B-Dienst had correctly forecast that an Allied landing would take place in the south of France although the exact location and date were not known. As a preliminary, the Allies made heavy raids against the German-held ports of Toulon, Genoa and Trieste, resulting in the sinking of many merchant ships and small warships. On 6 August the US Fifteenth Air Force raided Toulon once more and succeeded in destroying four U-boats, all of which had been damaged in a previous raid, and further damaging a fifth. The Allied landings took place on 15 August with French and American divisions and were successful everywhere. The Germans had no option but to to scuttle or blow up three of the remaining U-boats, all of which had been damaged previously. Only three U-boats remained in the Mediterranean, all based at Pola.
Three days after the landings in the south of France, Hitler ordered the U-boats in Brest, Lorient, St-Nazaire, La Pallice, La Rochelle and the Gironde to evacuate their ports and to head round the north of Britain to Norwegian waters. It was clear that these French ports would soon become unusable with the advance of the Allies from the north and the south. The move was also accelerated by the knowledge that the RAF was by then capable of breaching the immensely thick roofs of the U-boat shelters. On 12 August Lancasters of Bomber Command dropped the new 12,000 lb ‘Tallboy’ bombs on the shelters at Brest, penetrating part of the roof. Eight U-boats which were unfit for the journey to Norwegian ports were either scuttled or scrapped. The French ports were not to be evacuated by ground personnel, who were ordered to defend them as ‘fortresses’ against the Allied troops.
Apart from the seven U-boats destroyed in the Mediterranean and the eight scuttled in French ports, twenty-one others were lost during August for various reasons, mainly sunk by air attack while on war cruises. The U-boat Arm succeeded in sinking eighteen merchant vessels amounting to about 99,000 tons during this month, from a total of 118,500 tons lost by the Allies, but it was continuing to fight a losing battle. By this time new shipbuilding of merchant vessels in America and Britain had reached about 38 million gross tons since the beginning of the war, whereas total sinkings had amounted to about 23 million tons, of which about 14.5 million tons had been sunk by U-boats. Moreover, further production was proceeding at an accelerated pace, whereas the pace of sinkings was declining sharply.
The decline of the U-boats continued into September, for they sank only seven merchant vessels amounting to 43,000 tons, apart from which the Allies lost only one vessel which struck a mine. The slaughter of the U-boats continued, for they lost twenty-one of their number during the month. Three of these were scuttled after being transported in sections from the Baltic to the Black Sea, where they were reassembled. The advance of the Red Army threatened to cut them off. The three remaining U-boats in the Mediterranean were also destroyed, one sunk by destroyers north of Crete and the other two during an American bombing raid on Salamis in Greece, where they were sheltering. Henceforth, the U-boat Arm could operate only from bases in Norway. It was reduced to 144 operational boats by the end of the month, with 260 more undergoing training and trials.
The giant battleship Tirpitz was badly damaged again on 15 September. On this occasion the attacking force consisted of twenty-eight Avro Lancasters of RAF Bomber Command operating from North Russia. Twenty-one of them were carrying the huge Tallboy bomb. The bombers arrived in daylight over Kaa fjord, flying between 6,500 and 10,000 feet, and achieved initial surprise. One of the Tallboy bombs scored a direct hit and blew a great hole in the bows and the side. Other bombs scored near misses and caused further damage. German marine engineers concluded that repairs would take about another nine months. A month later, after work on her engines, she steamed about 200 miles south-west to Tromsö to act in a new role as a flak battery.
October brought no improvement in the circumstances for the U-boat Arm. Although replacements were still pouring through the system, the number of operational boats had been reduced to 141, with 260 under training and trials. Eleven U-boats were sent from Norway to operate off the west coast of Britain, in waters such as the English Channel, the Bristol Channel and the North Channel. Four others were dispatched to waters off Newfoundland and another off Gibraltar, but the achievements of the entire U-boat fleet were limited to the sinking of only one merchant vessel of about 7,000 tons during October, while three other Allied vessels were sunk from mines. In return, eleven U-boats were lost, four of them in a raid by RAF Bomber Command on the pens at Bergen and another during a similar raid on Wilhelmshaven.
November was little better for this hard-pressed service, for the U-boats sank only seven merchant vessels totalling about 29,500 tons from an overall figure of 38,000 tons lost by the Allies from all causes. However, the number of U-boats sunk fell to eight, perhaps indicating that the commanders were becoming more skilled with the use of schnorkels and evasion techniques. The inshore campaign in waters off the west coast of Britain was causing some difficulty for the Admiralty, for there were insufficient anti-submarine vessels to hunt in these waters. The U-boats seldom appeared on the surface during daylight and were difficult to detect by Asdic when submerged among offshore rocks. RAF Coastal Command hunted for them, but often fruitlessly in daylight hours.
November was the month which saw the end of the battleship Tirpitz, partly because her new location brought her within the range of RAF Lancaster bombers operating from Scotland. Twenty-nine of these took off from Lossiemouth on the night of 11/12 November and arrived individually over their target during daylight. The battleship received direct hits from at least two Tallboy bombs and then suffered a huge internal explosion. She capsized and came to rest upside down at the bottom of the fjord, killing 1,204 men from her crew of about 1,900. This action removed a major threat to the Arctic convoys, which henceforth experienced only spasmodic attacks from U-boats.
