Terror in the deep: how Hitler's U-boats pushed Britain to the brink

On the night of 13 March 1944, the Greek-registered steamship SS Peleus was en route from Freetown to Buenos Aires when she was hit amidships by two torpedoes, launched by a German U-boat, U-852. The twin-masted merchantman, of around 5,000 tons, swiftly began to sink, her internal bulkheads ruptured by the detonations. Within three minutes, the Peleus disappeared below the surface, leaving the surviving members of her 39-strong crew clinging to rafts and flotsam in the darkness.

As sinkings go during the naval war, it was unremarkable, one might even say routine. But what followed would set it apart. Soon after, U-852 surfaced close to the debris field, hoping to identify her prey and glean some information. Her captain, 27-year-old Kapitänleutnant Heinz‑Wilhelm Eck, ordered one of his men – who spoke some English – to come up to the bow to question one of the survivors. After learning the identity of his target, Eck gave the order for U-852 to move away. But then he changed his mind.

Eck was nervous. Prior to his departure from port, he had been given a lecture from his superiors on the perils of passing through the Atlantic Narrows, around Ascension, and was told that all four of the previous patrols undertaken by his predecessors had ended with the vessels being sunk. Due to the heightened risk of air attack he was urged to take every precaution to avoid being spotted by enemy aircraft. Even debris from a sinking, it was stressed, could give away his position.

Calculating that he could be only some 200 miles away by daybreak, when the wreckage of the Peleus would doubtless be spotted, he made the decision to attempt to destroy the debris. He brought a party of his men up on deck and ordered them to open fire on the rafts and other debris with machine guns. In the moonless night, they were largely firing blind, but the operation continued for hours, with grenades being thrown and U-852’s anti-aircraft gun even being brought to bear.

The number killed by these actions is unknown, but only four members of the Peleus’ crew – three Greeks and a Briton – survived among the wreckage. Three of them would endure until they were finally picked up by a Portuguese steamer, more than a month later.

A bloody exception

It is often assumed that the brutal treatment of the survivors of the Peleus was somehow the norm: that U-boat crews thought little of brutalising, even of murdering, their victims. That certainly was the assumption of Doris Hawkins, a young British nurse who was torpedoed and then picked up by a U-boat in 1941. “We had heard so many atrocity stories,” she later wrote. “We feared a shower of machine gun bullets.”

It has often been assumed that U-boat crews thought little of brutalising their victims

Bearing in mind the atrocities that were routinely committed by German forces elsewhere in the war – especially in eastern Europe – this assumption is entirely understandable. But, if the written records are to be believed, it is also entirely wrong. The example of the Peleus was very much the exception. Indeed, it was the only documented example of a U-boat action in the Second World War resulting in a war crime.

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Sceptical readers might question this assertion – and rightly so. For one thing, it is well known that Hitler was instinctively secretive and had a preference for issuing verbal rather than written orders when dealing with sensitive matters.

Consequently, at the Nuremberg trials, the prosecution was keen to assert that the available documentary record of the U-boat war was somehow incomplete, or that mendacious amendments could have been made. More than that, given the brutality with which most branches of the German armed forces conducted their war, is it perhaps naïve to imagine that the men of the Kriegsmarine somehow managed to resist both the heat of the moment – and the bloodthirsty rhetoric of their superiors – and refrained from straying into barbarism?

Licence to kill?

At Nuremberg, Grand Admiral Karl Dönitz, the erstwhile commander of U-boat forces, rejected robustly the claims that the Germans had somehow covered up atrocities committed during the war at sea. Yet the testimony of Korvettenkapitän Karl-Heinz Moehle, former commander of the 5th U-boat Flotilla, suggested that the culture within the U-boat arm may have been less ‘clean’ than Dönitz was willing to admit.

Moehle’s testimony centred around the so-called Laconia Order, Dönitz’s instruction to his crews, issued in 1942, to refrain from assisting shipwrecked crewmen. When he asked his superiors about the implications of the order, Moehle was told that it was a coded instruction to kill survivors. And that’s how he passed it on to his officers, albeit with the caveat that each individual commander had to act according to his own conscience.

