Although the patrols to West African waters during the late summer of 1941 had produced scant returns and there were no German resupply ships immediately available, and British diplomatic pressure had closed the Spanish Canaries to U-boats, Dönitz believed patrols to this area should be continued. The presence of U-boats in the South Atlantic forced the British to convoy and to draw ASW forces from elsewhere, and kept pressure on the flow of British supplies to Egypt and the Middle East going via the Cape of Good Hope. Accordingly, two waves of four Type IXs sailed for the Freetown area in the early fall.
The first wave achieved very little. Believing that British ships might be taking cover in the American hemispheric defense zone, which extended to South American waters, Dönitz sent two of the four boats across the “narrow neck” of the South Atlantic to Brazil: Richard Zapp’s U-66 and Wilhelm Kleinschmidt’s U-III, the first two U-boats to go south of the Equator.* Kleinschmidt sank two big freighters sailing alone: a 5,700-ton Dutchman bound for Egypt with a cargo of aircraft, and an 8,400-ton Britisher bound for England with a cargo of pig iron and manganese.† Zapp in U-66 sank the 7,000-ton Panamanian tanker I. C. White 600 miles south of the Equator. Patrolling the once-rich hunting grounds off Freetown, Klaus Scholtz in U-108 and Ritterkreuz holder Günter Kuhnke in U-125 were outwitted by British intelligence and ASW forces. Neither boat sank a single ship.
The second wave of four boats had better luck—at first. Southbound off the coast of Africa on September 21, Dönitz’s son-in-law Günter Hessler in U-107 found a northbound convoy, Sierra Leone 87. It was composed of eleven big ships and five ill-trained, ill-equipped escorts, led by the ex-Coast Guard cutter Gorleston. Inexplicably, the escorts had not topped off fuel tanks in Freetown; none was fully combat-ready.
When Hessler reported the convoy, Dönitz ordered him to shadow until he could bring up the other three southbound boats of the second wave. The first to arrive was Karl Friedrich Merten in U-68, making his first patrol in South Atlantic waters. In the early hours of September 22, Hessler and Merten attacked the convoy. All four of Hessler’s torpedoes malfunctioned or missed, after which an engine failed, forcing him to withdraw for repairs. Merten fired three torpedoes. He claimed sinking two ships for 14,000 tons and damage to a 7,000-ton tanker. In fact, he sank no ships, but hit and severely damaged the 5,300-ton British freighter Silverbelle.
The escorts fired star shells and churned around, but they mounted no organized counterattack. Three of the five, including Gorleston, stood by the damaged Silverbelle, whose crew was desperately attempting to make repairs. Falling well behind the convoy, Gorleston took Silverbelle in tow until Derby House ordered her, as well as the corvette Gardenia, to rejoin the convoy forthwith. Another of the escorts, the small Free French minesweeper Commandant Duboc, took Silverbelle in tow. A week later Duboc ran low on fuel and was forced to return to Freetown with Silverbelle’s crew, leaving the hulk still afloat.
Early the following night a third southbound boat caught up with the convoy. She was U-103, commanded by Werner Winter, age twenty-nine, making his first full Atlantic patrol as a skipper. He closed the formation after dark, fired a salvo of five torpedoes, and claimed sinking four ships for 24,000 tons and damage to another of 6,000 tons. In reality, he hit and sank two big freighters for 10,600 tons. The three escorts, including the corvette Gardenia, rescued survivors, but again conducted no counterattacks. Low on fuel, Gardenia departed when the Gorleston caught up, leaving a total of three escorts and eight merchant ships.
Merten in U-68 closed that night for his second attack. He saw a damaged freighter and a damaged tanker, he reported later, but he bravely chose to attack one of the “destroyers.” He set up on and fired at one “destroyer,” but both torpedoes missed. It was then discovered that U-68’s batteries were too low to permit a dive, so Merten was forced to break off the attack, withdraw, and commence a battery charge.
