Dönitz had planned to equal or exceed the January U-boat offensive in the Americas in February with twenty-six or more boats. But owing to Hitler’s “Norway paranoia” and to the delays in the buildup of the Atlantic force caused by the Baltic ice, eight Type VIIs had to be diverted, temporarily, for the Iceland-Scotland patrol line. Moreover, believing that the Freetown area, unpatrolled since the Atlantis-Python disaster in November 1941, might be undermanned and/or unalert, Dönitz decided to send two Type IXs to the South Atlantic. The upshot was that only eighteen boats (nine IXs, nine VIIs) put out for American waters in February. Two-thirds (six of nine) of the Type IXs and nearly half (four of nine) of the Type VIIs were new, and because of the Baltic ice most had not completed a full training cycle.
Based on the experiences of Suhren in U-564 and Feiler in U-653, Dönitz had concluded that by following a Great Circle route and exercising stringent fuel discipline and limited mobility, the Type VIIs could operate in American waters for perhaps as long as ten days, or nearly as long as the VIIs in Canadian waters. He therefore directed that the difficult and less-productive patrols to Canadian waters be temporarily suspended and that all eighteen boats of the February group patrol United States and Caribbean waters.
The February boats were the first to benefit from the British inability to read four-rotor Enigma and thereby avoid known U-boat positions. While en route to the Americas on the same day, February 21, two new Type IXs, U-154 and U-155, attacked big convoys in the mid-Atlantic that were sailing in opposite directions.
Acting on the report of another boat, Walther Kölle, age thirty-four, in U-154 found the fast, strongly escorted, eastbound convoy Halifax 175. He got off the mandatory contact report, shadowed, then attacked doggedly, firing all fourteen internal torpedoes at a variety of ships, to absolutely no effect. After receiving his shooting report (ten unexplained misses, four “duds” on a tanker) Kerneval ordered Kölle to abort at high speed to Lorient. Upon his arrival it was discovered that the torpedo-data computer was out of calibration. Kölle had been bound for the Caribbean. Repairs and further training delayed his departure to March and, to Berlin’s consternation, diminished the U-boat campaign in the Caribbean.
Adolf-Cornelius Piening in U-155 found convoy Outbound North 67, which was westbound along a newly adopted, more southerly Great Circle route. Composed of thirty-five merchant ships, including many tankers in ballast, it was escorted by two old and two new American destroyers (Nicholson and Lea equipped with meter-wavelength radar) and a Canadian corvette. It was trailed by a 1,600-ton “rescue ship,” the Toward, which had accommodations for several hundred survivors and a medical staff, as well as one of the new shipborne Huff Duff sets, to take local bearings on U-boat shadowers for the benefit of the escorts.
Among the ships in the convoy was the 8,000-ton British tanker Empire Celt, equipped with a new and experimental antitorpedo device known as the Admiralty Net Defense. The device consisted of huge rolls of strong steel “nets,” which could be “streamed” from fifty-foot poles over the starboard and port sides in times of danger, or when sailing alone. During controlled tests, the nets had stopped British submarine torpedoes, but this voyage was the first “combat” trial of the device. Although the nets could not be streamed at speeds greater than 9 knots and they were difficult to handle and had to be replaced after each voyage, their advocates believed them capable of providing about 50 to 60 percent protection for freighters and tankers. The Admiralty Net Defense project manager, C.N.E. Currey, and a senior American submariner, George C. Crawford, were embarked on Empire Celt to oversee and observe the combat trial.
The rescue ship Toward DFed the contact reports of Piening in U-155 and gave the alarm. The destroyer Lea made a desultory search down the bearing for one hour, then returned to her position in the screen. Piening in U-155 evaded Lea, the three other destroyers, and the corvette, and in the early morning hours of February 22 attacked three ships with a bow salvo. His torpedoes sank the 8,000-ton British tanker Adellen and a 1,800-ton freighter. While the convoy continued on course, Toward and Nicholson picked up the survivors.
Inasmuch as the convoy was westbound, Dönitz directed all boats outbound to America that were near the convoy to converge. Two other new Type IXs, Erich Rostin in U-158 and Jürgen Wattenberg in U-162, and four VIIs homed on Piening’s beacons, and by late evening on February 23, seven America-bound U-boats were stalking convoy Outbound North 67 and maneuvering around the escorts. By sheer chance and improvisation, it became the first group attack on a North Atlantic convoy since the previous November 2, when the Germans drove Slow Convoy 52 back into Newfoundland.
The old hand Günther Krech in the Type VII U-558 was the next boat to attack. His strike on February 24 proved to be one of the most notable of the war. In five hours he sank five confirmed ships: four big tankers in ballast for 32,600 tons* plus a 4,400-ton freighter. Having shot all of his torpedoes save one, Krech returned to France, where he received unstinting praise from Dönitz and the usual buildup from Berlin propagandists.
