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Duration 45:05

The battle that frightened Churchill: the war in the Atlantic

On 3 September 1939, the passenger liner Athenia was sunk by U30. So began the Battle of the Atlantic, the longest and most complex campaign of the Second World War. The battle pitted the submariners of the Kriegsmarine against the Allied merchant fleet who were providing Britain’s vital life line. This talk follows the changes in fortune of both the Kriegsmarine and the merchant fleet, and explains why Winston Churchill knew that the Battle of the Atlantic was the battle that Britain could not afford to lose.

Further Information

The Battle Commences:

3rd September 1939

11:00 Britain declares war on Germany

12:59 Berlin sends encoded message to all Kriegsmarine “Hostilities with England effective immediately”

14:00 Karl Doenitz sends message to Kriegsmarine warning them of Prize restrictions

16:30 Cruise liner Athenia spotted by U-30

19:40 Two torpedoes fired at the Athenia the first hitting her and the second going wide

At this point the Battle of the Atlantic begins and will rage for the next 69 months – the longest Campaign of WW2

Document gallery


Ladies and Gentlemen, thank you for coming and welcome to The National Archives.

Today’s talk is in two parts. Firstly I’m going to try and explain how the advantage in the Atlantic swung back and forth between the Allies and Germany in the period 1939 to 1943. Next I’ll take you through some of the reasons why the Allies gained the upper hand and eventually won the Battle of the Atlantic.

The talk you are about to hear grew out of work I’m doing on the World War Two convoy card index and improving access to the records of convoys in ADM199, ADM217 and ADM237.

The aim of this work is to remove the card index and make much improved information available on World War Two convoys on our online catalogue.

Reading these records has given me a real insight into just how hard fought the battle of the Atlantic was and just how much was at stake should we have failed to get the convoys through. In fact, so high were the stakes that Churchill admitted in his Second World War history ‘Their Finest Hour’ that the U-boat threat to the shipping lanes of the Atlantic was the only thing that frightened him during World War Two.

The battle itself was fought between Merchant Navy convoys and their escorts fighting to keep Britain provisioned and the U-boats sent to starve Britain out of the war.

The battle of the Atlantic pitted largely civilian crews and naval reserves against the German Navy, or Kriegsmarine, in the longest, largest and most complex battle of World War Two.

A good place to start is always the beginning so let’s journey back exactly 70 years to the 3rd of September 1939. At 11:15 families the length and breadth of Britain sat around  wireless sets to hear Neville Chaimberlain tell the nation the news they had both dreaded and expected. Britain and France had declared war on Germany.

At 12:59 an encoded message was sent to the Kriegsmarine to inform them that hostilities with England were effective immediately. The message deliberately did not mention hostilities with France.

At 14:00 hours Vice-Admiral Karl Doenitz informed the Kriegsmarine the ‘Prize’ restrictions were to be adhered to. That meant that unarmed merchant ships had to be boarded and searched and only sunk if carrying cargo that was to be used for the war effort and after their crews had been put into lifeboats. Passenger ships were not to be boarded or sunk at all. Both of these messages were received and logged by U-boat U-30.

At 4:30, U-30 spots the Athenia on a course away from Britain and observed that she seemed to be blacked out and taking an evasive zigzagging course. Her commander, Fritz-Julius Lemp, decided she was an armed merchant cruiser and fair game within the ‘Prize Rules’. At 7:40 Lemp gave the order to fire two torpedoes at the Athenia. The first tears through the ship between the engine room and the boiler room while the second one goes wide. A few minutes later the radio operator onboard U-30 picks up a distress call of a passenger liner.

Lemp panics, checks his Lloyds Register and realises he’s made a terrible mistake. The fog of war had descended early over Lemp and the battle of the Atlantic begins almost by accident due to a terrible error of judgement.

From this terrible beginning the battle raged for another 69 months from the day war was declared until VE day in May 1945.

The Athenia set out from Glasgow on the 1st of September with 1,418 passengers and crew. 112 people died including 28 of the 300 Americans on board. Some died as a result of the rescue ship, the Knute Nelson, crushing a lifeboat full of survivors with its propellers.