The fourth and last boat to arrive was the U-67, commanded by Günther Müller-Stöckheim, age twenty-seven. Commissioned on January 22, 1941, under the command of Ritterkreuz holder Heinrich Bleichrodt (who later went to U-109), the U-67 had been diverted during the spring and summer to R&D experiments.* Until now, she had not made a real war patrol and her long-suffering crew was eager for a kill.
As Müller-Stöckheim closed to attack, a valve in the main ballast-tank air manifold failed. The engineer logged in his personal diary: “I had to report to the commander that other minor defects had occurred and that the boat was not fully fit to dive.” Undeterred, Müller-Stöckheim pressed the attack, firing three torpedoes at what he believed to be a 7,000-ton ship. He hit and sank a 3,800-ton British freighter, which went down so quickly that it capsized and sucked under its three lifeboats. The escorts rescued the survivors but again conducted no counterattack.
Having repaired his engines, Günter Hessler in U-107 caught up with the convoy in the early hours of September 24. In this second attack, he claimed sinking three ships for 26,000 tons, including a 13,000-ton tanker. He actually sank three freighters for 13,600 tons. In his report to Kerneval, Hessler stated that only one ship of the convoy remained and that it was closely guarded by escorts.
Upon receiving Hessler’s report, Dönitz called off the attack, well pleased at the results. Based on reports from the four boats, he estimated they had positively sunk five ships for 41,000 tons, possibly sunk four more for 24,000 tons, and damaged two for 12,000 tons. Hence, he logged, the entire convoy, “except one ship,” was “wiped out.” In reality, the four U-boats had sunk only about half of the convoy: six of the eleven ships for 28,000 tons. At that time a seventh ship, Silver-belle, under tow by Duboc, was still struggling to stay afloat.
In due course the remaining four ships of Sierra Leone 87, escorted by Gorleston and two other escorts, reached the British Isles. The failure of the escorts to prepare properly for the mission and to carry out vigorous counterattacks drew harsh criticism from Derby House. An account of the failures was circulated to ASW forces as an example of what not to do, and Derby House took steps to ensure that the skipper of Gorleston did not again command an escort group.
The four boats that had attacked Sierra Leone 87 went separate ways. Winter in U-103 and Hessler in U-107 proceeded independently to patrol off Freetown. Also outwitted by British intelligence and ASW forces, neither boat sank another ship. Müller-Stöckheim in U-67 and Merten in U-68 could not immediately go further south. A man on U-67 was ill with a venereal disease; Merten in U-68 had fired most of his torpedoes.
When apprised of the situations on U-67 and U-68, Kerneval directed the two boats to rendezvous with Kleinschmidt’s U-111, which was en route home from the South Atlantic. The plan was that a doctor on board U-68 was to examine the sick man on U-67. If the doctor could not administer a cure, the man was to return to France on U-111. At the same time, Merten in U-68 was to take on torpedoes from U-111. In that way both U-67 and U-68 could resume their voyages to the South Atlantic.
Kerneval ordered the three boats to rendezvous in a remote area: Tarafal Bay, Santo Antão Island, in the Portuguese Cape Verde Islands. The British codebreakers intercepted several messages relating to the rendezvous, including an indiscreet one from Kleinschmidt in U-111, which mentioned Tarafal Bay by name. The Admiralty ordered the big River-class submarine Clyde, commanded by David Ingram, which was on ASW patrol in the Canary Islands, to go to Tarafal Bay and attempt to sink all three U-boats.
This order to act tactically on Enigma information was risky. Until then the Germans had not used the Cape Verde Islands for U-boat operations. Should Clyde fail to sink all three boats, a report of her appearance in remote Tarafal Bay at the exact moment of the first U-boat rendezvous there was certain to raise deep suspicion in Germany that Enigma had been compromised.
As scheduled, Merten in U-68 and Kleinschmidt in U-111 arrived in the bay on the evening of September 27. The boats anchored side by side about 200 yards offshore. While Merten and Kleinschmidt had dinner, the crews transferred four torpedoes from U-111’s topside canisters to U-68. Neither skipper felt quite at ease in those confined, unknown waters. Shortly before midnight both boats got under way and stood out to sea, intending to return the following night to meet Müller-Stöckheim in U-67.