It is quite possible, then, that there were other atrocities committed by U-boat crews against stricken merchant crewmen, but that circumstances conspired to consign them to oblivion. Perhaps there were no survivors to tell the tale, or the perpetrators were themselves sunk later in their patrol. Absence of evidence, then, should not be confused with evidence of absence.

Nonetheless, it is striking that so few examples of atrocities committed by U-boat crews have come to light. And this should prompt the curious to seek to understand why. The reasons why commanders might have resisted the urge to kill survivors – assuming they felt it at all – would have been multi-layered and would doubtless have evolved with time. But a few explanatory factors are worth bearing in mind.

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For one thing, the typical U‑boat – such as the Type VII – was small and cramped. With its crew of around 50, it had no space to accommodate survivors and only limited capacity to offer material assistance. Bearing that in mind, it is remarkable how often, in the opening phase of the war, U-boat crews assisted the surviving crewmen from the ships that they had sunk, offering food, cigarettes, blankets and a compass bearing.

In the most astonishing example, the commander of U-35 opted to take the 28 surviving crewmen of the Greek-registered Diamantis aboard his submarine and sailed more than 30 hours to the beach at Ventry, in western Ireland, where they were then ferried ashore in a dinghy.

Such chivalrous actions could scarcely survive in the age of total war, of course, and after the Laconia Order, all such humanitarian impulses were formally banned by the German naval command. As a result, after the initial phase of the war, contact with survivors was effectively forbidden. By mid‑1942, then – aside from a brief interrogation to confirm the identity of the sunk vessel – U‑boats tended to avoid survivors altogether.

The culture within the U‑boat arm is also worth consideration. One should be wary of underestimating the influence of ideology in any arm of the Nazi state, but it is notable that even contemporaries considered that the Kriegsmarine was less ideologically aligned with Nazism than other branches of the armed forces. Hitler himself is said to have complained that he had “a Nazi air force, a Prussian army and a Christian navy”.

Hitler is said to have complained that he had “a Nazi air force, a Prussian army and a Christian navy”

That quotation, though apocryphal, may nonetheless have had the ring of truth. Crewman Hans Goebeler, aboard U-505, recalled that – on his boat at least – ideology simply didn’t seem to matter: “Who were the Nazis aboard our submarine?” he asked: “I never met one. We were identical to the sailors from every nation who faced the hazards of war and the sea during those years. Party members or not, we performed our duties with professionalism and honour.”

Every boat would have had a cross-section of German society aboard, from fervent Nazis to the apolitical and even those who opposed the regime. Yet the question of how far the U-boat arm was indoctrinated is an interesting and complex one.

Dönitz himself was a convinced Nazi, who was fiercely loyal to Hitler, and a few of his commanders shared that enthusiasm. But active indoctrination of the U-boat arm appears to have been limited. While other branches of the German armed forces were increasingly subjected to ideological control as the war progressed, this was simply not the case for the navy.

Despite his own enthusiasm for Nazism, Dönitz appears to have stopped short of establishing genuine ideological oversight over his men. The office responsible for indoctrination within the navy, for instance, was staffed largely by men without Nazi backgrounds and – given that they were also not permitted to ‘ride along’ on patrol – they were in any case prevented from exerting any real influence over operational units.

This doesn’t mean that the U-boat arm was some sort of haven for anti-Nazi thinking or oppositional attitudes. It was not. The Kriegsmarine was far from apolitical, but its leaders held the view that its coordination to Nazi goals was self-evident, a natural corollary to the patriotism and sense of duty that were essential components of their collective identity. Dönitz held the attempts to enforce ideological conformity at arm’s length, not because he disagreed or was minded to resist, but because he considered such measures to be an unnecessary imposition. The Kriegsmarine, he believed, was already wholly on side.

