The Odyssey of a U-Boat Commander

by Erich Topp

  Hartenstein's boat had been dispatched into the Gulf of Mexico to shell an oil refinery. The boat surfaced at dawn, its gun crew manning the 4-inch deck gun. In the excitement the gunnery officer forgot to have the stopper removed from the gun. The first round was set off, exploding in the barrel. The gun crew suffered light injuries; an ensign was severely wounded. Hartenstein issued orders to have the useless portion of the barrel sawed off, readjust the gun's ballistic characteristics, and resume the bombardment of the refinery. Later the boat stopped at Martinique, an island loyal to the Vichy government, to have the ensign treated in its hospital. Years later, after the war, my French friend Admiral Jean Sab- bagh, who was then also a submarine commander, told me that he had met the German ensign and had been able to assist him in that emergency. Thus this story has come full circle.

  After his return to France Hartenstein made the customary personal report to Admiral Donitz in Paris. The patrol had been successful and Donitz was in a good mood. "Hartenstein, is there anything I can do for you while you are here in Paris?" "Sir, if I only had a car, I would love to do some sightseeing." "But of course, Hartenstein, my personal car is at your disposal." Thus, later that afternoon Hartenstein, along with Karlchen Thurmann who had returned from patrol at the same time, were off in the Admiral's limousine. Around 8 r'rvi. the Commander-in-Chief asked his aide whether the car had been returned. The aide: "Sir, did you place the car at the two U-boat commanders' disposal?" "Yes, but of course not for so long. It is always the same story. If you offer these types your little finger, they'll grab the whole hand." Thus, the admiral had to call for a smaller car to take him to a scheduled visit to the city commandant of Paris. When he returned to his headquarters, his first words were, "Where is the car?" "The two submarine commanders have not yet returned." "As soon as they come back they are to report to me at once." Long past midnight, having done their share of bar hopping and gotten thoroughly acquainted with the city, Hartenstein and Thurmann returned at last. The aide-de-camp informed them, "You are to report to the Commander-in-Chief at once!" But when he realized that the two were far from sober, he added, "Well, I suppose this can wait until tomorrow." Hartenstein, however, felt himself called by his commander's voice. He straightened himself out, put on his uniform, and made his way to Donitz's quarters. Donitz, who was in the habit of working long into the night, was still up and complained bitterly that the two had taken advantage of his generous gesture. Hartenstein listened to the tirade unmoved, then saluted his commander and replied, slightly altering the famous lines attributed to BOrries Baron von Munchhausen, "On many a flag have I laid my hand swearing loyalty in this wicked war, many an admiral have I served . . . " before he simply turned around and left. The next morning at breakfast Donitz retold the whole story to everyone's amusement.

  Hartenstein commanded U 156 when she sank the Laconia off North Africa. The latter turned out to be transporting Italian prisoners of war, and when Hartenstein realized that the ship's lifeboats were far too few to accommodate passengers and crew he set in motion an international rescue operation. He alerted U-boats and merchantmen of other nations in the vicinity to the developing catastrophe by open messages on the international emergency frequency. Hartenstein himself took as many of the shipwrecked men aboard his boat as he could. To indicate the humanitarian nature of their actions, he and the commanding officers of the other submarines covered their boats' forecastles with huge Red Cross flags. This, however, did not stop U.S. "Liberator" bombers flying toward and over the scene from dropping bombs onto the U-boats and their shipwrecked guests. Clearly, this action not only violated international law but also went against the unwritten obligation to come to the aid of those in distress.

  The behavior of the Americans in this incident led to a controversial German countermeasure, namely, the order not to render help to shipwrecked sailors for fear of endangering one's own ship and crew. The Allied prosecutor at the International Military Tribunal in Nuremberg after the war characterized these instructions as an order to kill-an accusation that in the end could not hold up in the face of evidence. To illustrate this episode, I would like to quote an extract from a Fuhrer conference at the Reich Chancellery on September 28, 1942, at which Admirals Raeder and Donitz were present:

  Hitler continued: "I now want to address a matter we have dealt with in the past few days by way of radio-teletyper and telephone-the Laconia affair. To rescue the crews of sinking enemy vessels does not only endanger our own boats because of the ever-present threat of air attacks, but it goes against the very objectives of U-boat warfare. We must keep in mind what impact it has on enemy morale: He who sails for England must know he sails straight into death."

