The U-Boat Campaign

Many would agree that no single factor contributed more to the Allied victory in the Second World War—or was more important—than the long, hard-fought, extraordinarily punishing campaign to keep the oceans open to the vital shipping traffic, without which Britain could not have survived and the Russian allies could not have successfully prosecuted the war from the East. Without that challenging and desperate campaign, Britain could not have provided the springboard for the Normandy invasion.

The real heroes of the campaign were the largely unheralded, mostly forgotten seamen of the British Merchant Navy, the American Merchant Marine, and the Canadian Merchant Navy. Their astonishing courage and unparalleled devotion to their duty in the most outrageous and intolerable of conditions, and under nearly constant menace by enemy submarines, aircraft and surface warships, is to their everlasting credit. That is, of course, not to take away from the performance of the gallant escort crews, both naval and air, who, for much of the conflict were often super-human in their performance and achievements.

It is important, too, to note the invaluable and wide-ranging aid provided to Britain from both the United States and Canada in the form of the “Cash and Carry” and “Lend-Lease” programmes, the destroyers made available as well as the Liberators and Flying Fortress bombers, and the American and Canadian participation in the convoys in various roles including the crucial escort duty. It must be said that the British returned the favour many fold with their provision of escorting armed trawlers, their experience of escort tactics, their Ultra intelligence information, and their HFDF (Huff Duff) high frequency direction finding technology.

The value and contribution of the very long-ranging aircraft equipped with new state-of-the-art radar cannot be overstated. It finally closed the gap in the mid-Atlantic, enabling the Allies to reach, locate, attack, and destroy the U-boats and surface warships of Germany anywhere in the vast seas. And with the variety of weather conditions prevailing along the shipping lanes, the proficiency and effectiveness of the new radar in the long-range bombers tipped the odds much more in the Allies’ favour. Even so, the results showed that the “huff duff” technology and the human eye did, in fact, detect more enemy submarines than any other technologies of the period. Admiral Dönitz over-estimated the importance of the Allied radar, thanks mainly to being ill-advised by his scientists, and as a result took precautions against it that were largely ineffective. The combination of centimetric radar and the enormous and very timely growth of air power then turned the sea lanes into a U-boat killing ground.

Yet another vital contribution to the success of this major Allied campaign was that of Commander Frederick John “Johnnie” Walker, whose offensive team tactics against the U-boat wolfpacks had, by 1943, been adopted by the Royal Navy as well as the U.S. Navy’s hunter-killer groups. For the sailors aboard Walker’s Black Swan-class sloops, high seas operations were often testing affairs (even the hardiest sailor could feel queasy in a sloop), but the vessels were highly manoeuvrable and, in action, reminded him of hounds on a scent. When his sloop, HMS Starling, sailed from the historic port of Liverpool, he had “A-hunting We Will Go” played loudly on the Tannoy to inspire the crew. In the course of the campaign, Walker’s No 2 Support Group attacked and sank twenty-one U-boats, downing six of them in a single operation. He himself was credited with the destruction of U-264, the first snorkel-equipped U-boat to become operational.

Sharing kudos for their triumphs in the field of U-boat killing was Captain Donald Macintyre.

Finally, the role of intelligence and the valuable contribution that was provided about the U-boat movements thanks in large part to the amazing cryptographers at the British Government Code and Cypher School, Bletchley Park, Buckinghamshire, must be acknowledged. Without question that contribution was absolutely key to Allied victory in the war. Ultra was the code-name for intelligence information that resulted from interpreting the high-grade codes and the cyphers collected, collated, and then disseminated by the Signals Intelligence Branch of GC&CS at Bletchley (now GCHQ in Cheltenham), which obtained the information by eavesdropping on enemy communications.

