Chapter V
The U-boat Fleet and New Schnorchel

  1. The Allied invasion of France.

  2. The German Navy never lost sight of its one end: Renewal of the offensive at sea.

  3. The fleet of new submarines did not sail.

  4. The schnorchel fleet.

    1. Starting the U-boat war all over again.

    2. Old and new problems.

    3. Weaknesses not corrected.

  5. Surrender.


Type VIIc U-boat


The New U-Boat Fleet and the Schnorchel

Late in determining the need for a radical change in the Fleet, the German Navy had lost time never to be made up. The issue was to be decided by circumstances beyond its control. As the German land situation went to pieces, the Navy worked with steady and undaunted determination to complete the new types, but was forced into postponement after postponement. To the one end of resuming the offensive at sea, everything was subordinated. In lieu of the fleet of new types, every available old type was fitted with schnorchel. The schnorchel fleet did well. It increased in size despite losses and increased its pressure against Allied shipping--to the very day when forced to surrender because there was no longer a Germany to defend.
  1. The Allied invasion of France.

    The Allied invasion of France on 6 June 1944 confirmed the past failure of the U-boat. The men and materials that had not been stopped in the Atlantic were landed on the coast of France, depriving the U-boat of its best Atlantic bases and beginning the internal collapse that was to cut the U-boat navy off at its roots. Having refused for so long to yield the Atlantic, the U-boat navy was not prepared for an eleventh-hour stand off the invasion beaches. It could not hope to succeed with outmoded weapon in its last attempt to prevent invasion--under conditions the most unfavorable ever yet encountered. Along with the concentration of Allied antisubmarine defense in coastal waters, the Allies were benefitting from the most complete decryption intelligence of the U-boat in the entire course of the war, for the sabotage of landline communications forced all naval administrative and high command traffic into emergency radio channels--and into Allied translations. The Allies knew the war-readiness date for every U-boat as well as its operational orders days before the U-boat sailed. These orders had to be carried out in shallow water operational areas for which the 500-ton U-boat had not been built. Although hastily equipped with schnorchel, these Channel U-boats lacked experience with their new device and were helpless. Two-thirds of the U-boats that attempted to operate against the invasion armadas were lost. In return for this sacrifice U-boats were told that insofar as they inflicted any damage at all on the


    landing craft they had fulfilled "their supreme task," had "justified their existence."

  1. The German Navy never lost sight of its one end: Renewal of the offensive at sea.

    It is remarkable that throughout this period of great trial and confusion and throughout the worse months to come, the U-boat navy did not lose sight of its one end: the renewal of the U-boat war in the Atlantic. While the Grand Admiral repeatedly addressed his men at sea with stirring promises of the future, the navy ashore subordinated everything possible to the installation of schnorchel and to the mass-production of the new types. Morale and discipline were maintained and the U-boat navy fell back to Norway and the Baltic in good order.

    From there, no time was lost in undertaking once more the blockade of Britain.

  2. The fleet of new submarines did not sail.

    The new U-boat navy of high underwater speed submarines, from which so much was expected, was not to sail. Admiral Dönitz had apparently planned to release types XXI and XXIII in large numbers during the fall and winter of 1944.

    They were to strike en masse, throw the Allies into confusion, and thus hold the land fronts where they were until German counterattacks on land and in the air could restore the military balance. Throughout the last winter of the war, the Allies watched the threat anxiously through the Japanese Naval Attache and Baltic U-boat traffic. The mass-production systems had been decentralized, but the destruction of German land transportation and the aerial bombardment of assembly yards were effective. The new types did not reach military strength, month by month postponement was reported by the Japanese Naval Attache--until the Allied land offensive reached the Baltic and North Sea ports. A few type XXIII submarines made cruises against England, but the only type XXI to sail was still outbound on the day of surrender. It appears that a further attempt was underway to achieve the goal of a true underwater craft. As has been stated, the types XXI and XXIII were dependent on schnorchel. Other than a burst of high underwater speed they did not offer


    the desired radical solution to the U-boat problem. In the course of the winter, the Japanese Naval Attaché reported details of still another new type, type XXVI, which was to add turbine propulsion to both diesel and electric. The turbine would give the U-boat endurance in underwater cruising at high speeds.