It’s ironic that those killed were victims of a war that had not even started in Britain when they boarded the ship.

The question that arises here, with the loss of so many American passengers, was why America was not drawn into the war at that point as she had been after the sinking of the Lusitania in 1915. The answer was simple. With the knowledge that Hitler was desperate to keep America out of the war, Lent failed to report the sinking until he returned to base two weeks later.

In the meantime Germany denied any involvement and accused the British of a dirty tricks campaign, even going so far as to blame Churchill for sinking one of his own ships to make it seem that Germany had embarked on a campaign of unrestricted submarine warfare.

On finding out that Lemp had sunk the Athenia, Doenitz, under orders from Berlin, swore the crew to secrecy and falsified the U-30’s logs. The truth about the Athenia did not emerge until Doenitz confessed to Lent’s error and the alteration of the logs at the Nuremburg Trials in 1945-46.

So that is how the battle of the Atlantic started but why did it need to be waged in the first place? The answer comes down to the simple fact that Britain as an island nation, now cut off from mainland Europe, supplies had to come from greater distance and it was almost every commodity that needed to be imported.

Britain relied heavily on her Commonwealth and none more so than Canada. This meant that almost everything Britain needed was to come across the dangerous shipping lanes of the Atlantic. Food, fuel, munitions and later troops to prepare for the recapture of France.

Merchant ships were to become the lifeline that kept Britain fed, fuelled and fighting and both Hitler and Doenitz knew this. The obvious way to get Britain out of the war was to starve her out. Merchant vessels and their crews were now front line targets.

The evacuation of Dunkirk and the retreat of the British Expeditionary Forces was officially known as Operation Dynamo. Although not part of the battle of the Atlantic it was to have a profound impact on it.

With the B.E.F. in retreat and the French Army in disarray the fall of France was inevitable. Once Germany controlled France they also controlled the Breton ports of Brest, Lorient and Saint-Nazaire amongst others. These were all to become major submarine bases.

Operating from these bases cut seven days off the U-boat hazardous journey through Scapa Flow into the North Sea, around Scotland and out into the Atlantic. Now the U-boats were able to go directly out to sea saving time and fuel and in far less risk. As a direct consequence more Royal Navy ships were called upon to defend the south of England from attack from the Channel and northern France. So, just when the convoys needed greater protection from the U-boat threat they found their escorts greatly reduced.

As soon as word reached Doenitz that France had surrendered, he expressed his joy that they now held the French ports and immediately organised a car to take him and his intelligence officer to the Atlantic coast.

Doenitz was particularly pleased with the facilities at Lorient. He requisitioned a chateau overlooking the peninsula called Kernevel from where all U-boat activity in the Atlantic was to be controlled.

He also immediately ordered built seven huge submarine pens on the Keroman peninsula which he could overlook from the terrace at Kernevel. These can still be seen in Lorient today.

The first U-boat to take up operational duties from the new base at Lorient was U-30. The lack of Royal Navy escorts and ease with which the U-boat fleet could now operate from Brittany and the Bay of Biscay turned the war in the Atlantic in Germany’s favour.

In September 1940 fast convoy HX 72 was attacked and 11 of the 41 ships taking part in the convoy were sunk. The commodore of the convoy faced sceptics when he insisted that at least two U-boats had worked together to sink the convoy.

But, if there was any doubt in the mind of the Admiralty that submarines were now hunting in packs, this was dispelled by what happened to convoy SC7 in October of 1940.

U-38, U-46, U-48, U-49, U-100, U-101 and U-123 attacked convoy SC 7 between the 16th and 19th of October, sinking 20 of the 37 ships in convoy and damaging a further six. Part of the pack plus U-47 then turned their attention to convoy HX 79 sinking a further 12 ships. The two attacks put a total of over 175,000 tons of shipping out of action.

A total of 63 ships were lost in October 1940, totalling some 442,985 tons. 28 of those ships were lost on the 18th and 19th of October. These proved to be the worst two days for shipping losses of the entire war.