At that same moment, Clyde nosed into Tarafal Bay on the surface. Her bridge watch saw U-68 and Ingram turned to shoot a bow salvo. Before he could fire, however, he caught sight of U-111. Believing U-111 was coming in to ram, Ingram broke off the attack on U-68 and turned to deal with U-111. But when Kleinschmidt in U-111 saw Clyde, he elected to crash-dive rather than ram, a decision that drew harsh criticism from his men. Clyde passed directly over U-111, with mere inches between the two hulls.
When U-111 disappeared from view, Ingram resumed his attack on U-68, which was still unaware of his presence. Remaining on the surface, Ingram fired all six bow tubes at U-68, but Merten’s alert bridge watch saw the torpedoes approaching and he turned U-68 on a parallel course and crash-dived. The torpedoes missed, but two hit the distant shore and exploded. Confronting two alerted, submerged U-boats, Ingram dived Clyde to reload his torpedo tubes and search for his quarry by hydrophone.
While the three submarines were submerged in the bay, groping blindly for one another, a fourth was entering on the surface. She was Müller-Stöckheim’s U-67. When he heard the two torpedo detonations, he was shocked and puzzled—and promptly dived. He picked up the swish of propellers on his hydrophones, but could see nothing through his periscope. Prudently he decided to surface and withdraw to open sea.
Shortly after U-67 surfaced, Müller-Stöckheim caught sight of a “shadow” on his port bow. This was Clyde, which had reloaded tubes and surfaced with her deck gun manned. Ingram saw U-67 at the same moment and turned Clyde to ram. Recognizing the “shadow” as a big River-class British submarine on a collision course, Müller-Stöckheim backed his engines emergency power and put the rudder hard over. The result was that U-67 avoided being rammed but unintentionally hit Clyde a glancing blow in her stern.
The two submarines broke clear and dived. Clyde was not seriously damaged; U-67 was a mess. Her bow was bent around at a 90 degree angle and three of her-four bow torpedo tubes were inoperable and leaking. Since the crew could not repair the damage, she had to abort and return to France, taking the man with venereal disease who was partly responsible for this disastrous rendezvous.
During the ensuing day—September 28—the four submarines hauled out to sea and scattered. Müller-Stöckheim in U-67 got off the first report to Kerneval: He had heard “two explosions” in the bay and had collided with a British submarine and had to abort. Fearing that Clyde had sunk U-68 or U-111 or both, Dönitz asked for position reports. Kleinschmidt spoke up to report that a British submarine had indeed fouled the rendezvous and that it had attacked and may have sunk U-68. Merten in U-68 finally reported that he was not sunk or damaged and that he had taken on torpedoes from U-111 and wished to continue his patrol to the South Atlantic. Since the damaged U-67 had to return to France, Merten requested a second rendezvous with her to take off whatever fuel and torpedoes she could spare. Kerneval arranged the second meet in a remote cove on the coast of Africa in Vichy French Mauritania. The U-67 then limped back to France and the U-68 proceeded to the South Atlantic.
After leaving the Cape Verde Islands, Kleinschmidt in the homebound U-111 set a course for France. Since his track was to take him west of the Canary Islands, close to the place where the boats of the second wave had attacked Sierra Leone 87, Kerneval directed him to be on the lookout for the abandoned hulk of Silverbelle, wrecked by Merten in U-68.
While looking for the hulk on the morning of October 4, Kleinschmidt saw smoke on the horizon. Believing he had found a big freighter, he turned U-111 to attack. The smoke was coming from a coal-burning armed trawler, Lady Shirley, which had come out from Gibraltar to salvage Silverbelle or, possibly acting on Ultra information (the records are not clear), to intercept U-111. As U-111 closed, the lookout on Lady Shirley spotted her conning tower at a distance of about ten miles. The lookout thought it was the funnel of a merchant ship, but Lady Shirley’s captain, A. H. Callaway, turned toward the object on the “off chance” that it might be a U-boat. Still believing the trawler was a big freighter, Kleinschmidt dived to position U-111 for a submerged torpedo attack. Listening to Lady Shirley’s screws, the hydrophone operator warned Kleinschmidt that the target was a small ship drawing very close, but Kleinschmidt stubbornly clung to his conviction that she was big and pretty far off.
