VADM Sagerholm is a retired submarine officer who commanded USS KAMEHAMEHA (SSBN642) (Gold). As a flag officer he served as Commander South Atlantic Force, Executive Director of the President’s Foreign Intelligence Advisoly Board, and Chief of Naval Education and Training.
Part I posed the question as to why Germany lost the Battle of the Atlantic, since the German Navy “Arguably possessed the most experienced submariners of any nary in the world.” It provided tire background of the German Nary and its U-boat force leading up to the outbreak of the Second World War in September 1939, and described the relative advantages and disadvantages of tire U-boats versus their Allied adversaries. as well as the strategy and tactics employed by the U-boat force. The prima1y innovation in tactics was the use of wolfpacks to defeat the convoy system of the Allies, but wolfpack tactics required large numbers of submarines, yet Ger- many had only 22 ocean-going boats at tire outbreak of war. a disadvantage somewhat offset by tire dearth of Allied ASW escorts and aircraft. It then became a question of adaptation of strategy and tactics to accommodate resources, the ability to produce forces quicker than the other side, and the ability to create innovations in tactics, sensors and weapomy, including ships and submarines.
Part II described the early successes of the U-boat campaign; the insistence of Admiral Donitz to personally direct the employment of his U-boats thus requiring frequencies radio transmissions from the boats that revealed their position to Allied code-breakers and HFIDF intercepts; the failure of Hiller lo give top priority to the U-boats in resources and allocation of technical expertise, whereas tire Allies gave the Battle of the Atlantic first priority in all aspects: and discussed and analyzed these and other factors that affected the outcome of the battle. Implicit in tire discussion and analysis is the effectiveness of the early individual U-boat crews de- spite the handicaps under which they operated, a tribute to the German submariners, and a testimony to the potential of submarines in naval waifare. Part Ill concludes tire series, then provides a summation of the author’s findings and conclusions. The reader is invited to draw his or her own conclusions, and is encouraged to submit comments for discussion.
When the United States first entered the war, little was done to protect shipping along the east coast; coastal cities were not blacked out; ships were not convoyed; and the few resources available to the east coast penitent only an ASW patrol of meager proportions, hardly adequate to meet the size of the task. In addition, those few who were engaged in ASW were not trained for the task. Donitz dispatched five long-range Type IXC boats to the area of the east coast between New York and Miami, and six Type VllC medium range boats to the area east of Newfoundland and Massachusetts, this being the limit of the Type VII’s range. Called Operation Paukenschlag, which translates roughly as dmm beat, it was known within the U-boats as the second Happy Time. With virtually no protection and their silhouettes against the bright lights ashore providing clear outlines, the ships traveling the waters along the U. S. east coast were literally targets in a vast shooting gallery. In sixteen days, thirteen ships totaling 95,000 tons were lost, with seventy per cent of the tonnage being tankers carrying petroleum needed for the war. It was not until the April-May period that military and naval authorities ordered the coast to be blacked out. By the spring of 1942, U-boats had penetrated the Gulf of Mexico, where in May 1942 forty-one ships were sunk with a total tonnage of 218,867 tons. Every month had seen multiple sin kings in every area along the east coast and later in the Gulf of Mexico, a feat achieved with usually only six boats on station at any one time. The lack of sufficient numbers of long-range U-boats was painfully evident, the happy time notwithstanding, since the abundance of unprotected shipping, particularly tankers, if fully exploited, could have significantly affected the American war effort, delaying the production of ships and other war material, and perhaps causing the delay of Operation TORCH.
