Chapter XI
The U-boat and the Allied Invasion of France

  1. Existing U-boat fleet was not well suited for defensive mission and could not offer effective resistance.

  2. Pre-invasion scrutiny of traffic.

  3. U-boat reaction to an invasion scare of 29 January 1944.

  4. Preparation by U-boat navy for invasion.

  5. German intelligence and evaluation of the invasion, both before and after 6 June.

  6. Disposition of U-boats, D-Day to D-Day plus 2.

  7. U-boat attack could not get underway against superior Allied defense.

  8. Breakdown of German land communications.

  9. Increasing difficulties: preparations for withdrawal, June - July 1944.

  10. Retreat to southern Biscay ports, early August 1944.

  11. Operation in the Channel ends, 26 August.

  12. Destruction of Bordeaux, 26 August.

  13. Withdrawal to Norway.

  14. Conclusions of the invasion period. The U-boat fleet ready to resume the naval offensive from Norway and Baltic.


  1. Existing U-boat fleet was not well suited for defensive mission and could not offer effective resistance.

    In keeping with his conception of the U-boat as an offensive weapon Admiral Dönitz had so concentrated his efforts on convoy warfare in the open sea that by mid-1943 his fleet was composed solely of ocean going operational types:

    500 ton class, for convoy operations in the North Atlantic. Principle strength of the fleet.

    740 ton class, for Middle Atlantic and Caribbean operations.

    1200 ton class, for South Atlantic and Indian Ocean operations.

    The 240 ton class had been driven from the British coastal waters early in the war and had been discontinued. With the crisis of the summer, 1943, it became clear that a new type submarine was necessary. Plans included a small type (XXIII, 228 tons) and a large type (XXI, 1600 tons), both capable of high underwater speed. The omission of a 500 ton type aroused speculation as to possible future abandonment of mid-ocean convoy battle and a return to coastal ambush or attacks on convoy meeting points. Meanwhile, however, the 500 ton U-boat did not yield the open sea without a struggle and every effort was made to improve the existing fleet for North Atlantic operations long after they had cease to pay. This persistence was no doubt natural in view of the strategic justification for the U-boats existence.

    Considerations of invasion defense, which became evident early in 1944, seems to have been corollary rather than primary in U-boat Command's planning. The new types did not presage any change in strategy, but merely an adjustment of means to the one end of destroying the enemy's sea transport. The new type of small submarine, designed for a resumption of U -boat operations in European coastal waters, or even experienced 500 ton schnorchelers might have proved formidable defensive weapons. But the invasion came too soon.


    The U-boat branch had not effected its basic readjustment to a problem long recognized as acute. Command was forced to commit his fleet of outmoded 500 tonners, hastily equipped with schnorchel, in a battle for which they had not been intended and from which they might hope for honor but not victory. The U-boat was not in the Channel on D-Day and once there proved powerless to impede the flow of ships. By the end of August the attempt was abandoned and all energies turned to saving the U-boats still afloat in French waters. With skill and tenacity the crippled fleet was withdrawn in good order to Norway and Baltic ports. Morale was maintained and the one end of resuming the naval offensive was not for a moment lost from view.

  1. Pre-invasion, scrutiny of traffic.

    The invasion of North Africa had found the U-boat wanting, but in this case the German navy had been taken by surprise.1 Before the invasion of western Europe close watch was kept on the following:

    1. Any indication in U-boat traffic of U-boat preparations and counterplans.

    2. Any suggestions in traffic that Germans might have detailed knowledge of Allied plans.

    In connection with the second point above, the reading of Japanese Naval Attaché traffic was helpful, despite the lack of assurance that the Japanese would be fully informed of German intelligence on so vital a matter as the invasion of western Europe. Along with many conflicting rumors and predictions as to when and how the invasion would take place, the Japanese Naval Attaché did furnish valuable and timely information on the organization and disposition of German coastal defenses. This was first hand, for the Germans gave the Japanese a tour of fortress Atlantic in May.