The challenge for the Signals Intelligence people was that securitygraded radio traffic within the German armed forces was protected by the use of a sophisticated enciphering machine, Schlüssel M, also known as Enigma. In the use of Enigma, a message was typed on an ordinary keyboard and then passed through electrical circuits to three rotors which had separate contact points for each letter of the alphabet in a scrambled order. As the operator typed it, each letter of the message was transmitted in turn to the first, second, and third rotor, changing each time, until the enciphered letter to be used by the operator was displayed on a screen above the keyboard and then transmitted in Morse code. At the receiving end, an operator with a similar device and a list of the rotor settings for the day, simply went through the enciphering routine in reverse. As the rotors could be changed at will, and the number of electrical circuits could be increased, the variations possible verged on the infinite. The machine was compact and simple to operate, and the resulting code was virtually impenetrable.

Appropriated by the government for the duration of the war, the Bletchley Park House property incorporated a series of huts, Nissen and others, within the grounds and these were inhabited by the Bletchley code-crackers—academicians, crossword puzzle experts, chess players—who applied themselves hour after hour to the job of unscrambling the Enigma codes. They were initially unable to distinguish a pattern as they listened to the mass of German radio traffic. Not only did each branch of the enemy forces have its own Enigma rotor settings, the naval code, which was known as Hydra, was changed daily. The computer devices then available to the Bletchley folks, while enormous in physical size, were actually less powerful than most current laptops.

Help finally came, from Poland, where one of the early versions of the Enigma device had been built and the Polish intelligence service had monitored its development. They had supplied information about that development to the British government in London, but the Bletchley people desperately required more detailed information about Enigma’s codes and rotors. To that end, the Royal Navy was assigned the task of capturing an enemy vessel with the Enigma device, codes, and any associated papers etc on board.

In February 1940, the Navy managed to capture the U-33 which was mine-laying in the Firth of Clyde; that act produced three Enigma rotors. The incident was followed by one a month later when cipher papers and another rotor were confiscated from the armed trawler Krebs, and on 7 May 1941, when code settings for the coming three months were found aboard the weather ship München. After each of these incidents the government announced, for the benefit of German ears, that the ships had sunk before they could be boarded. But the important break for Bletchley came on 9 May when U-110, the U-boat commanded by Kapitänleutnant Fritz-Julius Lemp, chose to attack two merchant vessels off the coast of Greenland, with a fan of three torpodoes. Lemp is the U-boat commander who, as skipper of U-30, had been severely reprimanded after torpedoing and sinking the passenger liner Athenia on 3 September 1939, claiming later that he thought the ship was an armed merchant cruiser.

Lemp in U-110 was just under the surface near the convoy when his periscope was spotted by a lookout on an escorting warship. The submarine was immediately attacked by the corvette HMS Aubretia with depth-charges and was forced to surface, where she received heavy gunfire from Aubretia and two other warship escorts. Lemp and most of his crew then abandoned the sub.

As the destroyer HMS Bulldog approached to ram the U-boat, her captain elected instead to capture it intact. He sent an armed boarding party aboard and they located and retrieved the Enigma machine and code books. King George VI later described the incident as “the most important event of the war at sea.” With Enigma and many of its secrets now in the possession of staff at Bletchley Park, they were able to read the German Hydra naval code, but they were determined that the Germans not know they could read it, and all those who had been involved in the capture of U-110 were sworn to keep silent about it, a silence which held for the next thirty years.

The Ultra intercepts were keeping the British informed and for the next nine months the positions of all operating U-boats were plotted in the Submarine Tracking Room of the Admiralty. In February 1942, however, the Hydra code was altered. It was simply a routine change and not because Dönitz suspected that the British had broken it. In the next three months, sinkings of Allied merchant ships doubled. Another change came about in spring 1943, when the Germans added a fourth rotor to Enigma, giving the Bletchley people a two-week headache while they struggled to cope with the new wrinkle. In that span, two convoys bound for Britain from New York lost a total of twenty-two merchant ships to the U-boats. From then on, though, the information provided by Ultra from Bletchley was magnificent. Churchill referred to Ultra as “the precious secret.”

Now the days of U-boat success were indeed numbered. In the massive effort to overcome the German submarine menace, the Allies were investing more than a hundred thousand men, more than forty aircraft carriers, and hundreds of escorting destroyers, corvettes and sloops. And while Allied merchantman losses continued—twenty-four of the ships were sunk between September and December 1944—the action cost the Germans fifty-five U-boats. It didn’t require much imagination for the surviving commanders of the Ubootwaffe to realise and accept that they were beaten.