  At this point Hitler became more vehement: "It is absurd to supply shipwrecked sailors in their lifeboats with additional foodstuffs, as has come to my attention, or to provide them with sailing direction to the nearest coast. 1 hereby give the following order: Vessels and their crews are to be destroyed, including crews who happen to be in lifeboats." Hitler had uttered these words in a most determined tone and commanding voice. General Keitel, who stood next to Hitler, took out a notebook, placed it on the table, bent over it and recorded Hitler's directive. After a few moments of silence Hitler regained his composure and asked calmly: "Are there any other matters to discuss?" At that point Donitz stepped back from the table, stood at attention, and said, "No, my Fuhrer. It violates the honor of a sailor to shoot defenseless shipwrecked men. I will not issue such an order. My U-boat men, all of them volunteers, are carrying out a struggle with very severe casualties in the knowledge that they are fighting fairly for a good cause. The envisioned order would undercut their fighting morale. I beg you to withdraw the order." Hitler, again calm and using his Viennese dialect, replied: "Well, in that case you can do as you please. But no more aid and sailing directions." Keitel produced his notebook again and struck out the sentences he had taken down earlier. Throughout this episode only Hitler and Donitz spoke, nobody else among those present.

  This version of the conference is based on notes taken by Dr. Ing. Waas of the Navy's Construction Department immediately following the meeting. Its key points are also reflected in an entry of the Naval High Command's War Diary in December 1942: "The killing of survivors in lifeboats is not desirable, not so much because of humanitarian reasons, but because of damage to the morale of our own crews who would expect a similar fate for themselves if roles were reversed. " With few exceptions U-boat commanders followed these instructions.

  COMMANDER, 27TH U-BOAT FLOTILLA

  In Gotenhafen on the Baltic (today, Gdynia in Poland) I was responsible for the tactical training of German submarines before they joined combat squadrons for frontline service. To simulate Allied convoys I had at my disposal six to eight merchant vessels displacing between 6,000 and 10,000 tons; the U-boat tenders Wilhelm Bauer, Waldemar Kophamel and Saar; and as escort forces the ex-Norwegian torpedo-boats Lowe, Tiger, Leopard, and Panther, as well as three minesweepers. In addition we could call up Luftwaffe squadrons from the nearby air base of Rahmel to provide air cover.

  About every two weeks, eight to ten new U-boats joined the flotilla. With them we practiced day and night attacks against the convoy and its escorts, which cruised in waters between the Danish island of Bornholm and Libau on the Latvian coast. To render conditions as realistic as possible we were at sea in any type of weather, and the ships did not show their running lights. We used hand grenades to simulate depth charges. Our tactics reflected as accurately as practicable the experiences we had undergone in the Battle of the Atlantic.

  We were quite concerned over the question whether our training program took into account the changing conditions of the U-boat war at sea. We knew our losses were mounting. While early in the war, until June 1942, we had lost on average two to three boats per month, corresponding figures for the period since July 1942 had gone up frighteningly to about a dozen boats per month. In May 1943 no fewer than forty-two boats failed to return.
By the same token, Allied losses declined. In the early years of the war we had sunk more vessels than Allied and neutral shipyards could replace with new construction. This changed by the end of 1942, as the measures that President Roosevelt had announced in his famous speech of May 17, 1941 (before the U.S. entry into the war) began to take effect. He had said: "The Nazis are sinking three times the number of ships that British yards can build, and twice the number of British and U.S. shipyards combined. Our response must be: acceleration of the U.S. shipbuilding program and efforts to reduce our losses at sea." This led to the so-called Kaiser Program, the construction of the "Liberty" ships.