The whole attack had been carefully coordinated by Doenitz from Kernevel. The wolf pack was now a deadly reality and for the submariners of the Kriegsmarine, operating unhindered from their French ports, their ‘Happy Time’ had begun.

As we’ve seen from the fall of France in June 1940, the battle of the Atlantic swung in favour of the U-boats. During their ‘Happy Time’ it was more dangerous to be a merchant seaman than in part of any of the armed services, so great were their losses. Even merchant seaman who survived initial attacks still faced the danger of the icy waters of the North Atlantic and chances of rescue were slim. Ships could not stop to pick up survivors while U-boats were still in the area.

From June 1940, shipping losses rose dramatically, falling back only slightly across the winter months when it was difficult for U-boats to carry out attacks during winter storms. However, for reasons we’re about to look at, things started to turn the following spring and losses fell back to pre-June 1940 levels by the summer of 1941.

In the winter of 1940, Winston Churchill wrote in his diary ‘The mortal danger to our lifelines gnawed at my bowels’. By early 1941 Churchill insisted that resources should be poured into the newly named ‘Battle of the Atlantic’. One of the most important tactical changes was that permanent escort groups were formed and the Merchant Navy no longer had to rely on whatever ships the Royal Navy could supply.

This was partly possible because of an increase in the size of The Royal Canadian Navy, who were mass producing cheap corvettes, and the loan of 50 old United States warships.

A training establishment was set up in the Hebrides to train escort crews and Western Approaches Command was moved from Plymouth to Derby House in Liverpool, to enable better control and greater communication with the convoys.

In addition the Admiralty took over the operations of Coastal Command aircraft, ensuring much better cooperation between aircraft and escorts.

From early 1941 shortwave radar sets began to be fitted to ships and aircraft and the benefits of all these changes soon began to be felt.

On the 7th of March 1941, U-47, commanded by Gunther Prien, U-boat ace of 30 Allied sinkings, including the Royal Oak and the Arandora Star, was lost while attacking convoy OB 293. All 45 of his crew were lost.

Convoy HX 112 left Halifax, Nova Scotia, on the 1st of March 1941 and was escorted by the fifth escort group including the destroyers HMS Walker and HMS Vanoc. The convoy was attacked on the 15th of March by a wolf pack consisting of U-10, U-100, U-99, U-74 and U-37.

U-100 torpedoed a tanker which caught fire but did not sink, however the escorts managed to frustrate all other attacks that night. The pack attacked again the following night and this time managed to sink five ships in less that an hour. However U-100 then attained the dubious honour of becoming the first U-boat in World War Two to be detected by radar, mounted aboard HMS Vanoc.

The escort soon caught up with her and HMS Walker depth-charged the U-boat forcing her to surface. This allowed HMS Vanoc the opportunity to ram her. 47 of her crew of 53 went down with the ship including their captain Joachim Shepke, a U-boat ace responsible for 37 losses.

While trying to make an escape U-99 was picked up on ASDIC on board Walker. She was depth-charged and forced to the surface where her crew were taken prisoner, including the captain Otto Kretschmer another U-boat ace whose 43 sinkings were not to be surpassed by any other U-boat commander.

In just 10 days Germany had lost three U-boat aces that between them were responsible for sending nearly 625,000 tons of shipping to the bottom of the Atlantic.

The convoy arrived in Liverpool on the 20th of March and news had already reached there that there were U-boat prisoners of war onboard Walker. Liverpool had fared particularly badly with shipping losses and losses of loved ones. There were ugly scenes on the docks and the crowd had to be held at bay by soldiers with bayonets drawn. The prisoners of war were later moved to Canada where they spent the rest of the war.

The German High Command realised that the loss of three high profile aces in just over a week would have a serious effect on morale and decided not to inform the public that Prien was missing, Shepke was dead and Kretschmer was a prisoner of war. However, the Allies who knew that Prien was lost from information gathered from the prisoners taken from U-99, seized the propaganda opportunity and dropped thousands of leaflets over Germany asking ‘Wo ist Prien?’