The battle had been long, arduous, and costly to both sides, and both sides had fought bravely, steadfastly, and, in general, with a degree of honour. There were exceptions, however, such as an instance of a sinking U-boat’s crew being fired on in the water by a British submarine, and another, in 1944, of a U-boat’s guns being turned on the lifeboats of a torpedoed Greek freighter. For the two commanders who were responsible for these actions, the outcome exemplified the difference between being on the winning and losing sides in war: the Royal Navy officer received a decoration—albeit for another and more worthy feat—while the U-boat commander, Kapitänleutnant Heinz Eck, together with four of his crew, was tried by court martial, found guilty of a war crime and shot by a British firing squad on 30 November 1945.

The Royal Navy killings were largely forgotten, but the U-boat incident was turned into a cause célebre. Some believe that the British used it to try to convince the Nuremberg Tribunal that Admiral Dönitz had condoned such brutalities, and as such, was guilty of a war crime. The ploy, if that be true, did not work. The admiral was deprecating of the act and offered a reasonable excuse: his commanders were expected to eliminate the wreckage on the water (not the seamen), so that no trace would be left that might assist the escort warships to hunt down the U-boat. The tribunal judges weighed the evidence and, relative to the possible commission of a war crime, found in favour of the admiral.

There were also times when U-boat commanders came alongside a lifeboat to learn the name and tonnage of the vessel they had sunk, and then given sustenance to the survivors, in the form of cigarettes, cognac, and sometimes a course to steer for land. In his book, Convoy, Martin Middlebrook refers to an instance in which a U-boat surfaced and the men in lifeboats heard a voice through the darkness asking if they needed food. Wary of a trap, the seamen did not answer. Moments later, they heard the voice again. “Goodnight, British”, Otto Kretschmer called, and U-99 stole silently away. It was true that Admiral Dönitz had given his commanders orders that only downed airmen—who might give useful information—were to be rescued from the sea, and, considering the crowded conditions in a U-boat, this was reasonable enough, but there was never any proof that he approved the slaughter of survivors. Few U-boat commanders would attack an escort ship while it was picking up seamen from a stricken vessel, but this was not entirely for altruistic reasons: an escort so involved was one less available for offensive action.

In the dark night of 16 March 1942, the lone merchant ship SS Allendi, was steaming near the Ivory Coast of West Africa, making for Freetown to join with a convoy bound for Britain. The crew heard what they thought to be the sound of diesel engines and suspected it might be a surfaced U-boat charging its batteries. Early the next day their ship was struck by a torpedo and began sinking. Frank Lewis, Chief Radio Officer, SS Allendi: “The skipper came into the radio cabin and said it was time for us to get into the one remaining boat. We lost no time, for the ship was riding very low in the water by then. A good thing we did, too, because we had not pulled very far away when another torpedo struck her and she disappeared in just a few minutes. There we were, thirteen in a small jollyboat that was damaged and water-logged.” The U-boat commander then came alongside and gave them the choice of staying where they were or being taken back to Germany as prisoners of war. Most of the men in the jollyboat were Merchant Navy officers and they decided to take their chances where they were. Lewis: “When the U-boat left us, she created such a wash that our boat overturned, and we were left swimming. We had just managed to clamber on to the upturned boat when the next wash came along, righted the boat and threw us back into the water.” History showed that the Merchant Navy men made the right choice. They made their way to the Ivory Coast thirty-six hours later and eventually back to England.

The Allied invasion of the European continent in June 1944 was something less than the best kept secret of the war. Most Germans in the armed forces were well aware that it was in the offing and many had a pretty sound idea about where the Allies would likely be landing along the French coast. The more confident among them were persuaded that the Wehrmacht would be able to repel the invaders and shove them back into the sea before they could gain a foothold, and those who did manage to get ashore would be wiped out in the withering gunfire that would come from Hitler’s vaunted Atlantic Wall defences along the coast. Those in the German High Command were less sure, however, about where the invasion forces would be landing and what the result might be. In the opinion of the German Army Commander in the West, Feldmarschall Karl Gerd von Rundstedt, the Allied forces would opt for the shortest route across the English Channel, to the Pas de Calais. Feldmarschall Erwin Rommel, who would command the German forces opposing the Allied cross-channel invasion, was convinced that the Normandy coast was where the action would occur. He was completely persuaded that the Allies must be beaten on the beaches or Germany would lose the war.