We should also keep in mind that there was no single ‘way of war’ practised by the forces of the Third Reich in the Second World War. The murderous methods deployed on the eastern front, for instance, were only rarely in evidence in the west, while the war in the desert, lacking an ideological dimension, tended to be similarly unsullied by atrocities. These differences in behaviour by German forces were not the result of whim or happenstance. Rather, they were contingent on the nature of the enemy and whether Nazi ideology deemed them to be civilised and worthy of respect – as in the west – or to be subhumans slated for extermination, as in the east.

The available evidence shows that the naval war, and the submarine war in particular, cleaved more to that western model than to anything else. It is hard to escape the conclusion that the U-boat war does indeed appear to have been the ‘cleanest’ of the theatres of the European conflict, with many more instances of the old fashioned ‘solidarity of the sea’ in evidence than there were examples of atrocities.

Moral outrage

Such logic cut little ice with the judges at Nuremberg, of course, as Dönitz was found guilty on two of the three charges against him and was sentenced to 10 years’ imprisonment. As the former commander of the Kriegsmarine, and Hitler’s successor as Reich President, he deserved neither leniency nor sympathy. And, in the first flush of moral outrage over the crimes of Nazism, the Nuremberg judges were inclined towards the view that all Germans were Nazis and that everything that German forces had done was evidence of Nazi barbarism.

Nonetheless, it was a verdict that provoked no little controversy, even from some senior Allied naval officers. US Admiral Daniel V Gallery – who had spent most of the war hunting U-boats – was especially vociferous in his condemnation. Dönitz’s trial, he said, was an “outstanding example of barefaced hypocrisy”, and his conviction was “an insult to our own submariners”. “If the old gentleman ever gets out of jail,” he wrote, “I hope I never meet him. I would have trouble looking him in the eye. The only crime he committed was the crime of almost beating us in a bloody but ‘legal’ fight.”

He had a point. Dönitz’s defence at Nuremberg – brilliantly conducted by his lawyer, Otto Kranzbühler – had turned largely on the apparent hypocrisies of the Allies’ accusations, given that they, too, had effectively been carrying out unrestricted submarine warfare for most of the war. To hammer home the point, Kranzbühler had produced an affidavit from Admiral Chester Nimitz, wartime commander-in-chief of the US Pacific Fleet, which asserted that it had been customary for US submarines to attack Japanese merchant ships without warning, and that ‘general principles’ did not permit US submarines to rescue enemy survivors. In short, Nimitz’s testimony implied that the US Navy had conducted its submarine war precisely as Dönitz claimed to have conducted his.

The truth on this point was more damning than Kranzbühler could have known. Naval records released in the 1960s would reveal that the crew of the American submarine USS Wahoo had themselves participated in an action not unlike that involving the Peleus. In January 1943, the Wahoo sank the 5,000-ton Japanese troopship Buyo Maru, north of Papua New Guinea, which had been carrying Japanese soldiers and nearly 500 PoWs from the British Indian army. In the aftermath, as Japanese and Indian survivors bobbed around some 20 lifeboats, the crew of the Wahoo opened fire with machine guns. “We proceeded to have a field day,” said the captain, Lt Commander Dudley Morton.

Biological hatred

In his defence, Morton claimed that he was returning fire, but this is disputed. Some of his crew were even shocked by his evident “biological hatred” of the enemy. Whatever justification he felt he had, Morton’s attack on the Buyo Maru cost the lives of some 87 Japanese soldiers and more than 195 Indians. His after‑action report included the shooting, but he faced no punishment, and the incident was suppressed by his navy superiors. In postwar narratives, the example of the Buyo Maru was quietly forgotten, while that of the Peleus would be held up as symbolic of Nazi brutality.

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This is not a game of moral equivalence. It would be wrong to draw from a few isolated cases the false conclusion that the Allies and Axis were morally indistinguishable. The broader war aims mattered. However ‘clean’ the U-boat campaign may have been, it was serving a regime synonymous with evil. Conversely, even when the Allies faltered morally, their cause – resisting tyranny – remained just.