The lack of official information led to all sorts of rumours, including one that said Prien had turned anti-Nazi and had been sent to the camp at Dachau. It wasn’t until 23rd of May 1941 that it was finally announced to the German public that Prien was dead.

For the German public this news was made worse by the fact that since the day Prien had gone missing a further six U-boats had been sunk in the Atlantic, including U-110.

On the 9th of May 1941 U-110, commanded by Fritz-Julius Lemp of Athenia notoriety, joined U-201 commanded by Adalbert Schnee in an attack on convoy OB 318. U-110 managed to sink the Bengore Head before she realised she was being hunted by ASDIC.

The U-boat dived [but] was depth-charged and damaged. Lemp gave the order to surface and the crew abandoned ship whilst under fire from HMS Bulldog. Lemp ordered the ballast tanks to be flooded to ensure the ship went down before abandoning ship himself.

At some point whilst in the water Lemp must have realised that the U-110 was not sinking and made an attempt to return to the U-boat. It was the last time he was ever seen. The other survivors were picked up by HMS Aubretia.

HMS Bulldog and HMS Broadway were just about to finish U-110 off when Bulldog’s captain Joe Baker-Cresswell decided instead to board her. He sent sub-Lieutenant David Balme aboard to salvage what he could from the sinking sub under the codename operation Primrose. What they found was a complete set of cipher books and an Enigma machine. This was a complete intelligence goldmine and the material was moved quickly and undercover.

The submarine was put under tow. However on the morning of the 10th it was thought necessary to let U-110 sink and let Germany think that the cipher books and Enigma machine were at the bottom of the Atlantic. The ruse worked and it was many months before suspicions were raised and a fourth rota added to the Enigma machine. Indeed enough months to ensure the Allies had the upper hand.

The Enigma messages that were decoded at Bletchley Park tracked the U-boats movements in the Atlantic and ensured that hundreds of thousands of shipping tons made it through safely. The ‘Happy Time’ was over for now.

While America was being arguably drawn into the war by the U-boat threat in the Atlantic, it was an event in another ocean that eventually made America a combatant.

On the 7th of December 1941 Japan attacked the American fleet at Pearl Harbour. Germany, being part of the tri-partite pact with Japan and Italy, declared war on the United States on the 11th of December 1941.

Doenitz relished this news. Although Hitler had wanted America kept out of the war the Kriegsmarine had witnessed her ships flying the stars and stripes carrying war supplies to Britain for months, and for him the charade of American neutrality was now over.

He had briefed Hitler months before about U-boat patrols off America’s eastern seaboard and said the action should be like a roll of drums off the American coast, or Paukenschlag.

Doenitz originally wanted 12 type-9 submarines for Operation Drumbeat but he was granted just six, one of which was not fit for the operation. The type-9 were the only submarines with the capacity to make the 3,000 mile journey from Brittany to New York without refuelling.

U-123, commanded by Reinhard Hardegan, was one of the first U-boats to leave for America on the 23rd of December. She was prepared for the voyage from the newly finished Keroman 1 pen at Lorient.

By the 12th of January 1942 the Admiralty were in no doubt that a large U-boat force was making its way to the North American seaboard and a warning to this effect was sent to Admiral Ernest J King, commander in chief of the US Navy. However King did not like the convoy system and believed that lone ships had a better chance against the U-boat threat.

No serious action was taken to prepare for the inevitable attacks and shipping remained unprotected and port and harbour security was haphazard. No lessons at all were taken from the British experience of the first ‘Happy Time’.

Hardegan reached New York Bay in January 1942 to find a city brightly lit, shipping using navigation lights and lightships lighting the harbours. He managed to get so close to shore he records in his log ‘Seeing a ferris wheel and a roundabout working on Coney Island’.

It was an easy task to pick off ships that were backlit from the lights of the harbour. Ships operating alone and without escorts were also easy pickings.