It must have been obvious to Dönitz that his U-boats were fighting a losing battle in the Atlantic and elsewhere, and yet he continued to throw all available resources into the conflict. Senior officers in the Wehrmacht nurtured the belief that their country possessed a technical superiority capable of producing ‘wonder weapons’ that would enable them to gain ultimate victory. Examples were the V-1 flying bomb, the V-2 long-range rocket and the Messerschmitt Me262 jet aircraft. Within the Kriegsmarine, it was the new ‘electro-boats’. These were being built as a compromise for the Walter Type V boat which had been considered impracticable. An engineer on this project, Heinrich Heep, had recommended that the lower of the two tanks, originally intended to hold concentrated hydrogen peroxide, should be utilised to contain diesel/electric motors. This would treble the capacity of the motors in existing boats, provide faster surface and submerged speeds, and enable the boat to dive to greater depths. Two versions were being built, the Type XXI to replace the conventional ocean-going boats and the smaller Type XXIII for coastal operations. Production was in the hands of the Reich Minister for Armaments, Albert Speer, who had inaugurated a system of prefabricating sections in thirteen dispersed factories, capable of being transported along canals to final assembly lines. This reduced the man-hours utilised on building the conventional boats, and production was in full flow. Enigma decrypts revealed this programme to the Allies, who estimated that some of these new and dangerous U-boats would enter operational service in early 1945.
December brought the usual winter storms which reduced activities in the high seas, but the ocean-going U-boats sank nine merchant ships totalling about 58,500 tons in the month, from a total of almost 135,000 tons lost by the Allies. They lost thirteen of their own number, two of which were destroyed during a raid on Hamburg by the US Eighth Air Force.
Despite these unfavourable results for the U-boat Arm, there was some evidence in December that its commanders were becoming more adept at avoiding detection by the use of the schnorkel, which was by then fitted with a radar device for identifying the approach of aircraft. The Admiralty was also viewing the imminent appearance of the electro-boats with concern, aware from decrypts and air reconnaissance that numbers had been built, were working up to operational efficiency and would soon be sent on war cruises. On the last day of the year the US Eighth Air Force was diverted from its main task of destroying the German synthetic oil plants to an attack on the assembly yards at Hamburg, and the bombers succeeded in destroying two Type XXIs and badly damaging others.
Another worry for the Admiralty concerned the decrypts, for the U-boat Arm was making increasing use of the Sonderschlüsel (Special Key) system in which the Enigma keys were different for individual U-boats. Bletchley Park was unable to decrypt these and thus the departure times, locations and return times of some U-boats were not known to the Admiralty.
Despite these ominous developments on the high seas, by January 1945 the Wehrmacht faced an impossible military situation and the prospect of inevitable defeat. The centres of most German cities lay in ruins from concentrated air bombardment, the Luftwaffe had been reduced to a fraction of its former strength, Anglo-American armies had broken through the ‘Western Wall’ and were advancing into German territory, while great Russian armies had overrun East Prussia and were pouring through Poland towards Berlin itself. Yet it seems that Dönitz believed in miracles and was convinced that his new electro-boats could deal a decisive blow against the Western Allies.
The Kriegsmarine was also presented with an enormous operation in the Baltic in this period, for it had become necessary to begin evacuating civilians and military personnel from the eastern provinces, away from the advancing Russian forces. All available warships and merchant ships were pressed into service for this purpose, even including some U-boats. The pocket battleships Lützow and Admiral Scheer and the heavy cruiser Prinz Eugen attempted to cover this operation by bombarding the forward positions of the Red Army.
On the Western Front the first day of the New Year began with an attack by seventeen Seehunde Type XXVIIB midget submarines of K-Verband, which set out from Ijmuiden in the Netherlands to hunt for Allied shipping in the Outer Scheldt bound for Antwerp. This port had been captured by the British 11th Armoured Division on 4 September 1944. Its docks were almost undamaged and had become an important means of supply for the British and Canadian forces in the northern sector of operations. Dönitz had set great store on this operation, but he was to be disappointed. The two-man submarines succeeded in sinking one small trawler but only two returned to base. Some of those missing were destroyed by gunfire but others had run ashore and become stranded. Further attacks by small attack craft on shipping off the coasts of Kent and Belgium were completely unsuccessful. Their losses during the month amounted to ten Seehunde, ten Biber one-man submarines and seven Linsen motor boats.
The strength of the operational ocean-going U-boats in January stood at 144, with 260 more undergoing training and trials. These sank eleven merchant vessels amounting to about 58,000 tons during the month, from a total of 104,000 tons lost by the Allies. Mines accounted for much of the remainder. Fourteen U-boats were lost, with another raid on Hamburg by the US Eighth Air Force destroying three more Type XXIs and damaging nine others. These massive air attacks also caused huge damage to dock and assembly facilities, bringing the production of the electro-boats almost to a halt.
