Black May

by Michael Gannon

  There were no further incidents during ONS.7’s passage until shortly after midnight on the 17th, when Iller boat U-657 (Kptlt. Heinrich Göllnitz), on her first combat patrol (out of Norway), put two torpedoes, two minutes apart, into the 5,196-GRT British steamer Aymeric, which had the unhappy distinction of being the last northern transatlantic ship under the red duster to go down in May or in the whole of the month that followed. The ship’s foremast collapsed; the hatches from No. 1 hold, the rafts from the fore rigging, and even the derricks were blown over the side; while slag ballast was strewn everywhere. Moments after the second torpedo, the ship’s boilers exploded, fracturing both port and starboard sides of the vessel. A number of the Lascar crew panicked while lowering the boats and lives were lost as a result. The ship went under five minutes after the first explosion. Men found themselves swimming in bitterly cold water, where many became stiff and sank. The survivors were rescued by a rescue ship and a trawler. Of the seventy-eight-man crew, fifty-three died. It was one of the worst human tolls of the month.44 But the drowned and frozen would not go unavenged.

  H.M.S. Swale, SO of EG B5, ordered “Artichoke” and swept out herself 6,000 yards astern of the victim’s position. There, at 0138, she obtained an asdic contact classified as “submarine,” bearing 285°, range 900 yards. Three minutes later, Swale was on top of the contact with ten D/Cs. When no evidence surfaced, she fired Hedgehogs at 0203. There were no explosions, but the bridge observed patches of light oil in which, peculiarly, small yellow flames appeared. The River-class frigate then fired a second H.H. salvo at 0224 and, 33 seconds later, heard a single loud explosion followed after 107 seconds more by two “muffled” explosions. At 0231, just to be sure, Swale dropped a ten-pattern set to 150 and 350 feet over the position, and was rewarded by two loud explosions five and a half minutes later and a second appearance of oil patches. Aymeric s slayer would not surface again. The position where forty-four young Germans paid the stern price was 58°54'N, 42°33'W.45 Convoy ONS.7 continued its passage without further hindrance, joined briefly from daylight on the 18th to 1100 on the 19th by the four-destroyer Third Escort (Support) Group. Close escort B5 was relieved by the Western Local Escort Group at WESTOMP on the 21st and the convoy entered Halifax four days later.

  As long before as February, reckoning on the eight-day cycle for departures of ONS and SC convoys, Commander Peter Gretton, SO, Escort Group B7, had set a date at the end of May when he pledged he would be in London to meet a Wren whom he had courted at Gilbert Roberts’s Tactical Unit (WATU), and there exchange vows of matrimony with her in St. Mary’s, Cadogan Square. At 1330 on the 14th of the month, his prenuptial voyage began, as a now-familiar company of warships—Duncan, Vidette, Tay, Loosestrife, Snowflake (her mate, the injured Sunflower, to follow), and Pink—slipped their moorings at St. John’s, Newfoundland, and bore eastward through the inevitable fog. Joining the escort at sea were the rescue trawler Northern Spray, also of ONS.5 fame, and an extra corvette, H.M.C.S. Kitchener. At 0600 on the 15th, still in fog, B7 met the convoy entrusted to its care, SC.130, consisting of thirty-nine merchant vessels, not including a rescue ship, Zamalek.

  Heavily laden with grain, sugar, pulp, lumber, fuel oil, gas, and general cargo, the merchant fleet, with many old coal burners, was not expected to exceed seven and a half knots, but Gretton was confident that, pace adverse seas and unkindly U-boats, the convoy would reach the U.K. by its due date, the 25th. The first night of passage was spent in thick fog, and when a large iceberg was encountered, Vidette positioned herself, fully illuminated and whistle blowing, between it and the advancing columns. That danger past, the rest of the night was spent making steady revolutions on course 081°. With daybreak on the 16th the veil of fog lifted and the columns moved smartly ahead at eight knots. Sunflower joined at 1100. Good clear sailing weather continued on the 17th, and five RCAF Fortresses patrolled the surrounding water, though Gretton complained: “The air escort from Newfoundland are not yet trained to convoy work. Their communications are bad and they do not fully understand homing procedure.”46 He particularly regretted that the only day SC.130 was without air cover was the next day, the 18th, when the convoy was sighted by the enemy.