By the end of January the Drumbeat ships had sunk 23 ships, equalling 156,939 tons of shipping, without any loss to themselves. Worse news however was to come. In February, the flow of information from Enigma decripts had dried up and it was now impossible to know where U-boats were operating.

The German High Command, in particular Doenitz, had become suspicious of coincidences on the shipping routes and a fourth rota was added to Enigma. The second ‘Happy Time’ had begun for the Kriegsmarine.

Doenitz deployed second and third waves of submarines to the United States. Such were the rich pickings in those waters, the smaller type-7 boats were sent with their drinking water tanks full of diesel fuel and torpedoes and supplies crammed into crew quarters.

Yet Admiral King still did not think to protect the shipping off the eastern seaboard, having become completely preoccupied with operations against the Japanese in the Pacific.

The American public, alarmed at the losses, were reassured by misleading propaganda that many U-boats had been sunk in return for these losses. In fact the first sinking of a U-boat took place three months after Operation Drumbeat had begun. U-85 was sunk on the 14th of April 1942 by USS Roper.

The US government instigated the ‘Loose lips sink ships’ propaganda campaign in 1942. It was not only designed to deny Germany information on ships movements but also to stem the flow of communication to the American public on just how much shipping was being lost.

In March 1942 Hardegan returned to the eastern American seaboard in U-123. He noted that although some measures had been taken security was still lax. He spotted an oil tanker battling from Jacksonville Beach, Florida and after torpedoing the tanker, The Gulf America, Hardegan slipped between the beach and the stricken ship to avoid firing shells onto the shore. He was then able to finish off the tanker by firing bullets and shells while a shocked crowd looked on from the beach.

With very little intelligence being interpreted by Bletchley Park the Germans were able to deploy the first of the new type-14 submarine off the eastern seaboard in April 1942.

U-459 was the first of the vessels, known as ‘milk cows’, to be deployed. These were sub-surface supply vessels which carried enough fuel, food, water and torpedoes to enable 12 type-7 U-boats to operate effectively off the eastern seaboard. They also had an onboard bakery so they could supply fresh bread daily to the U-boat crews.

With more U-boats able to operate off the eastern seaboard Doenitz shifted the focus of attacks to a far wider area. U-boats were operating up and down the coast all the way from the Caribbean to Nova Scotia, stretching what little defences there were to breaking point.

Let me put this into perspective for you. During the first six months of 1942, one in five of all ships sunk were sunk off the eastern American seaboard, while four of the 21 U-boats lost were in the same waters. A comment in ADM223/15 dated the 30th of March 1942 states that the only serious restraint to U-boat operations there, i.e. off the eastern seaboard, is imposed by the torpedo capacity of the U-boats.

Churchill was becoming increasingly frustrated by the fact convoys were being escorted safely over the Atlantic only to be sunk in American harbours and coastal waters.

By 1941 the U-boat threat was being brought under some control by improvements made to anti-submarine warfare. The lack of action by Admiral King meant that seven million tons of shipping was lost or damaged in 1942. With such enormous losses of cargo Britain was getting desperately close to collapse and a shortfall of two million tons of oil was being forecast by the winter of 1942. In April of that year Churchill called on Roosevelt to take drastic action.

In 1942 there was also a hidden danger to the convoys. Unbeknown to the Admiralty, the German naval intelligence service, B-Dienst, had broken the Admiralty’s naval cipher-three, used for communication with convoys and escorts. So at the same time U-boats were enjoying success off America’s eastern seaboard, Doenitz was able to read about 80% of the traffic sent by the cipher. By the summer of 1942 Doenitz believed it was time for a return to all out warfare on the convoys in the North Atlantic.

A U.S. Navy manual describes the effect of Drumbeat and the subsequent attacks thus: ‘The massacre enjoyed by the U-boats along our Atlantic coast in 1942 was as much a national disaster as if saboteurs had destroyed half a dozen of our biggest war plants’.

The very public sinking of the Gulf America by U-123 shocked the nation as a whole and at last restrictions were put in place about lighting around harbours and ports.