  1. U-boat reaction to an invasion scare of 29 January 1944.

    As early as January 1944 U-boat traffic gave clear indication that the U-boat would be used in a major attempt to prevent landings on the European coast - whether properly equipped for this task or not. According to a "very trustworthy agent" in England, the end of January was the earliest possible time at which an invasion could be attempted. In the early morning hours of 29 January a neutral tuna fishing fleet of 18 vessels in the Bay of Biscay was reported by German aircraft as 200 to 300 landing craft. The alarm continued for eight to nine hours. Orders issued during this time were marked by a sweeping disregard of ordinary caution. The 22 U-boats patrolling the western approaches were told to ignore their greatest enemy, Allied aircraft, and to cruise for Biscay at maximum speed on the surface. Outbound and inbound U-boats were equally affected. It is interesting to note that this false invasion caused more drastic measures to be taken by U-boats than were immediately evidenced on 6 June.

  2. Preparation by U-boat navy for invasion.

    In addition to the evidence of counter invasion intentions furnished by the scare of January, the following U-boat activities were appreciated in their bearing on the coming crisis.

    1. Weather reporting.

      Beginning on 31 December, 1943, with the assignment of weather reporting areas to three U-boats in the central North Atlantic, U-boat Command maintained U-boat weather stations in the North Atlantic throughout the following months. Although U-boats in the past had been given special weather reporting tasks, this function had hitherto been subordinated to U-boat operational ends or to blockade running. The function of the 1944 weather U-boats, however, was clearly subordinated to the defensive plans of the Wehrmacht as a whole. During the period from 1 January to 18 May, 1944, 29 U-boats worked as weather stations. Of this number only two


      were sunk (See SA 30/D-2, 18 May 1944)2 The urgency attached to these U-boat weather transmissions was shown many times in Command's instructions and reprimands to the boats. On 4 May weather boats were told:

      "Reports are of the utmost importance for the entire conduct of the war - judgment as to air situation, invasion, etc." (1416/4 May 1944)

      Again on 10 May:

      "Omission of weather reports is of great disadvantage to whole waging of the war." (1242/10 May 1944)

      Among the first messages sent after the invasion began was an order to four U-boats in the mid-Atlantic, not regular weather reporters, to "send a supplementary weather report today. Urgently needed."

    1. Assembly of 500 tonners in Biscay.

      In March it was noted that 500 tonners were being recalled to French ports. At the same time new 500 tonners were again being released from the North after a lull in January and February but were being sent straight to Biscay without any intermediate operation. During the last half of May no 500 ton U-boats left French ports, with the exception of few schnorchel U-boats (Group Dragoner) and they were recalled from the Channel on 25 May. On D-Day there were 61 U-boats in Biscay ports of which 49 were 500 tonners. If the figure 61 seems small, one needs to be reminded that the total Atlantic operational fleet had not exceeded 100 U-boats (approximately) for some months prior to the invasion. Additions to the fleet from the North in April and May were offset by current losses in the Atlantic. The significant changes in the Atlantic fleet had been the decline in the number of U-boats at sea. Between 31 March and 6 June the ratio of U-boats at sea to U-boats in Biscay ports had changed from approximately 6:4 to 4:6.


    1. Schnorchel and Group Dragoner.

      It is not suggested that schnorchel was developed solely with the invasion in mind, but the possibility of using schnorchel fitted 500 tonners in the Channel was obvious. The imminence of the invasion had emphasized top priority of schnorchel production and installation. From 20-25 May a few schnorchel U-boats were put in the Channel between Brest and Cherbourg, apparently as a test of the new device in enemy coastal waters. Called Group Dragoner (though not more than three U-boats seem to have operated at anyone time) they received orders to surface and submerge upon changes in the enemy situation. Enemy sightings were regularly reported to the group on a special circuit. In 0118/25 May, Command concluded that schnorchel was being located by Allied aircraft. At 1232/25 May the group was signaled, "Because of enemy situation, which at the moment promises no further success, all Dragoner U-boats return to Brest." No "success" is known that could have been achieved by these tentative operations.

  1. German intelligence and evaluation of the invasion, both before and after 6 June.

    Available evidence from all traffic seen here strongly suggests that the Germans were unable to formulate any clear and detailed idea of Allied intentions. They may have known beyond much question that the invasion was coming but exactly where and when it would strike was apparently revealed only after the fact. Information from Japanese Naval Attaché traffic, then being read with a lag of two to three days, tends to confirm German uncertainty not only during the preinvasion period but also during the critical period between the landing in Normandy and the break through at Avranches in August. (All of the Japanese Naval Attaché traffic was, of course, made available to the Army.)