  What turned the U-boat war around? The reasons are primarily scientific and technological, but they also have to do with matters of organization and productivity. The whole question has been analyzed at some length. Here I would like to limit my discussion to a brief summary.

  Allied radar, used since 1940 aboard aerial surveillance aircraft and soon thereafter on escort vessels afloat, greatly hampered U-boat wolfpack tactics against convoys and in the end made them unfeasible altogether. High frequency direction finding devices, also known as Huff/Duff, could pinpoint the position of a U-boat within a radius of 25 nautical miles as soon as the boat went on the air to guide other submarines toward the convoy. The Allies also obtained the approximate position of a U-boat by automatically comparing radio bearings picked up by listening stations located around the Atlantic. In this way convoys could be routed away from likely U-boat concentrations.

  The "Leigh Light" system, combining radar and a powerful flashlight, enabled Allied aircraft to attack submarines at night when the latter surfaced to recharge their batteries. The "Hedgehog" allowed escort vessels to fire off a whole salvo of up to twenty-four depth charges with contact detonators, thus showering submerged U-boats with a hail of explosives. As U-boats sought greater depths to escape pursuit, the Allies dropped depth charges of higher destructive power to maximize effects. The asdic, or sonar underwater locating device, at first only useful if the searching vessel reduced its speed to below 10 knots, was improved to allow for its use at speeds of up to 18 knots. Moreover, the Allies vastly increased the number of escort vessels and surveillance airplanes and assured their cooperation in the search for U-boats. This effort culminated in the formation of so-called hunter-killer groups built around aircraft carriers.

  But by far the heaviest blow against the U-boats came when the Allies cracked the German radio cipher Schliissel M, or Cipher M. From about mid-1941 on, indications mounted that the enemy was reading some of our traffic, that is, he had access to our system of enciphering and deciphering. Again and again the men at the front alerted higher authorities of their suspicion. The leaders, however, clung to the view that Scliliissel M was absolutely secure because of the multitude of different combina tions the cipher machine allowed. If the naval leadership had taken these warnings seriously, relatively simple changes in the cipher procedure could have rendered it much safer, such as a superencipherment or the use of maritime positions as reference points rather than in absolute terms. At any rate, radio messages for or from U-boats should have been decoupled from ordinary naval traffic to increase cryptographic security.

  Already in March 1941 a British raid against the German patrol boat Krebs had garnered two of the rotor wheels used in the Schlussel M cipher machine. A similar surprise attack against the weather observation ship Lauenburg gave the British cryptographic material whose true nature has never been revealed but is referred to as invaluable.

  On May 9, 1941, Lieutenant Commander Fritz-Julius Lemp's U 110 delivered an attack against a British convoy before damage due to depth charges forced the boat to the surface. All hands abandoned ship after Lemp ordered explosives with time-delay fuses to be attached throughout the boat in order to scuttle it. The explosives failed to go off and the boat remained on the surface. When Lemp tried to swim back to U 110 to assure its destruction, he was shot dead in the water by the British who had closed in on the boat in the meantime.

  A specially trained British boarding party under Lieutenant David Balme entered the German submarine despite heavy seas. In the course of four hours Balme and his men transferred to the destroyer Bulldog by way of a small dinghy all the cryptographic material they could find, the boat's naval charts, the cipher machine with all current settings, the callsign book, the encipherment instructions, and the radio log, as well as the spare rotor wheels of the cipher machine. While this operation went on, the Bulldog hove to in order to prevent the Germans in the water from observing what was going on and possibly sending word back home. During their years in captivity the crew of U 110 remained isolated from other prisoners of war to forestall any kind of communication. Until the end of the war the German Naval High Command never learned about this incident.