Coming up pinging, Lady Shirley got a good sonar contact at 1,600 yards. She ran in and dropped four depth charges, two set for 150 feet, two set for 250 feet. These exploded while U-111 was still at periscope depth—fifty feet—and did little damage. In response to this rude and shocking development, Kleinschmidt ordered a gun action. He surfaced U-111 close to Lady Shirley, but both diesels malfunctioned and the engine room filled with dense choking smoke, impeding repairs and making another dive inadvisable.
Thus crippled, Kleinschmidt attempted to proceed with the gun action. But Lady Shirley was bearing in, firing her 4” gun and smaller weapons. Kleinschmidt got his 20mm gun on the bridge manned, but the close, accurate, and continuous fire from Lady Shirley prevented the Germans from running down onto the main deck to man U-111’s 4.1” gun.
Like two sailing ships of yore, the Lady Shirley and U-111 lay side by side, pumping shells at one another from point-blank range. Having seized the initiative, Callaway in Lady Shirley never relinquished it, and the German gunners could not get to the big deck gun. In the exchange of fire, Lady Shirley incurred five casualties (one killed, four wounded) in her fourteen-man crew, but she killed seven Germans, including the 20mm gunner and all three line officers: Kleinschmidt, first watch officer Helmut Fuchs, and second watch officer Friedrich Wilhelm Rösing, younger brother of Ritterkreuz holder Hans-Rudolf Rösing, who was then commanding Combat Flotilla 3 in La Pallice.
Upon the death of the three officers, a prospective commanding officer, Hans Joachim Heinecke, who had been helping with the malfunctioning diesels, assumed command of U-111 and ordered her abandoned and scuttled. The engineer opened the vents and the forty-five survivors, including five wounded, jumped overboard. Nineteen minutes after the start of the gun battle, U-111 plunged under for the last time.
The triumphant little Lady Shirley fished the survivors from the water and set a course for Gibraltar. One of the wounded Germans who had lost a leg died en route and was buried at sea, leaving forty-four of the fifty-two-man crew. The survivors were shocked and humiliated that Kleinschmidt, a merchant marine veteran, had mistaken a trawler for a big freighter and that the big and powerful U-111 had been bested by a lowly British trawler manned by fourteen men.
As in the case of U-570 and U-501, from which German prisoners had been taken recently, British intelligence officers noted well the inexperience of the U-111 crew. Kleinschmidt, who came from torpedo boats and cruisers, had been in the submarine arm only one year. The first watch officer, Fuchs, age twenty-four, had been in the Navy only four years. Normally a second watch officer, Fuchs was temporarily serving in the higher post because the regular first watch officer had injured himself ashore and did not sail. Rösing, crew of 1936, was actually a year senior to Fuchs, but he had only recently transferred from the Luftwaffe and had no prior experience in submarines and was therefore serving as second watch officer. Among the petty officers, only five had served in submarines before joining U-111 but, as a British report put it, only two of the five would have been considered “experienced” by prewar standards. Some of the enlisted men had been in the Navy only ten months.
Despite repeated assurances from the OKM to the contrary, the appearance of the British submarine Clyde in Tarafal Bay fouling the rendezvous of U-67, U-68, and U-111 convinced Dönitz that the British were reading naval Enigma. He logged on September 28: “It appears improbable that an English submarine would be in such an isolated area by accident. It is more likely that our cipher material is compromised or that there has been a break of security.” Accordingly, an emergency modification to naval Enigma was put into effect on October 1, which blinded Bletchley Park. But within seven days British codebreakers broke back into Enigma and read it currently until October 12, when, as related, another blackout of two days occurred.