By late spring of 1942 Admiral Andrews, responsible for the North Atlantic coastal frontier, took the decision to operate a limited convoy system with ships only sailing during daylight hours. A programme of 60 ships in 60 days was promised by Roosevelt to meet the shortfall in vessels able to engage the U-boats.

In addition a number of corvettes were transferred from UK waters to the eastern seaboard. 53 squadron RAF Coastal Command was also deployed on Rhode Island to protect shipping in New York harbour. Trained escort crew on Royal Navy ships took over escort duties on tanker convoys and in the Caribbean.

The situation at last started to improve. However this did become very close to being too little too late as the total ship losses for 1942 peaked in June with 173 ships lost, 144 of them to U-boats.

Mid-1942 also saw the introduction of a new submarine killing weapon, the Hedgehog, which we’ll look at a bit later.

In the summer of 1942 Doenitz, confronted by a number of puzzling losses to his U-boat fleet, was forced to consider that the RAF were fitting radar to planes as well as ships and that somehow the Allies were picking up radio traffic from the wolf packs. By late July 1942 he announced to the German people that the months ahead would not be as fruitful as those just passed.

He moved the main operations of his U-boats into the ‘Black Pit’, a notorious area of the mid-North Atlantic not covered by air support.

In the autumn of 1942 the war took a particularly nasty turn. On the 12th of September U-156, commanded by Werner Hartenstein, torpedoed and sank the RMS Laconia, who was carrying over 2,700 passengers and prisoners of war as well as her crew. The Laconia was used as a troop carrier and Hartenstein had assumed that this is what he had hit. However after hearing cries for help in Italian he picked up several survivors from the water and after learning actually who was on the liner he launched a rescue.

He took four lifeboats in tow and crammed the U-boat with survivors. Incredibly Doenitz supported this action and despatched a further two German U-boats and an Italian U-boat to help with the rescue until Vichy French ships could get to the area. Medical assistance was given to those who needed it and the kitchen struggled to make enough soup to feed everybody. Crews gave up bunks onboard the U-boats to women and children.

The U-boats draped red crosses across their hull and Hartenstein broadcasted radio messages in English asking for help and guaranteeing the safety of ships that came to the rescue. These messages were disregarded as a German trick

On the 16th of September, pilot James Harden flew his American B-24 Liberator over the scene. Astonished, he radioed in for advice and incredibly Captain Robert Richardson at HQ ordered him to attack the U-boats. As he flew over the second time the survivors cheered, thinking he was dropping much needed supplies. What he actually dropped were depth charges, which inflicted damage to U-156.

Unsurprisingly Doenitz was furious and issued the so called ‘Laconia order’ which stated that all attempts to help crews should cease forthwith.

At Nurenburg prosecutors tried to say that the Laconia order was a licence to shoot survivors in lifeboats. It clearly was not and the prosecution dropped the argument, however no punishment was ever given to Richardson.

On the 16th of March 1943 convoys HX 229 and SC 122 were attacked. Despite the convoys being well protected by warships and air cover 22 ships were lost. However these proved to be just a fraction of the 120 ships lost that month. Berlin rejoiced while London contemplated defeat and even considered scrapping the whole convoy system.

However, these early losses in 1943 proved to be the last throw of the dice for the U-boats. In early April convoy HX 231 lost only six ships despite being attacked by a pack of 16 U-boats. The escorts even managed to kill two U-boats and damage a further five.

Despite a record 87 U-boats being deployed in the Atlantic during April only 12 ships were lost. Doenitz put this down to the inexperience of the crews and sent messages berating them but did nothing to change his tactics.

Throughout April battles around convoys ONS 5, HX 237 and SC 129 saw significant U-boat losses for little or no loss to the Allies. Convoy SC 130, which sailed on the 13th of May 1943, got through with no losses and three U-boat kills. On board one of those U-boats, U-954, was Doenitz’s own son Peter who was lost along with the rest of the crew.

In fact the packs attacked six of the seven large convoys in the Atlantic in mid-May and sunk six ships for the loss of 15 U-boats. By the 23rd of May almost a third of the U-boat Atlantic fleet had been lost.