  At 2219, in 54°39'N, 36°47'W, rescue ship Zamalek, which was equipped with FH3 HF/DF, reported a ground-wave signal to the north. Beginning at 0116 on the 19th the air filled with HF/DF contacts—Duncan was fitted with FH4 and Tay with FH3—and cross-cuts revealed the presence of four U-boats, one close on each bow of the convoy and one on each quarter. Taking the role of hunter, Duncan went after the boat judged to be four miles on the port bow. A radar contact was obtained at 5,000 yards, but the boat dived before being seen on the bright, full-moonlit sea. Duncan fired a five-charge pattern in the estimated diving position and started operation “Observant.”47 Though without visible result, this first attack, which kept a U-boat down and out of the game, was representative of the aggressive behavior the B7 escorts displayed thereafter over the next forty-eight hours against an enemy force numbering altogether thirty-three U-boats, though apparently no more than twenty would be in contact with the convoy.

  The force was organized by BdU as the result of an intercepted signal in Allied Convoy Cipher No. 3 dated 15 May, which B-Dienst forwarded on the 17th. The signal gave SC.130's position, course, and speed, as well as the identity of its close escort, B7.48 Here was an opportunity for BdU to gain vengeance for die Katastrophe am ONS.5. Accordingly, two patrol lines were established to be in position at 2000 on the 18th athwart the convoy’s course: Donau I, consisting of thirteen boats (two, U-640 and U-657, had been sunk, unknown to BdU) from AK 4258 (56°03'N, 37°55'W) to AK 8141 (53°31, 35°25'W); and Donau II, consisting of twelve boats from AK 4944 (53°09'N, 35°15'W) to AK 8734 (5o°33’N, 33°35'W). In addition, eight boats coming out from Biscay bases or from at-sea refueling were to take up a patrol line from ED 2181 (5o°21'N, 33°25'W) to DD 2769 (48°39'N, 32°35'W) under the name Oder (the river). Although BdU’s orders creating these dispositions were not decrypted by the Allies until the 19th through the 22nd, according to the Bletchley Park Hut 8 record, thus providing no cryptographic intelligence on the basis of which to divert the convoy from danger, the prescient Rodger Winn in OIC’s Tracking Room somehow knew of these dispositions anyway, since on the 17th he wrote in his Special Intelligence Summary:

  The next development will be the establishment of new patrols on an arc between 020° and 140° from Virgin Rocks at a radius of 600 miles from Gander, Newfoundland. Twenty or more U/boats are now moving to take these up and the apparent gap through which SC 130 has been routed is rapidly closing: it will be touch and go whether this convoy scrapes through.49

  But Gretton’s first warning did not come until 2219 on the 18th, when the rescue ship Zamalek reported HF/DF contact. Later, on reaching port—he knew nothing of B-Dienst’s or of Bletchley Park’s cryptographic penetrations—he wondered aloud how it happened that so large a concentration of U-boats had been assembled without warning to him from the Admiralty’s shore-based HF/DF.50 The answer no doubt was that the patrol lines were formed under orders of radio silence.51 Now, at 0300, just before dawn on the 19th, when he knew that he was being shadowed if not surrounded, Gretton turned the convoy 90° to starboard in order to avoid a dawn submerged attack. The stratagem worked, and when the first VLR Liberator (T/120) arrived from Reykjavik and made two attacks on U—731 (Oblt.z.S. Werner Techand), which was undamaged, the enemy boat was approximately where SC.130 would have been had not the foxing course alteration been made. The course 081° was resumed at 0400.

  Liberator T/120 went on to sight five additional boats in the vicinity, a record six for one sortie.52 With so many boats about, Gretton had to be cheered to know not only that aircraft from Iceland and Northern Ireland would watch over him but that a Support Group was on its way to firm up the surface screen: it was the same First Escort Group that had ridden out to assist B7 in the final hours of the ONS.5 struggle. EGI’s frigates Wear (S.O.),
Spey, and Jed, together with the former U.S.C.G. cutter Sennen (Pelican had to return with engine defects) cleared St. John’s at 1930 on the 16th, and in the late morning of the 19th, while closing the convoy 15 miles off from the starboard quarters, Wear sighted a U-boat on the surface bearing 034° 12 miles. At 1135 the boat, identified later as U-952 (Oblt.z.S. Oskar Curio), was seen to dive. At 1209 the crow’s nest lookout in Jed sighted a second U-boat, which Jed and Sennen would later hunt.

