty exhaust gases.

During the pre-war period, the U-bootwaffe experimented with several paint colours on the upper hull and conning towers. In addition to Dunkelgrau 51 – the most common of the Kriegsmarine paints – darker shades of grey were also used. Some of the pre-war shots of U-47 show a dark upper hull and conning tower so it may be the case that U-47 was painted for some pre-war periods in the dark grey Dunkelgrau 52 (RAL7024).

Refit A

Work completed At some point in the early months of 1939, the net cutter is removed from the bow (A1).

Pre-war activities

Early 1939 Daily trial runs are made, first in the bay and then in the Baltic Sea.

March 1939 U-47 participates in exercises, during which particularly bad weather is experienced.

May 1939 U-47 departs from Wilhelmshaven to participate in war games in the North Atlantic and Bay of Biscay. These large-scale exercises, under the command of Prien’s former commander on U-26, Werner Hartmann, include practice in attacking convoys, prototype wolfpack operations, communication and minelaying. The Kriegsmarine ships assigned to the annual fleet cruise to Lisbon and the western area of the Mediterranean compose the convoy to be attacked. These consist of the tanker Altmark, a freighter, and the tenders Erwin Wassner and Saar, with the latter two vessels doubling as both convoy ships and defending escorts. The fifteen U-boats deploy in five packs of three along a patrol line several hundreds of miles long and attack the targets between 12 and 14 May.³ Prien is the most aggressive and achieves the best results during these war games. At some point U-47 visits Lisbon and also Ceuta in Spanish Morocco.

June 1939 U-47 returns to Wilhelmshaven.

July 1939 Torpedo exercises are conducted in the Baltic Sea.

Refit B

Period in refit July or August 1939 in Germaniawerft, Kiel.

Work completed The following modifications were made at some point during, or prior to, August 1939 –

•Additional strips added on the deck around the 88mm deck gun (B1).

•A small spray deflector added midway up the front of the conning tower (B2).

•A breakwater (splash guard) added on each side of the hull casing, outboard of the 88mm deck gun (B3).

•The two red and white emergency rescue buoys moved inside deck hatches so as to be less obstructive to the crews working on the deck (B4).

•The dark grey/black patches over the diesel exhaust outlets painted over with the upper colour, Dunkelgrau 51 (B5).

•The net cutter reintroduced to the bow (B6).

It is likely that the above modifications were made within a few weeks prior to departure in mid-August 1939.

Patrol 1: The Opening Shots

Pre-patrol

15 Aug 39 It all begins with a telephone call. At 1200, on behalf of the head of the Kriegsmarine, Erich Raeder, Lieutenant Fraesdorf telephones FdU Karl Dönitz to state that ‘the officers’ party for U-boat officers’¹ is to be held on Saturday, 19 August and as many as possible are to be present. This is not an invitation to a social gathering. Rather it is a coded message meaning that U-boats are to be deployed on war operations. In effect the message is the preface for what is to become the Second World War.

All boats and commanders are ordered to report to the tender Hecht where they will be briefed on the ‘emergency exercise North Sea’.² U-47 is hurriedly recalled from Neustadt to Kiel, where Prien reports aboard the Hecht. Preparations begin for departure on 19 August.

17 Aug 39 Preparations continue apace. There is a concern that there will be a shortage of torpedoes.

18 Aug 39 The practice torpedo-firing sessions end. All officers are fully briefed.

Patrol

19 Aug 39 At 0000, U-47 departs Kiel along with U-45, U-46, U-48 and U-52. Five Type IXs and four Type VIIs depart from Wilhelmshaven at the same time. These fourteen boats constitute the first wave of U-boats taking up waiting positions in the Atlantic. They will all be concentrating upon finding merchant ships, which are expected to be sailing alone rather than in convoy.

In the afternoon, while the boat is underway, all pre-war identification markings are removed. These features are as follows –

•Large white 47 painted over with Dunkelgrau 51 paint (C1).

•Oval bow plates removed (C2).

•Bronze eagle plaque removed from front of tower (C3).

•White ‘U-Flottille Wegener’, ‘U’ and ‘47’ inscriptions on the two red horseshoe-shaped lifebelts painted over (C4).

22 Aug 39 The U-boat sails around the north of the Shetlands.

24 Aug 39 At 1553 FdU radios that England (i.e. the United Kingdom) and Poland are mobilizing, and that a non-aggression pact with the Soviet Union has been signed. The planned invasion of Poland, which was due to take place on 26 August, is postponed until 1 September. The pact allows Dönitz to move U-boats from the Baltic Sea into the North Sea. Other boats can be moved farther west.

28 Aug 39 FdU updates the U-boats in the Atlantic on the political situation via a detailed radio report. Merchant ships have been ordered to darken their lights and advised to steer clear of normal shipping routes.

29 Aug 39 U-47 reaches her assigned waiting area in BF 48 in the Bay of Biscay. The 88mm deck gun is cleaned.

30 Aug 39 U-47 remains in her assigned waiting area.

31 Aug 39 At 1830 FdU radios all Atlantic boats with the message they have been waiting for. Hostilities with Poland will commence the next morning.