    1. Up to D-Day.

      As early as 17 April Admiral Dönitz proclaimed to the navy that Allied preparations were complete and that invasion was imminent. " ... this invasion will be decisive for the issue of the war, and for the existence of the German people." The navy


      was to attack... "without thought for the preservation of the ship, without hesitation against even the most unfavorable odds." The German air force thought 26 April the invasion date. As May approached naval surface units were increasingly engaged in channel mine laying, using such cover names as Schranke (barrier). The locations of German minefields were of course made available by German traffic. On 8 May Luftflotte 3 deduced from Allied aerial behavior that " . . . landing is planned in the area Harve-Cherbourg," an appreciation which Luftflotte 3 had".. . already often expressed." (Sunset 557, 11 May 1944)3 Yet on 27 May, Luftflotte 3 regarded the Dieppe-Seine Bay area as the probable landing target. (Sunset 576, 30 May 1944) Hitler's own version of Allied plans, as interpreted by Ambassador Oshima on 28 May after an interview with the Führer, is perhaps the most interesting of the conflicting rumors and predictions which were picked up in German circles and relayed to Tokyo in Japanese Attaché and diplomatic traffic. The Führer expected:

      1st: Diversionary actions against Norway, Denmark, Southern Biscay, French Mediterranean, etc.

      2nd: Bridgeheads on Normandy and Brittany as "tests."

      3rd: All-out second front in the area of Straits of Dover. (Japanese Diplomatic #511, 28 May 1944)

      Hitler expressed a limited willingness to wait. "I will give them two or three months more time, but if they don't come then, Germany will take the offensive" (i.e. against Russia). The source of Hitler's appreciation of Allied intentions is not known but there is evidence that German High Command continued to share his impressions.


    1. From D-Day to August.

      The Germans undoubtedly tried to prepare for any eventuality. It is known from traffic that the navy had taken special precautions in anticipation of a northern thrust via the North Sea. Group Mitte U-boats, mostly drawn from the Baltic, had been standing guard off southern Norway and were receiving on the same radio circuit (Coastal) which served U-boats in the Biscay area. The organization of U-boat Group Mitte under a separate command, COMSUBs Mitte, had been perfected for many months under the catchword Wallenstein. In addition to Group Dragoner, U-boats in Biscay ports were apparently waiting to sail against invasion armadas under the catchword Landwirt.

      The sequence of events of early 6 June as they affected U-boats is known only for Group Mitte, since these U-boats were at sea and they as well as U-boat authorities in Norway were reached by radio. No special significance may be attached to the fact that the Norwegian authorities and Group Mitte were alerted first (at 0343B/6) according to traffic read here: "Immediate readiness. Indications for beginning of invasion." The omission of "on Channel coasts," added at 0410B/6, may have been an oversight on the part of an excited drafter. At the same time it was clear that the possibility of a Norwegian landing could not be disregarded, for fifteen hours after all U-boats at sea had been informed of "Enemy landing Bay of the Seine," Group Mitte submarines were ordered to "report immediately all enemy movements which give evidence of landing intentions and take full offensive action at the same time." (1821B/6)

      It was appreciated at 1832B/6 that the landing between Le Havre and Barfleur was a "major operation," but U-boat Command could not concentrate his forces against it for fear of landings elsewhere. "No tangible data" were at hand concerning Allied objectives: "we must expect surprise attacks, and covering fairly extensive areas too." (1832B/6) The majority of the U-boats that put to sea from France on 6 June went to positions in Biscay and not into the Channel. Early on 9 June waiting areas for Biscay U-boats were shifted so that " the event of enemy landings in Biscay, (U-boats) can get to landing area faster." (O250B/9) A few minutes later it was announced that "The main attack area of the English-American invasion has continued to be the Bay of the Seine triangle


      between Cherbourg and Le Harve." (0301B/9) Not until 12 June were non-schnorchel Biscay U-boats (21) ordered back in port, and they were withdrawn because of the Allied antisubmarine activity.