On the 24th of May Doenitz acknowledged that the Allied advances in anti-submarine war had rendered the majority of his fleet obsolete. He withdrew his fleet from the North Atlantic convoy routes but promised they would be back when faster, better equipped U-boats were available. They never materialised.

In his memoirs, written 15 years later, Doenitz admitted that ‘Black May’ marked the German defeat in the battle of the Atlantic. While the war continued for another two years and both merchant and U-boat crews suffered losses, the U-boat was never again to enjoy the success it had achieved during the time of the wolf packs.

The loss of the battle of the Atlantic was mirrored by other German losses in Russia and Africa.

In May 1945 a thoroughly defeated Germany surrendered. On the 7th of May the following radio message was sent to all U-boat commanders, which was repeated every two hours: ‘Carry out the following instructions forthwith, which have been given by the Atlantic representatives. Surface immediately and remain surfaced. Report immediately in plain language your position in latitude and longitude and the number of your U-boat to the nearest British, U.S., Canadian or Soviet coastal wireless transmitter station. Fly a large black flag or blue flag by day. Burn navigation lights by night. Jettison all ammunition, remove breechblocks from guns and render torpedoes safe by removing pistols. All mines are to be rendered safe. Make all signals in plain language. Follow strictly the instructions for proceeding to Atlantic ports from your present area, given immediately following message. Observe strictly the orders of Allied representatives, to refrain from scuttling or in any way damaging your U-boat.’

At the end of the war 154 U-boats were surrendered to the Allies. Of these, 121 were scuttled in the deep waters off the coast of Northern Ireland and western Scotland. Some were used as target practice for aircraft, submarines and ships. This marked the end of Germany’s defeated U-boat fleet.

So, why did the Allies win the battle of the Atlantic? By 1944 Germany had overstretched itself too far. It was fighting land and sea battles on too many fronts with not enough men and equipment. The U-boat arm was not immune to this fact. This, coupled with continued improvements of all aspects of convoy security and anti-submarine warfare, swung the battle of the Atlantic the way of the Allies.

The German U-boat fleet at the beginning of the war was tiny, with just 57 craft. Nine of these were lost in the first months of the war with just 18 being built in 1939. The situation changed little in 1940 with 50 being built but 24 being lost.

It’s only in 1941 when Hitler began to lose patience with his surface fleet that production was stepped up. In 1941, 199 U-boats were built with the loss of just 35. In 1942, 237 were built with a loss of 83. However some of the most bitter fighting in the Atlantic in 1943 meant that 242 U-boats were lost in comparison to 284 built. In 1944 and 1945 far more boats were lost than were being built.

In fact, 60% of all U-boats built were lost at sea. This was completely unsustainable. It is arguable that if there had been greater emphasis placed on U-boat building in the 1930s and very early 1940s enough U-boats would have been available to Doenitz to enable him to strangle the convoy system very early in the war and not have to face a situation where the Allies had made the developments needed to take the upper hand.

Another factor in this is that the U-boat crews at the beginning of the war were highly trained, close knit units who knew how to work well together. Many of these experienced men were lost and an increase in building and the need to man more vessels meant that many of the remaining crews were split up to join less experienced crews. Training was often rushed and men were promoted beyond their experience.

Out of the total 40,000 men who went to sea in German U-boats during World War Two, 28,000 were killed and another 8,000 taken prisoner of war. The career of a Kriegsmarine submariner was harsh, dangerous and usually short with many of them losing their lives on their first patrol.

Anti-submarine warfare had, by the summer of 1942, raced ahead of developments in the submarines themselves. Doenitz’s decision to run operations from Kernevel had been a brilliant one in 1940 but ultimately proved disastrous. He had always regarded his officers and crews as almost a family and the tiny team he kept at Kernevel simply did not have the expertise to move submarine warfare on.

The distance between Lorient and Berlin denied him access to the scientific and engineering experience he needed.

In comparison to the thousands of military and civilian personnel employed by the Allies in anti-submarine warfare, Doenitz’s little operation was technologically in the dark ages.