The point, rather, is to challenge the lazy assumption that German U-boat crews were sadistic murderers. The Peleus atrocity was very real, but it was an outlier. U-boats dealt devastating blows to Allied shipping and caused enormous loss of life, but there was only one confirmed instance of the deliberate killing of survivors.

The murder of the Peleus survivors was not a feature of the U-boat war. It was a chilling, singular exception.

Britain's near-death experience

How U-boats drove a nation to the brink of economic strangulation

During the early years of the Second World War, Britain came perilously close to defeat in the Battle of the Atlantic – a prolonged struggle against German U-boats aiming to sever the maritime lifelines sustaining Britain. As an island nation dependent on imports for food, fuel and war materiel, Britain faced an existential threat from the Kriegsmarine’s submarine campaign.

Between 1939 and 1945, German U-boats sank more than 2,700 Allied merchant ships, totalling approximately 14.5 million gross tons. The most dangerous period came in 1942, when 1,160 ships were lost to U-boats– more than 6.2 million tons – much of it along the poorly defended US coast during Operation Drumbeat.

Britain’s shipping losses outpaced production for much of 1941–42, and food rationing became more severe. At one point, Britain had only six weeks’ worth of grain reserves. Winston Churchill later wrote that the U-boat threat was the only thing that truly frightened him during the war.

The crisis peaked in early 1943, when monthly merchant shipping losses reached around 700,000 tons. German Admiral Karl Dönitz believed victory was within reach, committing more than 100 U-boats to mid-Atlantic ‘wolfpack’ operations.However, from May 1943 – dubbed ‘Black May’ by the Germans – the tide turned. Allied advances in radar, sonar, Ultra intelligence, long-range patrol aircraft and escort carriers decimated U-boat fleets. That month alone, the Germans lost 41 U-boats, forcing a temporary withdrawal from the Atlantic.

Though never completely severed, Britain’s shipping routes were 

strained to their limits. Without technological breakthroughs, convoy reforms and American shipbuilding – producing Liberty ships faster than U-boats could sink them – Britain might have been economically strangled into submission.

In the end, the U-boat campaign claimed the lives of more than 30,000 Allied seamen. But it failed to deliver a knockout blow.

How the Allies turned the tide

A timeline of the war against the U-boats

3 September 1939: The British liner SS Athenia is sunk by U-30 just hours after Britain had declared war on Germany, marking the start of the Battle of the Atlantic

14 October 1939: U-47 penetrates Scapa Flow and sinks the battleship Royal Oak, killing 833, shocking the Royal Navy and boosting German morale

June 1940: Following France’s fall, Germany gains Atlantic U-boat bases at Lorient, Brest and elsewhere. This dramatically extends U-boat reach into the Atlantic and intensifies Allied shipping losses

March–June 1941: U-boats enjoy high success against British shipping, aided by poor Allied convoy tactics and limited air cover, marking their most effective early-war period

12 September 1941: U-156 sinks RMS Laconia carrying civilians and PoWs. After surfacing to help survivors, the U-boat is attacked by US aircraft. This prompts the Germans to introduce the Laconia Order, forbidding the rescue of survivors

October 1941: German U-boats operate in coordinated ‘wolfpacks’ to attack convoys, reaching peak effectiveness in the mid-Atlantic and causing severe shipping losses, despite increased Allied defences

December 1941: Following Pearl Harbor, U-boats begin Operation Drumbeat, targeting unprepared US coastal shipping. This results in catastrophic losses early in 1942

May 1943: In what the Germans will dub ‘Black May’, the Allies turn the tide with improved radar, codebreaking and air cover. U-boat losses spike dramatically, forcing Germany to temporarily withdraw many boats from the Atlantic

June 1944: U-boats fail to disrupt Allied landings in Normandy. With air superiority, improved technology and better escorts, the Allies dominate the Atlantic, further reducing U-boat effectiveness

5 May 1945: Admiral Dönitz orders all remaining U-boats to surrender. More than 150 comply, marking the official end of the U-boat war and the wider naval conflict in Europe

This article was first published in the November 2025 issue of BBC History Magazine