The U. S. Navy’s sparse escorts on the east coast as of December 1941 increased sufficiently by May to permit convoys to be organized, and by August, an interlocking convoy system had been established, covering the entire east coast. 1
Before 1942, American shipbuilding was producing an aver- age of one million tons annually. By 1943, however, merchant shipbuilding had reached over ten million tons and did not go below that figure for the remainder of the war. Warship building also ramped up in parallel, and carriers, cruisers, destroyers, submarines, and smaller ASW craft, as well as the thousands of different types of amphibious landing craft, were produced. The merchant shipbuilding production was sufficient not only to offset losses to U-boats, it actually increased the tonnage of merchant shipping available. At the same time, the ASW forces assigned to protect merchant ships at sea were being constantly reinforced and enlarged, and new classes of destroyer escorts were designed and built in record time, less than ten weeks in some cases from keel laying to commissioning. This phenomenal growth was accomplished by expanding jobs to include women, by clever engineering techniques involving the manufacture of prefabricated parts, and the use of assembly-line techniques that had been developed in the auto industry.
The new ASW forces also included escort carriers (CVE), relatively small carriers that displaced 10,000 to 15,000 tons at full load, with a top speed of twenty knots. Built on a merchant hull, the CVE carried a squadron of Wildcat fighters and a squadron of Avenger torpedo planes. Operating with a screen of four to six destroyers and destroyer escorts, the CVE was the nucleus of hunter-killer groups that were introduced to the Battle of the Atlantic in the late spring of 1943, the point at which the tide of the battle was beginning to turn in favor of the Allies. The use of long-range B-24s and B-l 7s had proved to be effective in forcing the U-boats to run submerged both day and night, but it was considered that aircraft at sea that could quickly respond to convoys under attack would significantly enhance the protection of shipping, and would further tip the scales in favor of the Allies. Ten CVEs eventually were added to the Atlantic ASW forces, and from May 1943 to May 1945 accounted for fifty-three U-boats, using a combination of HF/DF, radar and Ultra intelligence to detect, locate, and attack approaching U-boats. Typical of the hunter-killer operations was the deployment of Task Group 21.15, consisting of Croatan (CVE-25) with Escort Squadron 13: Frost (DE-144), Inch (DE-146), Huse (DE-145), Snowden (DE-246) and Barber (DE-161 ). Having departed Hampton Roads on 24 March 1944, TG 21.15 had proceeded to the area southeast of Nova Scotia where submarines were reported by intelligence to be operating. After days with no results, on 7 April, an Avenger on night patrol encountered gunfire from a surfaced submarine. Unable to make visual contact, the Avenger dropped sonobuoys, but heard nothing. At 0600, four aircraft covered the area of the contact with more sonobuoys, but still nothing was detected. At 0710, four destroyers from TG 27.6 that was operating in the vicinity took over the search, and at 0810, Boyle (DD-215) gained a strong sonar contact at a range of 950 yards. As Boyle ran in to make a depth charge attack, a periscope was seen just aft of the destroyer. The U-boat captain had come up to periscope depth to check the situation, and saw the horrifying spectacle of eleven depth charges settling into the water near his boat. He took the boat deep as the charges detonated, and in the noise, Boyle lost contact. Three more destroyers arrived, joined by Frost and Huse, and the nine ships commenced a box search, half to the east and the rest to the west. At 1542, some six and a half hours later, Champlin (DD-601) gained contact, but the rough seas made it difficult to hold the target. Huse was sent to assist, and the two regained contact and commenced coordinated attacks that forced the U-boat, U-856, to the surface. On the Huse, Sonarman 3/c Lawrence M. Rackson was at his battle station, gunner on the port bridge 20mm gun, when he saw the boat break the surface. After a short delay, Gennan sailors came streaming out of the conning tower, and Rackson and every other gunner in the vicinity opened fire. According to Rackson, they were under the impression that the U-boat crewmen were racing to their topside guns and were firing at them, an impression reinforced when an explosion hit the bridge of Champlin, fatally injuring the captain and wounding three others. 3 However, the Germans were unable to fire their guns, and were trying to escape their sinking boat and surrender. Later investigation revealed that the 20mm ammunition locker on the port side of Champlin’s bridge had exploded, causing shrapnel that showered the bridge. Champlin’s port 20mm gun had swung hard against the traverse restricting cam and dislodged it, allowing a round from the gun to hit the locker, causing the explosion. U- 856 was flooding aft and was settling by the stern when Champlin rammed the boat’s stern. Huse made a ramming run but missed. The boat was now flooding rapidly with the stern under water, and soon slid beneath the waves in its final plunge to the bottom. The captain of the U-boat and twenty-seven others were rescued from the rough seas. By the time TG 21 .15 returned to home port four months later, there were seven less U-boats in the Kriegsmarine …
The presence of the hunter-killer groups likely prevented additional attacks on convoys where submarines turned away rather than pressing an attack in the face of the air and escort coverage provided by a hunter-killer group. With their arrival in the ASW fleet, the CVEs helped the Allies to seize the initiative and go on the offensive against the U-boats. Land-based air had begun the change, but could not sustain it the way that the continually present hunter-killer groups could. 5 Although Admiral Donitz elected to continue the battle in the Atlantic for two more years, he did so with the realization that unless unforeseen events changed the course of the war in the Atlantic, his U-boats were fighting for a lost cause. He had lost the Battle of the Atlantic.