  Throughout his daring exploit, Lieutenant Balme faced the constant threat that one or more of the explosives aboard the boat might blow up and kill his entire party. The raid would have far-reaching consequences. It meant the beginning of the Allied victory in the Battle of the Atlantic. Balme's name is rarely mentioned. At the time, in Bletchley Park in England, a group of British and Polish experts under Alan Turing, joined by Jewish emigres, developed the concept of a machine we would today describe as a computer. The latter enabled the enemy to break into Schlussel M and begin to read virtually the entire radio traffic not only of the German Navy but of the Wehrmacht in general. The British were able to decipher German messages for the remainder of the war, except for most of 1942. The process became so advanced that most signals were read within two to three days of their transmission. The British thus gained a precise picture of enemy dispositions. Convoys could be routed away from our U-boat patrol lines while Allied hunter-killer groups were ordered to move in on them.

  The "Enigma" cipher machine was originally developed for civilian applications. Patents for it had been obtained in several countries, including England in 1926. It could be bought on the open market. The military version of the Enigma contained a number of special features, but its basic principles were known. This circumstance substantially helped the Polish mathematicians make their initial technical analyses. Until the end of the war, German experts simply assumed that the incredibly high number of different rotor combinations for encipherment purposes rendered the Enigma safe to use. Even if one machine fell into enemy hands, the decipherment process was likely to be so time-consuming that the information learned would be of no use because events had moved on. While the German radio intelligence service could boast successes during World War II, the results of British efforts in the field remained a quantum leap ahead.

  What made the British so superior? They created a novel form of cooperation between the military and the scientific community. They called it operational research. The U.S. equivalent would be operational analysis. These groups of experts contained scientists from a variety of disciplines: physicists, chemists, mathematicians, astronomers, economists, psychologists, and the like. This, for example, was the composition of the team at Bletchley Park who worked together with experienced naval officers in the area of "operational and special intelligence." They collected all information they could possibly assemble about German U-boats, their tactics, armament, level of training, number and duration of war patrols, and even the personalities of the commanding officers. So-called mixed teams evaluated the information and passed their conclusions on to the forces engaged in anti-submarine warfare. After the war in Spain I happened to meet a former British intelligence officer who at one time had been in charge of tracing my and my boat's activities. He still remembered details about my war patrols that had long since slipped my mind. And what did we know about those who opposed and fought against us in that war? Practically nothing.

  The operational research teams developed these methods at a steady pace and kept them so secret that, while feeling their effects very clearly, we had no idea about their technological and operational dimensions.

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bsp; How did the U-Boat High Command react to the increasing effectiveness of enemy countermeasures; what was its response to the declining successes in the Atlantic? In May 1943 Donitz called together the commanders of all U-boat flotillas operating out of bases on the Bay of Biscay for a conference. Anyone who has attended similar meetings knows how strongly Donitz's charisma affected those under his command and how unlikely it was for serious criticisms to be brought forth. In this case Donitz's view and thus that of his flotilla commanders can be summarized as follows. To withdraw the U-boats from the Atlantic would free thousands of Allied aircraft, which in turn could be used against German cities. Likewise, hundreds of escort vessels could be diverted against German coastal shipping in the North Sea and cut off German supply lines to Norway. Churchill would be able to realize his dream of breaking through the Baltic approaches. A later argument would add that under such circumstances the evacuation of two million refugees across the Baltic at the end of the war would have become impossible. On May 31, 1943, Donitz flew to Fi hrer Headquarters to consult Hitler about the problem. Hitler concurred with DOnitz's views and added: "The Atlantic is our western perimeter. It is better to fight the enemy there than along the shores of Europe."

  A retrospective analysis of Donitz's arguments reveals that the types of Allied aircraft employed in anti-submarine warfare would have been impossible to use as strategic bombers against Germany, or only following extensive modification, on account of their flight characteristics and weapons systems. But why would the Allies go to any such trouble if their production of long-range bombers was quite sufficient to meet demands? To break through the Baltic approaches would have required major fleet units, not patrol craft or escort vessels. And finally, the continued U-boat offensive in the Atlantic could not prevent the Allied invasion of the continent. But even if one lets Donitz's arguments stand, it would have been wiser to bind Allied naval and air forces in the Atlantic by sending U-boats out on sporadic rather than massive missions, especially snorkel-equipped boats that could run their diesels even when cruising at periscope depth.