      The Mediterranean area was likewise a realm for fear. On 8 June OKW (Armed Forces High Command) brought southern naval authorities to the "very highest degree of alertness," since there were "clear indications of imminent operation in the Eastern Mediterranean" against which U-boats would be put into action. (0447/8 MED) If U-boat traffic ceased to reflect any major uncertainties after 12 June, it was perhaps due to a local situation which was so, far out of hand as to discourage further speculation afield. Yet the uncertainty was apparently not removed. On 30 June the Navy (non-U-boat) ordered increased vigilance for landings in the eastern part of the Channel, and on the coast of Flanders. (Sunset 611, 2 July 1944) If one may believe the reports to Tokyo from Japanese representatives in Berlin, the Wehrmacht could not muster an all-out counter offensive against Normandy because throughout June and July it anticipated a landing by "Patton's army" in the Dieppe-Calais area.4 (References Japanese Diplomatic #607, 19 June; #626, 24 June; #693, 13 July; Japanese Naval Attaché #110, 20 June; #199, 10 July; #239, 18 July; #249, 24 July) On 2 August, when the American army had penetrated to Avranches, German Command was still worried about the landing target for Patton's Army. (Japanese Diplomatic #781)

  1. Disposition of U-boats, D-Day to D-Day plus 2.

    1. U-boats in the invasion area.

      Within 48 hours after the first landings on Normandy 36 U-boats (500 tonners) left French ports, 30 of them to patrol Biscay approaches and six (schnorchel boats) to attack invasion convoys in the Channel. Of U-boats off southern Norway, six (Group Mitte) were ordered to remain in waiting areas about 30 miles from the Norwegian coast and to report all enemy movements that would indicate landing intentions. (0351B, 1821B, 1828B/6) One was ordered to a station off Malin Head


      and another to the Minch. Four schnorchel U-boats on cruise out from the north were to "...head for western France at highest maintainable speed. Proceed submerged during the day, heed ordered precautionary measures." (0532B/6) By 8 June the only two type VIId minelayers, U-214 and U-218, were ordered to carry out minelaying along the invasion lane. (0522B/8)

    1. U-boats in distant areas.

      These submarines were not immediately affected by the invasion. These included the usual three weather reporters in the north central Atlantic, the customary sprinkling of independents off Nova Scotia, in the Caribbean, and along the Gold Coast, and three in the North Atlantic proceeding to the Indian Ocean. The Japanese I-52 was in the South Atlantic, headed for Biscay. U-530 (Lange) was outbound from France to rendezvous with the I-52 before operating off Trinidad.

  1. U-boat attack could not get underway against superior Allied defense.

    Less than half of the available U-boats were schnorchel equipped and these had been divided between Biscay and the Channel. But with or without schnorchel if the U-boat succeeded in getting out to sea, once there it was practically immobilized. Reports from U-boats consisted largely of a series of short signals telling where and when they had been attacked by aircraft. For example, on 7 June Boddenberg (U-963) reported three attacks in less than two hours. (OI37B, 0223B, 0325B/7) On 11 June it was announced that the schnorchel U-boats, which were supposed to operate as far east as Cape Barfleur, were"...proceeding very slowly because of enemy interference" and were still west of the Cherbourg peninsula. (1150B/11 Gray) Messages to U-boats made up a series of exhortations to attack offset by warnings on the Allied defense situation. An earlier attempt was made to strengthen the Channel group by shifting boats from the Biscay patrol, but the inadequacy of the U-boat for its task tended to confine plans to paper work and dispatches. On 10 June non-schnorchel U-boats were expressly forbidden to engage in Channel operations and on 12 June even Biscay U-boats without schnorchel were ordered back into port (approximately 21


    submarines), there to be fitted as rapidly as possible. The Holzbein (wooden leg) series of messages to schnorchel U-boats entering the Channel summarized the sacrifice as follows:

    ". . . the U-boat which inflicts losses on the enemy during his landing has fulfilled its supreme task and has justified its existence, even if it accomplishes nothing more." (2337/11 June 1944)

    But this stirring bit of moral philosophy assumed that the U-boat could penetrate to the landing area.