  1. The schnorchel fleet.

    Even without the new types, the German Navy made a strong recovery with the schnorchel-fitted older types. Unquestionably the most successful German counter-device, schnorchel, came too late to alter the course of the war but did enable the existing U-boat fleet to renew its menace. It was sufficiently successful to warrant being called the remodeler of the fleet. The U-boat was still bound to the water's surface, but the area exposed had been reduced to a minimum, and even this minimum could be camouflaged. It was a half-way revolution in submarine warfare, a difference in degree but not in kind, a stage in transformation of the U-boat into something like a true underwater cruiser. Economical and relatively simple, it made possible the salvage of all existing older operational types. In face of hopeless conditions in Germany, schnorchel enabled the U-boat navy to undertake what it called "total underwater warfare." The one positive contribution of the Allied invasion of France to the U-boat navy was the speed with which it forced Germans to complete their experiments at sea and equip all standard types with schnorchel.

    1. Starting the U-boat war all over again.

      It is sufficient evidence of the skill and pertinacity of the German Navy that the schnorchel started the U-boat war all over again. Deprived of French bases, the schnorchel fleet sailed from Norway and the Baltic to take what had been abandoned years before, a close-in blockade of the British Isles. Cruising submerged for as long as 70 days and finding bottoming tactics in shallow water highly favorable to their defense, U-boats entered the channels and inland seas of Great Britain, where they increased in numbers and in effectiveness to the day when they were ordered to cease.

      Nor did U-boats neglect distant areas and the open sea. More U-boats were off the U.S. and Canadian coasts in the


      weeks of the war than had been there at anyone time for the past 2-1/2 years.

      An attempt was made to resurrect group warfare against major convoys in mid-Atlantic with U-boats own passage to our coasts. It was characteristic of the U-boats general plight, however, that U.S. Navy forces, acting on decryption intelligence, went out to meet these U-boats and attacked them all the way in. Even with the advantage of decryption intelligence as to the U-boats whereabouts, it was difficult matter to home attacking craft onto a schnorchel U-boat that was in good working condition and that was handled by a Commander who had mastered his more complicated weapon.

    1. Old and new problems.

      It is further indication of schnorchel's significance that U-boat Commanders had to relearn the U-boats functions and Allied antisubmarine forces to relearn the U-boats habits. Every phase of the U-boats life was affected.

      U-boat seeing and hearing: Schnorchel cruising blinded and deafened the U-boat. At the same time it made the U-boat more dependent than ever upon periscope and hydrophones. It was necessary to interrupt schnorcheling, for frequent periscope and hydrophone sweeps.

      GSR: Since the schnorchel head could be located by radar, it had to be fitted with a permanent GSR aerial for warning purposes. A permanent aerial (round dipole) for meter wavelength radar was available, but not for centimeter radar.

      Communications: Reception on very low frequency at submerged depths had long been part of regular procedure. It was transmission which constituted a continuing weakness for the schnorchel U-boat. Transmission over the schnorchel "round dipole" was tried without success. To communicate with Control the schnorchel U-boat had to surface. Dampness from long submerged cruising tended to short the radio equipment. As the off-frequency procedure was enlarged, the future


      protection against D/F and interception was being developed in "Kurier" flash transmission.

      Underwater navigation: "Avoid surfacing for astronomical fix" became a new rule to whose observance U-boat Command devoted much attention. In addition to Elektrasonne beacons, U-boats charted their progress by soundings and sonar together with painstaking dead-reckoning and an accurate knowledge of currents and of their own speeds at the various screw revolutions.

    1. Weaknesses not corrected. Schnorchel had, in part, restored the U-boat its source of strength, its invisibility in the combat area. The U-boat was thus more difficult to locate before attack even though if area was known from decryption intelligence. Certain weaknesses mentioned in the U-boat Commander's Handbook of 1942, however, remained: low speed, limited lookout, and vulnerability.

  1. Surrender.

    The German U-boat navy alone remained when the Wehrmacht disappeared in ruins. It is important to remember that on V-E Day the German U-boat navy was still a dangerous combat unit, organized, improved, and willing to continue the war.


Table of Contents ** Previous Chapter (4) * Next Chapter (6)

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