Donitz’s insistence early in the restoration of the U-boat force to build a preponderance of medium range boats reflected a failure to take the long strategic view in the event of war with Britain, a war that Donitz was convinced was going to occur, a war that he had said would inevitably include the United States. His initial decision to build a preponderance of Type VII boats may have worked satisfactorily if war had not occurred until his 300 Type Vlls and 100 Type IXs actually were in the fleet, but when the war started with the relatively small numbers on hand, he lost sight of the long view and became concerned with the need for numbers to execute his wolf-pack tactics. If he recalled his prediction that America and Britain would both be fighting Germany, it is not evident in his decisions and planning, which were solely focused on Britain. At that point, he would have been able to modify his program of U-boat construction to build the two types in equal numbers, thus giving his force a balance that would have enabled him to strike much more effectively against American shipping in the first months of America’s entry into the war. Donitz showed an apparent lack of the use of intelligence on American capabilities and what America might add to the war in the Atlantic. Even after President Franklin Roosevelt initiated various kinds of assistance to Britain, including the use of U. S. Navy escorts for convoys within America’s declared zone of neutrality, there is no evidence of DOnitz seeking information about the U. S. Navy. It would not have been difficult for an analyst following the force levels and disposition of American naval forces to have kept abreast of the lack of anti-submarine capability existing on the U. S. east coast. That realization would have been of value in looking ahead to attacking shipping off the coast of America, and could have prompted a recognition of the need for a better balance in his Submarine Force.
Donitz’s insistence on controlling the positioning of his boats right up to the point of attacking a convoy, combined with his refusal to recognize the hazard to his boats posed by the Allies’ use of HF/OF, both by land stations and at sea on escorts, undoubtedly contributed to the loss of U-boats. Based on the eports of escorts and their use of HF/OF to run down U-boats even before the latter were in attack position, it would appear that the losses in U-boats on the one hand, and the loss of opportunities to sink Allied shipping on the other hand, made the use of HF/OF doubly effective for the Allies. Much has been made in recent years of the impact of Ultra, the general premise being that the Allies were reading all German traffic in near real-time, and thus the U-boats never had a chance. In fact, the ability to read some of the traffic, never all, varied from time to time, depending upon the key used and whether the analysts at Bletchley Park had mastered that key, either entirely or partially. There were stretches of months without any information as to German operations or intentions because the analysts were unable to break a new code immediately, hardly the picture of a system that was all-knowing. At times, the German code breakers at B-Dienst were providing more information to the German Navy than was the case for Ultra and the Allied navies. Nevertheless, Ultra did play a significant role overall, and enabled a number of convoys to avoid U-boats or to anticipate their attack. It is interesting to note that neither side was aware of the ability of the other to read their traffic, and when Donitz questioned German intelligence because of the diversion of a convoy, for instance, he was assured that it was impossible to break the Enigma system. It must have been a source of deep frustration for Reader and Donitz to have been unable to convince Hitler of the importance of the U-boat campaign to the overall success of the war. Hitler’s inability to see the role played by the German Navy in clear terms had an impact on the course of the Atlantic battle in direct and indirect ways. Hitler’s insistence that the U-boats be sent into the Mediterranean to assist Rommel by interdicting supplies going to the British army showed his ignorance of U-boat capabilities and limitations, and his superficial view of how submarines operate. The Allied control of the air from bases on Malta made it virtually impossible for German submarines in the confined area of the eastern Mediterranean to operate on the surface, or to take aggressive action against British shipping entering Alexandria. The net result was a loss of the use of the boats in the Atlantic with little to show for their presence in the Mediterranean.