  1. Breakdown of German land communications.

    On 8 June (1547/8 Orange 1) COMSUBs West's communications officer (at Angers) informed U-boat Command by emergency radio circuit that all landline communications with Berlin, Kiel, Wilhelmshaven, Paris, Brest, Aix, La Rochelle were out of order due to enemy action. One line to Paris was in limited working condition, and by the 10th of June it was gone too. With this wholesale breakdown of landline communications emergency radio circuits (Gray 6 and Orange 1) were put into operation for traffic between COMSUBs, flotillas, and other shore authorities. As a result, traffic to be processed by the Atlantic Section fully tripled in volume. The inner workings of the administrative, supply, and command structures of the U-boat navy were opened for direct and current inspection. It became possible to follow U-boat operational orders, reports, controversies, confusion, and troubles of all sorts from one end of the naval hierarchy to the other and back again.

  2. Increasing difficulties: preparations for withdrawal, June - July 1944.

    By the end of June, 12 U-boats had been sunk - with very little to show for their sacrifice. The anticipated withdrawal to Norway began to show in orders to eight U-boats in the Atlantic that they should leave their operational areas with sufficient fuel to reach Bergen. (2312B/12 June) The Channel operation continued - rather the attempt to operate, for the greatest difficulty lay in actually reaching the landing areas. Commander's were ordered to make unconditional effort to


    reach the area north of the Seine Bay, where ". . . prospects of success are the greatest and most effective for easing the land situation." (1824/19) In addition to the problem of getting into offensive position at sea, formidable for relatively inexperienced Commander's worried with constant enemy defense above the water and with schnorchel and Channel navigation underwater, problems ashore multiplied until the major concern of the Navy was to hold itself together. It should be remarked, however, that despite the difficulty of meeting the demands of the moment, plans for the future resumption of the naval offensive were being carried out. Late in June the officers and crews of five old 500 tonners (type VII c), were to leave France for Germany to commission new type XXI U-boats in the Baltic. (1459/24 Gray)

      Problems of supply and administration.

    1. More suitable bases for Channel operations.

      To eliminate the necessity of rounding Breton and Normandy peninsulas before being able to operate, an unsuccessful attempt was made to utilize Le Harve, Boulogne, and the Channel Islands as emergency U-boat ports. The U-boats could not reach these ports with ease and the Navy could not equip the ports with necessary U-boat supplies.

    2. Supply and transportation.

      As the northern Biscay U-boat bases (Brest, Nazaire, and Lorient) were cut off from inland communications, U-boats from Bordeaux had to assume tasks of supply. At one point U-boats were also carrying ammunition to besieged Cherbourg and St. Malo. These tasks had to be abandoned with the rapid deterioration of the land situation. Meanwhile, the complete disruption of transportation systems from Germany to Paris and from Paris to Biscay ports turned the shipment of supplies and the transfer of personnel into a matter for frenzy. The shore organization was paralyzed or reduced to chaos. Yet there was little evidence of hysteria, although an abundance of temper and harsh words over such things as trucks requisitioned by one command and stolen by another.


    1. Schnorchel operations.

      No one problem illustrated the naval crisis in its entirety more completely than did that of schnorchel installation. Every command was involved and countless messages went back and forth probing, querying, demanding, protesting, and reporting every aspect of schnorchel and its installation from parts lost enroute to last minute adjustments and breakdowns onboard. Everything possible was subordinated to the task of installation. The date of schnorchel completion for an individual boat was practically its war readiness date. Disagreements between dockyard officials and operational commands were aired vigorously. On 11 July COMSUBs West informed Commanding Admiral U-boats (Admiral von Friedeburg at Kiel, in charge of U-boat administration) that "Stubborn attitude of construction committee with respect to Front demands is intolerable in the present situation." (1802/11 Gray) Even the installation of a compressed air toilet on a schnorchel submarine could become a major problem between commands. The 9th U-Flotilla complained to COMSUBs West that the dockyards "pig-headed refusal" to go ahead with the installation without a directive from Naval High Command was causing ill will. (2020/7 July Orange)

    2. The attempt on Hitler's life - 20 July 1944.

      By the 20th of July, Admiral Dönitz was primarily concerned with the U-boat navy's chances of returning to fight another day. The collapse of the entire command structure which threatened with the execution of the assassination plot was successfully met by swift action and decrees from Dönitz himself.