01 Sep 39 At 0445, Germany commences hostilities against Poland.

02 Sep 39 Two French submarines are sighted in the morning. As the attitude of French and British governments is uncertain, no attacks are to be made against these French submarines except in self-defence.

The 20mm Flak gun is cleaned and ammunition made ready. Today will be the final day of waiting in their assigned area.

03 Sep 39 Great Britain declares war on Germany at 1115. The radio message at 1256 from the Naval War Staff states: ‘Hostilities with England with immediate effect’.³

At 1400, FdU radios: ‘U-boats to make war on merchant shipping in accordance with operations order’.⁴ This additional radio signal is to remind U-boat skippers of the operational order specifying that attacks against merchant shipping are to be conducted in accordance with the Prize Rules. These mean that ships cannot be sunk without warning. They must be stopped and searched; only if found to be an enemy ship, or a neutral with contraband bound for an Allied port, can they be sunk. However, they can only be sunk after the safety of the crew is assured. Troopships and vessels in convoy are excluded from these rules.

Later, at 1550, another order is radioed: ‘Open hostilities against England immediately, do not wait to be attacked first.’⁵

Even though a state of war exists between Germany and France from 1700, the situation between the countries is still unclear. As a result, incidents with French shipping are to be avoided at all costs. Prien expresses clear displeasure at this point when he writes that the French declaration of war is a ‘disgusting manacle’⁶ in view of the nearby French submarines. ‘Do they have such an order?’ he asks.⁷

The Commonwealth nations rally behind Britain, with Australia, New Zealand and India declaring war on Germany. South Africa and Canada will also soon declare war (on 6 and 10 September respectively).

04 Sep 39 After the sinking of the Athenia by U-30, an attack which was made against orders, a furious FdU radios another reminder at 1655 that the 1930 Submarine Protocol (Prize Rules) is to be strictly adhered to. A further order from Hitler is issued at 2353 to the effect that no hostile action is to be taken against passenger ships, even in convoy. These orders, which will be gradually relaxed over the passing months, tie the hands of U-boat commanders. They inhibit their operational effectiveness and prevent the U-bootwaffe’s first wave from making a more dramatic impact.

04 Sep 39 At this very early stage of the war, the convoy system has yet to be established so the only vessels that U-47 will encounter will be single ships in the merchant lanes. The first ship encountered by Prien is the Maliankos, an old and dirty Greek freighter of 3,884 grt carrying resin minerals to Rotterdam. Having examined its papers, the vessel is allowed to continue.

In the afternoon, two steamers – one Swedish and the other Norwegian – are sighted heading west.

05 Sep 39 At 0732, with clear visibility, the zig-zagging British merchantman Bosnia is sighted. Carrying 3,200 tons of sulphur from Sicily to Galveston, she is a short and dumpy freighter with a flaming red stack, a black superstructure and a grass-green bottom. In accordance with Prize Rules, U-47 orders the Bosnia to heave-to. When the ship turns away, the U-boat crew fires a warning shot from the deck gun to stop the vessel. Instead of stopping, the Bosnia sends the U-boat alarm signal ‘SSS’ and tries to escape. Two further warning shots are fired. Prien then orders four rounds fired from the deck gun, three of which hit the vessel. The panicking crew abandon their ship, capsizing a lifeboat in the process. The crew of U-47 assist the survivors by bailing out their capsized lifeboat and hauling two sailors, Woods and Bird, aboard U-47. For a moment the survivors think that the German submariners are assaulting Woods, when in fact the U-boat men are undertaking artificial respiration. The efforts are in vain as Woods later dies.

Prien then allows the stricken crew to be picked up by the Eidanger, a neutral Norwegian tanker which has arrived at the scene. With the thirty-six survivors aboard the Eidanger bound for Lisbon, the Bosnia is sent to the bottom of the Atlantic with a torpedo.

Sunk: Bosnia, 05 Sep 39, 0815, British, steam freighter, 2,407 grt, torpedo & gunfire, BF 7225

At 1215 an aircraft forces the crew to dive. The screws of a French Bourrasque-class destroyer are then heard. Then three French destroyers set a course for U-47, passing over the submerged U-boat. Much to the surprise and relief of the crew sitting at a depth of 120 metres, no depth charges are dropped. At this time U-boats are not to engage with any French vessels, which are to be avoided ‘at all costs’.⁸

06 Sep 39 Visibility is good once again. The Rio Claro, a British freighter carrying coal from Sunderland to Montevideo, is sighted at 1300. When U-47 surfaces, the ship stops. Despite a warning shot from the deck gun at 1418, the wireless operator aboard the Rio Claro sends the U-boat alarm signal ‘SSS’. Three rounds are fired from the deck gun into the bridge to silence the radio, whereupon the crew wisely take to the lifeboats. The Rio Claro is then