Next, two Type IXs closed to attack: Rostin in U-158 and Wattenberg in U-162. Rostin hit and damaged a tanker. Then he and Wattenberg probably fired simultaneously at the tanker Empire Celt, which was in the process of streaming her Admiralty Net Defense. A torpedo broke through the net and hit amidships, making a gaping hole. She fell out of the convoy and broke in half. The bow sank. A tug from Newfoundland rescued forty-five men from the stern, including Currey and Crawford, and attempted to tow it to St. John’s, but the effort came to naught thirty-five miles short of the goal. The failure of the combat trial was a “grave blow” to the Admiralty Net Defense program, a British authority wrote. Nonetheless, the Admiralty fitted numerous ships of 8,000 tons or more with the device.*
The next skipper to attack was Ulrich Borcherdt in the new Type VII U-587. While outbound from France on February 13, Kerneval had diverted Borcherdt in U-587 and Viktor Vogel in the new sister ship U-588, and Otto Ites in the veteran U-94, to search for survivors of a Focke-Wulf Condor that had ditched. On February 15, Borcherdt had found five survivors in a dinghy and picked them up. He had then to rendezvous with a homebound boat to hand over the survivors. The first rendezvous, with Gerhard Bigalk in U-751, had gone awry; the second, on February 18, with Ernst Kals in U-130, had succeeded. It was a fortunate outcome for the Focke-Wulf crew, but in the search and the handover, Borcherdt had burned up a great deal of precious fuel.
The expenditure of fuel prompted Dönitz to make an extraordinary entry in his daily diary. However “satisfactory” and “natural” the rescue of the aircrew may “appear,” he wrote, “it is nevertheless always difficult to decide whether submarines on their outward voyage should be used to search for crews of planes that have been forced down. Under present conditions every drop of fuel is vital to the boats … It may well happen that a request for help will have to be refused for the sake of operational duties.” Upon reading this entry, the OKM commented that such was the value of experienced aircrews engaged in naval warfare that “a very serious reason would have to be given if such a request were refused.”
Coming up astern of the convoy to mount his attack, Borcherdt in U-587 saw the trailing rescue-ship Toward. She was burning “dim” side lights and was equipped with what Borcherdt believed to be “cable-laying gear.” Concluding from these observations that she might be a “decoy” or a “Q” ship, Borcherdt fired one torpedo at her. It missed or malfunctioned, leading Borcherdt and Kerneval to conclude later—and incorrectly—that the torpedo had been deflected by antitorpedo nets. Borcherdt then attacked the convoy, possibly hitting one tanker already fatally damaged by Krech. Escorts thwarted a second attack.
The U.S. Navy decorated the commanding officer of the American escort group, Albert C. Murdaugh in the destroyer Edison, for “particularly outstanding” work in defending the convoy. But in reality, it was a major disaster and embarrassment: eight British-owned or controlled ships (six tankers) sunk, for about 55,000 tons, and one British tanker damaged. The results, Dönitz logged, were “particularly satisfactory,” especially in view of the number of green skippers involved. The engagement powerfully reinforced his conviction that when sufficient boats were available to find, shadow, and attack, organized group operations against convoys could be resumed with every possibility of good success.
The reports from Krech and other skippers of antitorpedo nets on Empire Celt caused deep concern at Kerneval. It seemed “astounding” to Dönitz that a ship could make 9 or 10 knots with streamed nets. He immediately informed the torpedo technicians of this discovery, stressing the urgent need to develop a “countermeasure.” The only feasible countermeasure was a reliable magnetic pistol, which would run under the nets and explode the torpedo beneath the ship. The technicians had produced a new and improved magnetic pistol, but it was still undergoing tests. In view of the harsh punishment handed down to their predecessors for the failure of the original magnetic pistol, doubtless the technicians were reluctant to release the new pistol until it was faultless.
Altogether the U-boats had interrupted six cargo convoys on the North Atlantic run in February. These were the loaded eastbound convoys Halifax 173 and 175 and Slow Convoy 67. Three were the empty westbound convoys Outbound North (Slow) 61 and 63 and Outbound North 67. The Germans sank twelve ships from these convoys (six tankers) and three corvette escorts (Alysee, Arbutus, Spikenard). In addition, they damaged two tankers. This was hardly a “quiet” time, certainly no time for a wholesale transfer of escorts from the North Atlantic run to the East Coast, as suggested by Michael Gannon.
During the attack on Outbound North 67, or shortly thereafter, Wattenberg in the new Type IXC U-162 reported a serious casualty. The caps of two bow tubes had broken loose, blocking the other two bow tubes. He later managed to clear the two blocked tubes and patch the broken ones and requested permission to proceed, but Kerneval decided not to send a new skipper in a partly disabled boat onward to America. She was diverted to escort the incoming blockade-runner Osorno into France, but the rendezvous failed.
The unforeseen, unplanned attacks on convoys Halifax 175 and Outbound North 67, which resulted in the return of a boat (U-558) and two aborts (U-154, U-162), diminished the strength of the February group outbound to the Americas from eighteen to fifteen boats. Moreover, owing to the high expenditure of fuel in the rescue of the Condor air crew and the attack on Outbound North 67, Borcherdt in U-587 had to be limited to Canadian waters, reducing the group en route to United States waters to fourteen boats.
Unknown to Dönitz, the group was further reduced as the boats passed southbound through Canadian waters. On March 1 an American Navy Hudson, piloted by Ensign William Tepuni of the Argentia-based Patrol Squadron 82, spotted and attacked Ernst Kröning’s new Type VII U-656, about sixty miles southeast of Cape Race. The boat went down with all hands. She was the first confirmed U-boat to be sunk by U.S. forces and the first to be sunk in North American waters. Two weeks later, on March 15, a Hudson of the same squadron, piloted by airman Donald F. Mason, who had earlier won a DFC and great fame (“Sighted Sub. Sank Same.”) for a nonsinking, spotted and attacked Otto Gericke’s new Type IXC U-503, near the same area. She, too, went down with the loss of all hands. Both Tepuni and Mason were awarded DFCs; airman Mason was promoted to ensign.