Indirectly, the lack of understanding of the importance of the Battle of the Atlantic by Hitler and his senior advisors and the resultant lower priority accorded the U-boats was a constant complaint of Donitz, and justifiably so. In the technology give- and-take that ensued in the Atlantic war, the German level of support for the U-boats did not match the efforts of the Anglo- American scientists and engineers. Furthermore, there was no imaginative use of academic talent similar to ASWORG in America, analysis that was sorely lacking in the German navy, and if available to Donitz, may have helped him to understand better the innovations he encountered on the part of the Allies, and may have assisted him in devising better tactics in response. As it was, the U-boat force was always in the reactive mode as opposed to the proactive, insofar as technology was concerned, with the exception of the anti-escort acoustic torpedo, and even here, the Allies quickly countered with a noisemaker devised by ASWORG that nullified the torpedo.
The failure of the magnetic detonators in the 1939-1940 period was a serious impediment to the possible success of the U- boat campaign, for the obvious reason that the U-boats were like wolves without teeth in trying to attack under those conditions. The Norwegian experience was especially traumatic, and was the catalyst for the extensive testing that eventually identified the problems in both the detonators and the torpedoes as well, problems that should have been discovered by the agency responsible for torpedo development. The number of submarines Jost and the extent of lost opportunities to sink ships because of these malfunctions can not be known, but intuition says that both must be substantial.
The German failure to establish a joint command to fight the Battle of the Atlantic resulted in a lack of air support for the U- boats to the extent necessary to produce positive results. Aerial reconnaissance using truly Jon grange aircraft could have made a major contribution to the German side in the Atlantic war. Locating convoys by air would have reduced or eliminated the inefficient use of U-boats in search tasks and allowed increased efficiency in their at-sea employment, a critical factor when a force is deficient in numbers, as was the U-boat force.
Was Donitz correct in his judgment that wolf-pack tactics were the answer to defeating the convoy system? In examining the history of the attempts to employ wolf-packs, one notes that there are a number of factors that come into play for example, the state of training and level of experience of the U-boats; the ability of the U-boat captains to recognize opportunities and seize them during the attack on the convoy; the visibility and sea state; the condition of the boat and of the crew (state of material readiness of the boat and amount of rest the crew has had); level of opposition encountered from escorts and ships in the convoy; presence of Allied aircraft; and just plain luck, all played a part. In addition, there was Donitz’s requirement of making his captains communicate in order to give him a reasonable picture of the situation, necessary since he also insisted on personally directing the wolf- packs and individual submarines. Anything that gives away the hidden presence of a submarine in effect nullifies the advantage of the submarine, all else being equal. It is arguable that the requirement for communications in the amount demanded by Donitz may well have nullified the theoretical effectiveness of the wolf-pack as a reliable tactic to employ against convoys. The successes realized were just as readily explainable by the particular attendant circumstances, and there were enough failures to justify questioning the reliability of the tactic.