  1. Retreat to southern Biscay ports, early August 1944.

    Quite apart from the military necessity for denying use of the use of the ports to the Allies, the holding of Brest, Nazaire and Lorient was essential for the immediate safety and future effectiveness of the U-boat arm through operational prospects in the Channel area were negligible. The bulk of the U-boat fleet had been based on Brittany. To save the remaining U-boats it was of the utmost importance to equip them with schnorchel before they should abandon the U-boat pens.


    Hence, as the Allied armies closed in on the Brittany ports, Admiral Dönitz ordered "by direction of the Führer" that U-boat repairs especially schnorchel installation were to be carried out despite the presence of Allied armies at the fortress gates. (1127B/8 August) U-boats at sea were given Bordeaux and La Pallice as homing ports but were cautioned to keep their fuel supply adequate for a return to Norway should the situation in France require an order to that effect. As U-boats were made ready for sea, those with experienced crews were still sent into the Channel, prepared to make Norway, while others were assigned the task of transporting essential personnel, fuel, torpedoes, and Zaunkönig testing units to the south. The remaining U-boat personnel with one Flotilla Commander were to join the naval shore units and army in resisting to the end. By 8 August COMSUBs West (Captain Rösing) had moved from Angers to La Rochelle.

  1. Operation in the Channel ends, 26 August.

    During the counter invasion operations COMSUBs West had assumed control of Channel U-boats a control carried out in close consultation with Naval Group Command West (Admiral Krancke in Paris) and with Commander U-boats in Germany. To free COMSUBs West for the task of salvage, U-boat Command took over operational command on 14 August. On the 15th Channel U-boats were ordered to head for Norway after completing their missions. Ever mindful of morale and of the U-boat offensive, even when a full retreat was under way, Dönitz signaled his few front boats on 21 August as follows:

    "In the stern battle against the enemy storming us from the west you are in the foremost line now as before. . . . your full operation is necessary to relieve the land front. . . . you can do it with a single torpedo hit. . .  But I know that you, my U-boat warriors, carried on by the old spirit of attack think only of destroying the enemy. Be assured that I follow your battle continually and that you are always in my thoughts." (1914B/21 August 1944)

    On 26 August came the official order to send no more U-boats into the landing area. U-boats were henceforth to be equipped for operations in English coastal waters. (1757B/26)


  1. Destruction of Bordeaux, 26 August.

    Any plans the Germans may have had to support the U-boat fleet even temporarily by means of Bordeaux became untenable with the Allied invasion of the French Riviera on 15 August. On 17 August seaworthy V-boats at Bordeaux were ordered to be ready for sailing at a moment's notice while continuing the task of loading equipment. U-boats under repair were put on 24 hours readiness. The Führer gave unconditional orders that the port be held until the installation of the last schnorchel was completed. The estimate of 5 September for this work was too long. Work was rushed. The last U-boat to leave sailed on the 25th. Three 1200 tonners had to be blown up, but three others succeeded in clearing for the Far East with part of the cargo stored in Bordeaux for Japan and Penang. On the 26th all military installations of the U-boat base together with confidential and cipher material were destroyed and the harbor rendered useless. Naval personnel remaining were divided between the Gironde fortress.

  2. Withdrawal to Norway.

    The crisis which destroyed Bordeaux on the 26th was communicated on the same day to the remaining U-boat bases in a dispatch from Admiral Dönitz:

    "the military situation has made it necessary to prepare all U-boats at bases as quickly as possible for combat operation or transfer to Norway. This task has so far been mastered very well by the Flotillas and dockyards and will surely be completed. The U-boat war will continue with the old spirit and new measures. I have therefore ordered that as many U-boat personnel as possible, including COMSUBs West, return to Germany by land or sea in order that they may be used in continuing the U-boat war. The task of those attached to Flotillas who are left behind is to defend the bases to the last man and the last cartridge, under command of the senior Flotilla chief and in cooperation with other soldiers of all branches of the Wehrmacht, risking all with the steadfast heart of the front U-boat warriors; thus to deprive the enemy of the harbors as long as possible. I


    am certain that this task, necessary for the defense of the Fatherland will also be completely fulfilled. It goes without saying that I am with you wholeheartedly day and night." (1934B/26 August 1944)