Prodded by Dönitz, the chief of Kriegsmarine communications, Vice Admiral Maertens, intensified his new and supposedly comprehensive investigation into Enigma security. On October 24 Maertens turned in an eighteen-page report to the OKM and Dönitz in which he reaffirmed Berlin’s unshakable belief that Enigma was safe. Maertens dismissed the appearance of Clyde at Tarafal Bay as doubtless the result of a routine ASW patrol. Had the British planned a “trap” based on Enigma decryptions, he wrote, they would certainly have sent more than one submarine. He likewise dismissed other worrisome events that Dönitz had described, attributing them to British DFing or sightings by enemy and neutral ships and aircraft. As to the possibility that the British had recovered the Enigma from the captured U-570, he could not say positively one way or the other, but there was as yet no evidence they had, and in any case, U-570 carried Enigma keys that were to expire soon.
The Maertens investigation was slipshod. The American historian Timothy Mulligan, who unearthed the Maertens report, aptly wrote in his analysis that by focusing narrowly on the Tarafal Bay incident and several others, Maertens altogether neglected the main point: the difficulty U-boats had in finding convoys on the North Atlantic run from Canada to the British Isles and vice versa.
It may well be that Maertens viewed the investigation as a waste of time—old history. Two steps were already afoot to greatly increase the security of U-boat codes:
• Commencing about October 5, U-boats were to begin using a special Enigma net, separate from the standard Kriegsmarine Home Waters net (Heimisch; Dolphin in Britain). The Germans called the new U-boat net Triton; the British called it Shark. Access to Triton (Shark) other than by operating U-boats was to be severely limited to eight naval commands and the six Atlantic U-boat combat flotillas. U-boat crewmen not on patrol were barred from listening to the circuit. No weather ships, of course, were to use the Triton (Shark) net, so the chance of again capturing the keys, other than from a U-boat (à la U-110), was remote.
• A new Enigma machine employing four rotors on the axle (rather than three) was nearly ready for distribution to U-boats for use on the Triton (Shark) net. The Germans believed that by employing a fourth rotor and by changing the selection and order of all four rotors frequently, the naval Enigma would be even more difficult—indeed, impossible—to break by the most sophisticated and ingenious mathematical theories. The enemy would have to capture both a four-rotor machine and the daily keys. If the keys were also changed frequently, success from captures would be at best short-lived.
British codebreakers at Bletchley Park had found clues in Heimisch (Dolphin) traffic that a new Enigma net for U-boats (Triton, or Shark) and a new machine employing four rotors were in preparation. On October 7, after intercepting some early German tests of Triton (Shark) traffic in four-rotor Enigma, which proved to be unbreakable, they described it as “an ominous sign of worse things to come.” They warned that Shark could not be broken without a new, complex, high-speed “four-rotor” bombe, but, the official British historian wrote, they failed to stress the urgency of designing and building such a bombe. Some even doubted that a workable four-rotor bombe could be built.
In fact, Bletchley Park was neither mentally nor physically capable of confronting a new challenge of this magnitude. Its chief cryptanalysts, Gordon Welch-man and Alan Turing (in Hut 6 and Hut 8), were utterly swamped with work and exhausted; the dozen “three-rotor” bombes in operation were incapable of absorbing further loads. Moreover, owing to the need for utmost secrecy, the importance of the work at Bletchley Park was not appreciated or understood by those not in the picture and, as a result, London bureaucrats had not given the codebreakers the support they required and deserved. On October 21 Welchman and Turing and two other senior cryptanalysts sent an extraordinary letter directly to Churchill, begging for help. They pointed out that owing to “shortage of staff” and “overworking,” the naval team in Hut 8 had to cease night shifts, with the result that “the finding of the [Enigma] naval keys is being delayed at least twelve hours every day.” A similar situation existed in Hut 6, which was working on Luftwaffe and Wehrmacht Enigma.
In response to the letter, Churchill directed that Bletchley Park be given “all they want on extreme priority.” The shortages of personnel were swiftly overcome, but the difficult—perhaps impossible—four-rotor bombe was not pursued with vigor. It was not until December that anyone tackled a possible design; another month passed before a technical team could be assembled to pursue this daunting task.