The lack of a comprehensive and cohesive naval strategy is reflected in the decision to make the medium range Type VII boats the major force of the U-Bootwaffe, and further reflects the failure of both OKM and Donitz to recognize the need to attack Britain’s sea lines where the most effect could be realized, namely, the transportation of oil. It was oil that fueled the armed forces of all countries, and without adequate supplies of oil, forces were reduced to immobility in the case of ships, aircraft, tanks and trucks, vital elements of modern armed forces. In the initial stages of the war, when Britain was so short of ASW escorts and there were no long-range aircraft covering the Atlantic, Germany had the best opportunity to deliver a crippling blow to the British war effort, for industry relied on oil to a significant extent for its energy requirements, although British plants had access to the coal supplies of Wales and England. Once the United States was a formal combatant, DOnitz was able to send only five to six long range boats to attack the east coast shipping. In the case of America, there was no pipeline from the Gulf of Mexico to the northeast industrial concentration, rendering the tanker traffic a most vulnerable target for a concentrated U-boat campaign, but Donitz lacked the long range boats in sufficient numbers to be able to exploit the opportunity. In fact, there is no evidence that he recognized the vulnerability to the extent that he should have. While he did inform his captains that tankers were a preferred target, he did not require that the boats, with their limited load of torpedoes, save their eels for tankers, but instead continued to follow the practice carried over from the First World War of sinking any and all ships sighted, rather than concentrating on the high value targets. Ninety-five per cent of oil and petroleum products used by the east coast came by tanker, a statistic that should have been a basic strategic consideration of the OKM and of Donitz, since “movement of oil and petroleum products was among the most vital of wartime enterprises.” 7 Rather than seeking to attack a key center of gravity, however, the Germans followed the approach of simply counting ships sunk, regardless of the value of each ship in a strategic sense, permitting thus a waste of resources since torpedoes were in limited supply on each U-boat, and when expended, a boat had to return to base to replenish unless it could affect a transfer from a supply U-boat.
Midway through the war, Donitz saw the need to keep boats on station longer than their individual capacities would permit, and had resorted to building large boats carrying fuel, food and torpedoes for transfer at selected rendezvous points. This endeavor met with limited success at best. Initiated in the spring of 1942 when three Type XIV boats were commissioned, each of some 1,700 tons, carrying 700 tons of fuel from which was available for transfer 400 to 600 tons, depending on the supply boats transit needs. In late April and early May, twelve Type Vlls and two Type IXs were refueled northeast of Bermuda, and by the middle of June, twenty out of thirty-seven boats in the western Atlantic and Caribbean had been refueled, and were ordered to attack shipping ranging from Hatteras to the West Indies. At the same time, however, the U.S. Navy had begun convoying on the east coast, and by June, had also instituted convoys in the Caribbean. Thus, what had been a fruitful source of targets from January to April suddenly became barren of targets for the U-boats. Once again, the failure of Donitz and OKM to take the long-range strategic view at the outset of war had denied the U-boats the ability to exploit to the fullest the opportunities when they were available. The system of using large U-boats to resupply boats at sea was fraught with difficulties, and required good weather and a low sea state, as well as excellent ship-handling and skilled seamanship by the U-boats. Furthennore, the supply boat’s crewmen were on deck for long hours, handling the cumbersome refueling hoses and the lines controlling transfer of torpedoes and food, in conditions of rolling and heaving decks and the ever-constant risk of being spotted by an enemy aircraft or destroyer. At best, the system was a stop-gap measure that attempted to compensate for the lack of long-range boats. Once the Allies discovered the milch cows as they were dubbed by the U-boats, they rightly gave their destruction a high priority, and by August 1944 the operation had become so dangerous it was abandoned.
It can be argued that concentrating submarines against a specific type of shipping would result in concentration of enemy forces to counter the submarines, and that is so if the enemy has sufficient forces to do so. But early in the war, the British ASW forces were in short supply, and a large reduction of oil and petroleum products could have had a telling political effect on Britain at a critical point early in the war, the fall of France.