    At 0300B the following morning the office of COMSUBs West ceased. Before leaving for Germany, Captain Rösing took "leave of the troops to whom all my thoughts belong" in full confidence that they would do their duty as before. U-boats at sea which were forced back after Bordeaux had been discontinued could still find a haven in the pens at Pallice or Nazaire. While the RAF worried the Germans with a special monster of a bomb, designed for these pens among other things, no U-boat inside was seriously damaged, despite direct hits which scattered considerable reinforced concrete through the interior of the pens. Reaching the pens was a different matter. Allied antisubmarine measures were too severe for the maintenance of any escort system. By the 1st of September U-boats were forbidden to attempt entry to Pallice. Departures from the pens were kept extremely secret in an effort to get the U-boat out and under the water before attracting attention. U-boats headed for Norway received an average of 55 cubic meters of fuel and 31 days provisions, together with a warning that antisubmarine operations would naturally shift from Biscay to the Norwegian approaches. The last U-boat left Brest on the 3rd of September, Lorient on the 9th, Pallice on the 10th, and Nazaire on the 23rd. (one U-boat, U-255, was held at Nazaire until certain parts could be flown or brought by sea from Germany. In May 1945 Commander Piening delivered the U-255 to the British.)

  1. Conclusions of the invasion period. The U-boat fleet ready to resume the naval offensive from Norway and Baltic.

    Before the last U-boat sailed from France, COMSUBs West had completed his reorganization and had established himself at Bergen, (18th September), where he awaited his flotillas returning from their three year stay in France. In November, the transfer operation was regarded as completed and it was announced to all that of the 35 U-boats that had attempted the passage from France to Norway only four had failed to make


    port in Norway or Germany. On the whole the counter invasion effort had exacted an extremely high price. Of 48 U-boats that attempted Channel operations during June, July and August, 23 were sunk And, yet, despite the high losses, the meager successes, the desperate circumstances both in France and in Germany, the U-boat organization did not forget its end. Throughout this trying period the future policy was being shaped. The last straggler from Biscay had hardly reached Norway before U-boat Command was issuing full orders for the "Total Underwater Warfare" already beginning in British coastal waters.


Table 1
The U-boat and the Allied Invasion of France

  No. Sunk Out of
Far East
Left in
U-boats in French Ports on D-day              
500 tonners 49 25 1 22 -- 1  
Larger types 12 2 3 5 2 --  
Total 61 27 4 27 2 1 61
U-boats entering invasion area after D-day              
Enroute on D-Day
Returning from Atlantic
7 1 2 4      
Outbound from Norway 4 3 -- 11      
Japanese I-52 1 1 -- --      
Total 12 5 2 5     12
Enroute after D-Day from Norway 13 11 -- 12      
Returning from Atlantic 9 4 -- 5      
Total 22 15 -- 7     22

Total U-boats involved 95 247 6 339 2 1 95

1 One U-boat put back into Norwegian port after starting out for invasion area.
2 Includes U-boats sunk outside of invasion area.
3 Includes six large U-boats which left France after D-Day for operations in distant areas and which returned safely to Norway.


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1. This statement is confirmed by November 1942 U-boat traffic, which was read in December 1942.

2. For these reports see: Records of the National Security Agency, U.S. Navy, OP-20-GI, "Special Studies Relating to U-boat Activities, 1943-1945," SRMN-054, National Archives, Washington, D.C., Record Group 457.

3. Sunset reports were daily intelligence summaries provided by the British War Office and Air Ministry from intercepted message traffic. See: Records of the National Security Agency, European Theater of Operations, "'Sunset' Daily Intelligence Reports," SRS-1869 (Parts 1-7), National Archives, Washington, D.C., Record Group 457.

4. This is in reference to the deception plan for an Allied landing in this area.

Transcribed and formatted for HTML by Chuck Roberts for the HyperWar Foundation