In numbers, von Rundstedt’s command amounted to fifty-eight divisions spread along the coastline and behind it, from the hook of Holland to the Spanish border. That number was an illusion though, as the enormous casualties the Germans had experienced on the Russian Front had effectively reduced his fighting strength to the equivalent of less than thirty divisions. What could the Germans hope to mount in the way of air defences? Due to several months of USAAF and RAF concentrated attacks, and the work of swarms of Allied fighters, the strength of the Luftwaffe was greatly reduced and it was desperately short of pilots, fuel, and serviceable aircraft. And with the weakening and downgrading of the German surface navy, Dönitz had to rely on what was left of his U-boat force to take up the slack and do its part in fending off the Allied effort. He later wrote in his memoirs: “Every vessel taking part in the landing is a target of the utmost importance which must be attacked regardless of risk. Every boat that inflicts losses on the enemy while he is landing has fulfilled its function even though he perishes in so doing.” There was no denying that this newly dictated role for Germany’s formerly key weapons of attack was the last gasp of warriors on the defence.

The Allied invasion of Europe was code-named Operation Overlord, and to oppose it, the surviving U-boats of Admiral Dönitz’s force numbered sixty-one in the Bay of Biscay bunkers and twenty-two in the Norwegian fiords. Of the fifteen boats berthed in the pens at Brest that May, one was U-415, that of Oberleutnant Herbert Werner: “The order was to attack and sink the invasion fleet with the final objective of destroying enemy ships by ramming.” At midnight on 6 June U-415 was one of eight U-boats that slipped out of the huge Brest bunker and joined with an escort force of patrol boats and armed trawlers. Werner recalled that his orders were to proceed at top speed on the surface to the south coast of England, there to carry out the admiral’s command, suicidally, if necessary. His boat would return to Brest two days later, badly damaged and one of only three boats to survive the mission. There had never really been much hope for the success of the small force of remaining U-boats against some 800 Allied warships and 4,000 landing craft. Werner later wrote: “By 30th June, U-boat operations since the invasion began were a full-fledged disaster. We had sunk five Allied cargo ships and two destroyers, and we had lost twenty-two U-boats.”

To consider the capability and potential contribution of the U-boat fleet relative to the Allied D-Day cross-channel invasion, it is essential to remember that the U-boat was planned, designed, and constructed as a strictly offensive weapon and was never intended for defensive use. The primary focus of its mission in the war, as laid out by Admiral Dönitz, was the mid-ocean anti-convoy attack, preferably by wolfpack teams of U-boats. Substantial priority was not given to development of a specific submarine type or types dedicated to more tactical and defensive roles such as coastal ambush. Thus, when thrust into a defensive challenge in the months leading to the D-Day invasion, Dönitz and the men of the Ubootwaffe could no longer realistically anticipate victory, only the possibility of honour in defeat.

At 6:30 a.m., Tuesday, 6 June 1944, amphibious landings by Allied forces commenced along five key beaches of the Normandy coast. The landings were preceded with an airborne assault by 24,000 American, British, Canadian, and Free French troops shortly after midnight. A combination of inclement weather and a clever deception plan put into effect in the months preceding the invasion, aided the Allies in achieving the hoped for strategic and tactical surprise elements. Key to this was the effort to make the Germans believe that the invasion forces were to be led by General George Patton across the Straits of Dover to Calais. The ruse was so persuasively maintained even after the D-Day landings that Hitler was sufficiently convinced of that threat as to be unwilling to reinforce his troops in Normandy with forces positioned to defend the Pas de Calais.