I’m going to now look very briefly at the technology behind the Allied success. HFDF stands for High Frequency Detection Finder and is more commonly known as ‘Huff-Duff’. It uses two or more radio receivers to locate the direction of a transmitter. The wolf packs relied heavily on radio contact to be able to work together and not get in the way of each others’ torpedoes. The constant chatter in the wolf pack suited Huff-Duff very well and enabled the escorts to pinpoint U-boats.

ASDIC is active Sonar. Sound is bounced down through the water and the depth of the reflection is monitored and used to locate submerged U-boats. Depth charges interfered with Sonar signals and allowed U-boats to escape. Later weapons such as Hedgehog and Squid rectified this problem.

Radar detected U-boats on the surface. It proved particularly useful when fitted to aircraft, who could detect the U-boat and stay above cloud cover until the last minute before an attack, thus not giving the U-boat a chance to dive.

A quick look at the weapons. Hedgehog was a projectile weapons system, which threw 24 special explosives hundreds of feet ahead of the attacking ship. As soon as they entered the water the explosives armed. They exploded on contact either with the U-boat or the bottom of the sea. By launching weapons ahead of the ship the explosions did not interfere with Sonar and allowed the ship to keep tracking the U-boat. Hedgehog was eventually replaced by Squid which was another projectile system.

Air support became vital for the safe conduct of convoys. The long range, American built Liberator bombers were ideally suited to this task. The first operational use of a Liberator was by Coastal Command in 1941.

Squadrons of Liberator aircraft operated from just outside Londonderry, Ballykelly in Northern Ireland, from Newfoundland and from Reykjavik in Iceland.

By 1943 almost all of the North Atlantic convoys had cover from one of these bases. In those areas where air support was not available from a base, aircraft carriers could be used. However they were in short supply and took longer to build than other ships.

In the interim period two options were used, CAM and MAC ships. A CAM ship was a catapult aircraft merchantman. The ship was fitted with a catapult to launch a single Hawker Sea Hurricane. After a launch the pilot either found land or ditched in the sea. Only nine combat launches were ever made with the loss of eight German planes and just one RAF pilot.

MAC stands for merchant aircraft carrier and these were large ships, usually bulk grain carriers or tankers, which were adapted to carry three Fairey Swordfish planes on open decks. Planes could take off and land on specially built runways on board and many successful operations were mounted from these ships.

A further advance in the war against the U-boat was the Leigh light. These high powered lights were fitted to the planes of the RAF Coastal Command. German U-boats had to surface to recharge their batteries and it was safer to do this at night when they were less easily spotted. Planes would fly towards the U-boats using radar and turn on the spotlight at the last minute, giving the U-boat again no time to dive. The Leigh light was successfully employed from mid-1942.

I have looked briefly at some of the battles, the ships, the U-boats, the technology and the tactics used in the battle of the Atlantic but behind all of this were the ordinary submariners and merchant seamen who manned these vessels.

The real cost of the battle of the Atlantic was the enormous loss of life on both sides of the conflict. Over 28,000 U-boat crew and 30,000 merchant seamen were lost in this conflict.

Ladies and gentlemen, thank you for coming.


  1. michael mc mahon says:

    My great-uncle, James Foster was lost off Cape Race, Nova Scotia in November 1941. He joined the Royal Navy in June 1940 . He was a gunner on the armed merchant ship SS Larpool whch sailed from Liverpool in October 1941. They were part of convoy ON-27 and her destination was Barbadoes. She became a straggler, and she was attacked and sunk by U-208 200 miles East of Cape Race. The captain and five crew were rescued and taken to Newfoundland. Eleven other crew were rescued by the Canadian Corvette Bittersweet and taken to Nova Scotia. My uncle James and 21-27 others, (the figures are disputed) were not so lucky. It has only been possible for us to remember James and other Irishmen who died, in recent years and it is an honour for me to be able to do so in whatever manner I can, publicly and privately. I salute him and all the other brave seamen who risked their lives or who lost them. God bless them all.

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