It is also instructive to compare the priority accorded the Battle of the Atlantic by the British prime minister, Winston Churchill, with the lack of same by Hitler. It was the former who had named it, and it was he who had given it the highest priority in his directive issued on 6 March 1941 , a priority that was responsible for the resources of material and labor which resulted in the continual increase in strength and numbers of the forces assigned the task of fighting the war in the Atlantic. When America entered the war, Churchill had already persuaded President Franklin Roosevelt of the strategic importance of the Atlantic in the eventual defeat of the Axis in Europe, and the vast resources of American industry played a significant role by producing literally prodigious amounts of warships and merchant ships, such that by war’s end, the Allies possessed more ships than at the beginning despite the numbers sunk by the U-boats. Against this capability, the longer the war lasted, the less chance of success did Donitz’s strategy have; once America was in the fight, sinking more ships than could be replaced was a losing gambit. The best chance for success was early in the war, and the German high command did not apparently understand that, since the war in the Atlantic never seemed to have been given its due in the Gennan grand strategy. Although Donitz appreciated the importance of the U-boat campaign to the total war effort, he was fixated on numbers rather than quality of ships sunk as the gauge for measuring results, and thus he continued on a course of action that was increasingly likely to fail. His memoirs are full of such phrases as “fortunate in our estimates” and “my feeling was … ” or similar statements that indicate the decisions for employment of the U-boats were largely seat-of-the-pants intuitive guesswork, devoid of any analysis of a concrete nature, and the general approach of the U-boat command as the war progressed was one of reaction to Allied initiatives rather than a proactive seizing of the initiative. Attempts to be proactive through the development and building of the Type XX.I and Type XX.III boats were too late to be effective, having been of lower priority in the overall production of the implements of war. As it was, the hasty construction of the XX.I and XX.III boats resulted in submarines that were designed for a depth of 1200 feet being unsafe below 700 feet due to poor structural integrity, as shown in post-war tests conducted by the U.S. Navy. 10
In conclusion, it is evident that no one factor can be identified as causing the defeat of the U-boats in the Battle of the Atlantic; rather, it was a complex interweaving of a number of factors which produced the outcome. The person and personality of Donitz loom large, but there were factors over which he had no control that also played a role, the onset of the war well before the German Navy was prepared, for instance. On the other hand, he was responsible for the decisions made in response to those factors, particularly the failure to adjust his strategy to the lack of numbers at the outset of the war. Concentrating on the tankers in September 1939 would not have guaranteed success, but it would seem to have had a better chance, at least early in the war, than did the unimaginative tactic of simply sinking any ship in sight. In summary, the primary causes of defeat of the U-boats were
- The primacy of the Battle of the Atlantic in Allied priorities versus the inability of Hitler to see its importance, with consequent lack of a comprehensive strategy, and lack of support in weapons and sensor research, construction, and air support. The consequent lag in electronics technology was a constant hindrance to U-boat operations.
- No joint Atlantic command to provide coordination of air and submarine assets, and to discern special needs such as development of truly long-range aerial reconnaissance capability. The latter was a critical shortcoming for the Gennans in the Atlantic campaign.
- The inflexibility of Donitz regarding Allied use of HF/OF, causing needless loss of numbers of U-boats.
- The insistence of Donitz on controlling wolf-packs via numerous radio transmissions from his boats, opening his boats to detection and location by the Allied ASW forces.
- Over-reliance on Type VII medium-range boats at the expense of sufficient numbers of long-range boats with greater endurance, so that opportunities to exploit Allied vulnerabilities were lost.
- Allied convoy system, which created a set of conditions that were favorable to the Allies so long as the U-boats followed the tactic of attacking any and all convoys, rather than those containing ships of the most value to sink, such as tankers. Convoy system also increased the difficulty of locating ships to attack. Intelligence received from 8- Dienst and other intelligence sources could have identified which convoys were of most value to attack, and operational analysis could have been used to detennine the optimum tactics to employ.
- Allied coordinated employment of escorts, hunter-killer groups, and land-based long-range aircraft.
- Onset of war in 1939 before the German Navy was adequately prepared, and the failure of 0KM and Donitz to adjust accordingly.