The Allied command structure was in the charge of the American General Dwight Eisenhower, the Supreme Commander of the Allied Expeditionary Forces, with the British General Bernard Montgomery having overall command of the ground forces. It was the largest amphibious invasion in history, comprised of 73,000 American 61,715 British, and 21,400 Canadian troops, 195,700 Allied naval and merchant navy personnel, 4,000 ships and landing craft, and thousands of aircraft. The actual landings were made along a fifty-mile front, with the Americans assigned to Omaha and Utah beaches, the British to Gold and Sword beaches, and the Canadians to Juno beach. There were no U-boat attacks against Allied shipping on D-Day.

Effectively, U-boats were not involved in the English Channel on D-Day, and in the days that followed, were never able to impact the Allied effort. By late August, German emphasis was on saving the surviving U-boats by withdrawing them as much as possible to Norway and Baltic ports.

The rolling thunder of American tanks entering Brittany was joined by the pounding of R.A.F. bombs on the U-bunkers of Brest, St Nazaire, Lorient, La Pallice and Bordeaux. By September, Brest was under siege and surrounded by the American 6th Armored Division. Those U-boats remaining in the Biscay bases were dispatched on a hazardous six-week journey around the coast of Ireland, through the North Channel and past the Orkney and Shetland Islands, harassed all the while by Allied planes and warships, to eventually reach anchorage in the Bergenfiord on the southwest coast of Norway. Memories of the cafés and promenades and the sunshine they had left behind contrasted starkly with the glacial landscape, gloom, fogs and gray seas where they were now holed up, symbolic of the depressing decline in the fortunes of the Ubootwaffe. The retreat from France marked the end of their effective role in the Second World War.

The propaganda line out of Berlin trumpeted the great new assault by Germany’s V-2 terror rockets on England, and coming soon to America as well, guaranteed to make the Allies sue for peace. More credible, perhaps, was the impressive December offensive by the Germans in the lush hills of the Ardennes in Belgium, France and Luxembourg on the Western Front, known today as the Battle of the Bulge. This massive German counter-offensive was aimed at splitting the British and American Allied line in two, capturing Antwerp, encircling and destroying four Allied armies, and then forcing the Western Allies to negotiate a peace treaty in favour of the Axis powers. Once accomplished, Hitler would then be free to refocus on Russia. Initially, circumstances favoured the Germans. Poor aerial reconnaissance due to exceptionally bad weather conditions, Allied overconfidence, and preoccupation with their own offensive tactics, left the Allies surprised by the enemy offensive even though intelligence personnel in Patton’s Third Army had predicted it.

The then vastly superior Allied air forces had been grounded by the heavy overcast weather, but gradually the weather lifted and that, coupled with outstanding resistance around the town of Bastogne, and the renewed ability of the Allies to bring in supplies and reinforcements, turned the tide and ended the German offensive. It was the largest and bloodiest European land battle of the war.

Hitler took personal command of Berlin’s defences in February 1945. In April the American president Franklin Roosevelt died and he was replaced by Harry Truman, who was no less dedicated to the defeat of Nazi Germany. On 1 May the death of Hitler was announced: “Our Führer, fighting to his last breath, fell for Germany in his Headquarters . . .” Days later, at the end of the war, the Nazis planned to scuttle their fleet (as they had done at the end of the First World War), including the remaining U-boats, but the British stipulated that no such action be taken, otherwise the bombing of strategic targets in Germany—or what remained of them—would go on. Dönitz was left with no choice, and on 5 May he ordered all U-boats to transmit their positions in plain language and sail to Allied ports: “Unbeaten and unblemished, you lay down your arms after a heroic fight without parallel.”

At that point Germany still had more than 350 U-boats, including many new Type XXIs and XXIIIs, which had never been in action. The majority of these boats were in German ports or at anchor in the Norwegian fiords. Some remained at sea and of these, two were sailed to Argentina, while the rest went to Britain and America where they were surrendered. Nearly 200, however, in the hands of commanders who either did not believe the order of their Admiral, or refused to accept it, were scuttled by their crews. Of the 156 U-boats surrendered by September 1945, 110 were scuttled or sunk by Royal Navy gunfire off the coast of Northern Ireland. Nearly 30,000 of the 39,000 German sailors who went to sea in the U-boats never returned.