The small battle units of K-Verband fared somewhat better in February, sinking one tank landing ship and a cable ship, as well as damaging a tanker, but they lost four Seehunde and three Linsen, as well as six Molch or Biber one-man submarines. The month brought no improvement in the situation for the major U-boat Arm. A new coastal Type XXIII electro-boat which had sailed from Horten in Norway on 29 January attacked a convoy off Newcastle-on-Tyne, without success, and then returned to base. Another Type XXIII was lost in a collision in the Baltic. The U-boat Arm accounted for fifteen merchant vessels totalling about 65,000 tons, within an overall total of 110,000 tons lost by the Allies during the month, but it lost twenty-two of its ocean-going boats. The expected carnage from the new electro-boats had not occurred, owing primarily to delays in production and damage to the assembly facilities. The war was drawing to its inevitable close, with defeat for Germany.
During March U-boats sank thirteen merchant vessels totalling about 65,000 tons but suffered the enormous loss of thirty-two of their own number. Thirteen of these were destroyed by the US Eighth Air Force during concentrated raids on Wilhelmshaven, Bremen and Hamburg at the end of the month. These losses included only two Type XXI electro-boats and once again the assembly programme for these vessels was seriously impaired. The midget submarines and motor boats continued their suicide missions during the month, sinking three merchant vessels at the expense of huge losses. Nine Seehunde and twenty-seven Linsen were lost, as well as forty-two Biber or Molch. Fourteen of the Biber were destroyed by an accidental explosion while in harbour at Rotterdam.
April was the last full month of the war. By this time the newly trained crews with their ocean-going U-boats had built up numbers to as many as 166, with 263 others following behind within the system. The new arrivals joined in the fruitless task of overcoming an increasingly powerful enemy at sea. The U-boat Arm sank thirteen merchant vessels totalling almost 72,000 tons during the month, from an overall total of 104,500 tons lost by the Allies, but suffered its worst monthly losses of the entire war. No fewer than fifty-five ocean-going U-boats were destroyed, twenty of them as a result of massive air strikes by the US Eighth Air Force and RAF Bomber Command on Kiel and Hamburg. Others were sunk by cannon-firing de Havilland Mosquitos of RAF Coastal Command while en route from Germany to bases in Norway. The only Type XXI electro-boat to embark on a war cruise, U-2511, was scheduled to leave Bergen on 17 April but its departure was delayed by a damaged periscope and it encountered no enemy forces before being ordered to surrender. If this type had been available in earlier months, it could have had a profound influence on the course of the war at sea.
The small vessels of K-Verband also attempted to make an impact on the enemy in April, laying mines and making torpedo attacks. Two Seehunde sank one small tanker and a large merchant ship in waters off Dover, but the group lost twelve Seehunde, nine Biber and seventeen Linsen in the month, from attacks by aircraft and warships. The operations of this ill-starred group then came to an end.
With the Russian forces on the outskirts of Berlin, Hitler committed suicide on 30 April. The Deputy Führer was Reichsminister Herman Goering but Hitler had bypassed him and appointed his staunchest supporter, Grossadmiral Karl Dönitz, as his successor. It was evident to Dönitz that the military situation had become completely hopeless and that he should capitulate immediately, but he delayed for a few days to complete, so far as possible, the evacuation of troops and civilians from the eastern provinces. On 4 May he advised U-boat commanders that they were to scuttle or destroy their boats on receipt of the codeword ‘Regenbogen’. Meanwhile, he appointed Generaladmiral Hans von Friedeburg to take his place as commander-in-chief of the Kriegsmarine and also authorised him to surrender to Field Marshal Sir Bernard Montgomery at his headquarters on Luneburg Heath. The proposal to scuttle U-boats was not authorised by the Allies and could not be implemented. Instead, all U-boat commanders were ordered to fly black surrender flags and begin their journeys home. The surrender became effective at one minute past midnight on 8 May but the terms were transmitted to all German forces, including U-boats at sea, during 4 May.
Not all U-boat commanders received the messages immediately and some engagements took place. In the first seven days of the month twenty-eight more U-boats were sunk, primarily from air attack in the areas of Kiel Bay and the Kattegat, while U-boats sank three merchant vessels totalling about 10,000 tons. It is estimated that by the end of the war the Kriegsmarine had evacuated about two million troops and civilians via the Baltic, of whom about 20,000 were lost at sea, in what must be regarded as its biggest operation of the war.
The Allies lost approximately 21.5 million gross tons of merchant shipping from all causes during the war, although their massive rebuilding programme produced over 45 million gross tons during this period. It is calculated that U-boats sank 2,927 merchant vessels amounting to almost 15 million gross tons of the total lost, as well as 175 Allied warships totalling about 243,000 tons. The records also show that 1,110 ocean-going U-boats were dispatched on war cruises. Almost 800 of these were destroyed at sea, from air bombardment in docks, or from causes which cannot be determined. The U-boat Arm came close to winning the Battle of the Atlantic during 1942 but was defeated by Allied skill, determination and improved weaponry, with the decryption of Enigma signals playing a major part in the conflict.