  At 1228 the first boat launched a salvo of four eels that passed between Wear and Jed. Wear then altered course up the torpedo tracks and obtained asdic contact at a range of 1,800 yards. At 1245 she made a Hedgehog attack, but only twelve projectiles fired because a safety ready switch handle retaining spring broke. There were no explosions. What was worse, Wear’s helm jammed hard aport and took an hour to fix. In the meantime, Spey closed, obtained contact, and made three D/C attacks, at 1319, 1335, and 1415. The repaired Wear joined Spey in a fourth, barrage-type attack—sixteen D/Cs fired deep from each ship at six-second intervals—at 1533. No evidence appeared on the surface, but U-952 was extensively damaged at 170 meters depth by the last bombardment, and forced back to base.

  The second U-boat, meanwhile, was visible to Jed’s bridge by 1227 at an estimated range of 8 miles. Observing Jed in pursuit, the boat dived at 1245 when 5 miles intervened. Jed made asdic contact at 1312; moments later, the U-boat unaccountably blew tanks, broached the surface, and dived again. Jed fired a five-charge pattern at 1316, and a D/C from the starboard thrower fell directly into the swirl, after which an oil patch appeared on the surface. Contact was not regained until a weak echo was received at 1324 and Jed reduced speed to 10 knots in order to carry out a Hedgehog attack, which she delivered at 1334. There were no explosions, and subsequent loss of echo led Jed to question the contact.

  While the frigate started an “Observant” around the position of the first attack, the cutter Sennen came on the scene, obtained a contact of her own, and fired a ten-pattern at 1405. The explosion plumes were followed at 1427 by oil and bubbles, then, at 1440, by splintered woodwork and a small red object resembling meat or remains. At 1443 the asdic operator reported strange noises like escaping compressed air, and Jed made a H.H. attack on the noise source, with no explosions, at 1447. Oil continued to rise and by 1515, when the two escorts were ordered to rejoin the convoy if no longer in contact, the oil patch was estimated to be over a quarter of a mile wide. In the latest assessment of this engagement, U-760 (Oblt.z.S. Otto Erich Blum) is thought to have been the target of the first two attacks; she sustained damage to upper-deck containers. The second two attacks were made against U-954 (Kptlt. Odo Loewe), which was destroyed by Sennen’s ten-pattern at 1405.53 There were no survivors from U-954, which was on her first combat patrol, having sortied from Kiel, Germany, on 8 April. Among the dead was twenty-one-year-old Leutnant zur See Peter Dönitz, the Grand Admiral’s younger son.54

  A second U-boat would be sunk in the vicinity of SC.130 that day, though it was not a member of the Donau and Oder groups, and when it was found by Hudson “M” of 269 Sqdn. it was proceeding due west some four degrees latitude north of the convoy’s known position. This was U-273 (Oblt.z.S. Hermann Rossmann), another boat on her first patrol. At 1627 the Hudson pilot dived on the neophyte boat and delivered a four-D/C straddle of the conning tower, No. 3 being observed to enter the water on the starboard side within ten yards of the surfaced hull. Almost immediately afterwards, oil spread from the U-boat’s stern, eventually covering an area 100 feet wide and 600 yards long. U-273 remained on the surface for seven minutes, turning continually to starboard, and fighting back with flak. The Hudson returned fire, scoring hits around the tower and causing panic among the lookouts and gunners.

  Finally, at 1634, the U-boat attempted a dive, from which she would not resurface, though floating wreckage did. Another forty-four men descended to their deaths while Hudson pilot Flying Officer J. N. F. Bell returned to base (and to a postwar career as a British Airways Captain). It was another of the Atlantic war’s fateful exchanges, now almost always unfavorable to the German side.55 More mysterious was the disappearance of U—381 (Kptlt. Graf von Pückler und Limpurg), which had sortied from St.-Nazaire on 31 March and made her last transmission to BdU at 1502 on 9 May from qu AK 7962. Subsequently, she was ordered, with three other boats, to form Group Inn, and later to join Donau I. Whether she did either is not known. On the 21st, BdU, not having received any further signals from the boat, asked her to report her position. When no response was received, U-381 was posted as missing with effect from that date. Her loss has not been matched to any of the attacks made by the surface ships of EGI or B7 or by any of the air escorts.56

  Prior to and following Jed and Sennen’s kill of U—954, indeed throughout the 19th and continuing until dawn on the 20th, SC.130's surface escorts made no fewer than twenty-seven individual attacks on U-boats sighted from the cockpit of an aircraft or from an escort’s crow’s nest or bridge, or detected by HF/DF or radar, and/or tracked underwater by asdic.57 Each sighting or contact was pursued energetically in keeping with Western Approaches’ finding that most U-boats sunk by surface vessels during the year prior to May were destroyed prior to their attacks, not afterward (see chapter 3). As it happened, however, none of B7'S attacks and none further of EGI’s resulted in a kill.

  Duncan and Snowflake were certain, because of the accurate placement of the D/Cs and one Hedgehog explosion seven seconds after the pattern struck the water, that they had destroyed a U-boat in a series of six attacks that they carried out jointly between 0755 and 0918 on the 19th, Duncan getting in what he thought was the fatal blow. But a recent reassessment finds that Snowflake s contact, U-304 (Oblt.z.S. Heinz Koch), was undamaged except for a tank put out of action, and that Duncans contact, a different boat altogether, probably U-636 (Kptlt. Hans Hildebrandt), was undamaged.58 Wear and Spey severely damaged U-952 at 1245 through 1533 on the 19th, as shown above; Spey slightly damaged U-413 (Poel) at 0346 through 0542 on the 20th; and Jed lightly damaged U-91 (Oblt.z.S. Heinz Hungershausen) at 0420 through 0439, also on the 20th.59

  Despite that apparent lack of success in destroying U-boats, the surface escorts achieved a success that, on shore, was more highly valued than U-boat trophies hung on a wardroom wall: they saved every merchant ship in the convoy from harm. They did that, under Commander Gretton’s skillful command, by aggressively running to ground every enemy craft sighted or detected, and by directing the VLR Liberators in the cloud cover overhead to every W/T transmission source. The number of HF/DF contacts was striking even by the usual standard of talkative German radiomen: during the 19th and 20th Duncan counted fifty-one, Tay thirty-one, and Sennen twenty-three.60 As each cross-cut came into his plotting room, Gretton vectored the VLRs to the transmitting boat from their overhead air search patterns, which were called by such code names as “Frog,” “Adder,” and “Viper.” On more occasions than a few, U-boat Commanders were stunned to find that at or before the close of an Ausgang F.T. (outgoing W/T transmission), a Liberator was bearing down on their positions. In his war diary entries for 19 and 20 May, Dönitz/Godt complained about the “continual surprise attacks by land-based aircraft out of low-hanging clouds.”61 Of course, BdU attributed them to radar, but the attacks were instead additional evidence of the importance in the Atlantic war of what the Allies affectionately called Huff-Duff.

  The final U-boat kill of the SC.130 crossing came from the air at the hands of No. 120 Sqdn. out of Reykjavik, whose aircraft made twenty-seven sightings on the 19th and 20th. Two VLRs struck at U—707 (Kptlt. Günter Gretschel), which like U-413 (Poel) had operated against ONS.5: at 1340 on the 19th, P/120 dropped four D/Cs on the surfaced Gretschel boat without inflicting injury, but at 0810 the next day, N/120, sighting the same boat and attacking ten seconds after Gretschel submerged, caused severe damage, forcing that boat to retire from the field. At 0745 on the 20th, U-418 (Oblt.z.S. Gerhard Lange) was injured by four D/Cs dropped by Liberator
“X” of 59 Sqdn. based in Ballykelly, Northern Ireland. The kill was made on the 20th by P/120, whose pilot, Squadron Leader J. R. E. Proctor, lifted off from Reykjavik at 0954 and met SC.130 at 1430 in 55°N, 30°W, where, at Gretton’s direction, he began a series of searches, sighting one U-boat at 1448 that he was not able to attack and another at 1710, Red 15° six miles, that he dived on, dropping four D/Cs and obtaining a straddle on the partially submerged boat. It was U-238 (von Mässenhausen), another ONS.5 boat, which had sunk the American McKeesport twenty-two days before.

  The Liberator’s rear gunner saw the boat’s conning tower lifted out of the water for three seconds by the explosions. When the spray of the plumes subsided, the boat was no longer visible, but an oil patch appeared that during the next thirty minutes spread to about 200 feet in diameter, with an “almost white patch” at its head looking like air bubbles. Ironically, at just one hour and eight minutes after this attack, U-258 was sent a signal by BdU ordering her to return to base and to make frequent transmissions over the next three days for purposes of deception. Von Mässenhausen and his crew would not be able to obey that order.62 Meanwhile, P/120 carried on her patrol, and at 1924 sighted a surfacing U-boat three miles distant. Diving, Squadron Leader Proctor decided to strafe the conning tower with machine-gun fire in an apparent attempt to force the boat back under water so that he could drop a Mk.24 Mine. Six crewmen sighted on the bridge returned his fire and the boat remained on the surface.