Snowflake had a dicier experience, which Gretton called “an unusual slip in the drill.” During the sixth U-boat attack, Snowflake followed a radar contact at 0332 and sighted an approaching boat in the process of diving. When about 200 yards astern of the boat’s swirl, the wheel was suddenly put hard-a-starboard, though no such order had been given. As a result, the U-boat passed on a reciprocal bearing 200 yards down the port side and no D/Cs were fired. Snowflake’s Captain, Lieutenant Harold G. Chesterman, R.N.R., dropped three D/Cs between the U-boat and the convoy as scare tactics. At 0336 he gained an asdic bearing at range 2,000 yards and turned to the attack. As he did so, at 0338, ship’s hydrophone first detected, then lookouts sighted, a torpedo pass 20 yards down the port side.34
This was the only torpedo seen the night of 28th/29th. It was launched by U-532 (Korv. Kapt. Ottoheinrich Junker), but it was not the only eel in the water. Just three minutes before, by periscope, Junker had launched a four-torpedo Fächerschuss (fan shot) from his bow tubes at what he called “the third steamer” in a column, estimated by him at 5,000–6,000 GRT. All the eels missed. The depth of run was three meters, which should have been shallow enough to hit a ship even in ballast. Seven and a half minutes later, Junker would hear end-of-run detonations. Meanwhile, using the two stern tubes that a Type IXC/40 boat commanded, he got off a double launch against Snowflake (only one of which torpedoes was sighted), missing again, as already noted, and hearing end-of-run detonations seven minutes later.
Junker states in his KTB (war diary) that as he placed the escort in his crosshairs, he could see convoy steamers in the background. His six misses in that crowded seascape were perhaps ineptitude, or just bad luck. The fault could not have been inexperience: the thirty-eight-year-old native of Freiburg im Breisgau had commanded U-boats since 1936, though it bears mention that he did not have a single ship to his credit. With U-532 having to reload all tubes, the initiative now passed to Snowflake, which Junker’s periscope displayed steaming toward him at high speed, only 1,200 meters distant. “Alarm!” his KTB records, as U-532 opened flood valves and dived to greater depth—and just in time, as Snowflake dropped a ten-charge pattern over him at 0343. When the noise and turbulence subsided at 0345, Snowflake regained asdic contact. With the recorder marking well, Chesterman came round to port, and at 0351 fired a ten-charge pattern set to 100 and 225 feet. This second attack, Chesterman noted, “is considered to be accurate.” Then, with only “doubtful” asdic contact showing on the recorder, and concerned that he should husband his D/Cs remaining for battles to come, Chesterman shaped course to rejoin the convoy.
Deeper than 225 feet, U—532 was still alive, but wounded. Junker wrote in his KTB:
The entire hull of the boat vibrated violently. Before each depth-charge series we could hear the asdic sound pulses [Ping-tongg! Ping-tongg!]…. We found major damage done to the forward hydroplanes. They ran quite laboriously and made strong knocking noises. They tended to stick in the “hard up” position, but could be freed again. For the time being we are limiting them to “up 15°“…. A large number of manometers, lamps, and electrical equipment have gone out, though without any restrictive effect on the boat’s operation…. Battery array No. 1 was badly cracked, with the result that acid leaked into the bilges…. The magnetic compass broke, which is a nuisance because, unable to use the noisy gyrocompass when in creep, or stalking speed [Schleichfahrt, about 2.5 knots] we have no means for checking the course of the boat…. I don’t want to end up running into the hands of the enemy.
Junker records that he remained submerged, experiencing or hearing various series of D/Cs—five more ten-patterns—“additional series or single drops”—“new depth charge attacks”—“three more series”—as far as 0140 (2340 GMT on the 29th) on 30 April, when he surfaced, the last hours having been spent breathing through potash cartridges because of the 3 percent level of CO2 in the boat. Troubled by intolerable noises inside the boat, he set course back to base. The BdU gave U-532 credit for “two hits” and duly noted the boat’s ordeal: “She was hunted for fifteen hours.” The problem with the fifteen-hour story is that the D/Cs heard by U-532 after Snowflake s two drops were not meant for her but for the U-boat involved in the McKeesport event, described below. The sum of U—532's patrol was: no hits, six misses, and one badly bent boat forced back to base.35
The BdU did not learn of U-532's alleged hits until 2 May. At the time of the night battle it was dismayed that not a single Treffer, or hit, had been scored. In rationalizing the failure, it argued first that the boat’s messages to Berlin were inaccurate. They overestimated the convoy’s speed—certainly that was the case with U-650's initial estimates—and the reports from U-386 and U—378 on the enemy’s position were too far distant from each other to make any sense. Second, atmospheric or magnetic interference apparently was preventing BdU’s operational orders from getting through, since no acknowledgments were coming back, and no messages of any kind were received from the boats during the period from 0300 GST on the 29th to 1200 on the 30th. Third, Force 6 winds, heavy seas, and limited visibility greatly hampered surface operations.36 For the first time in a long while, Admiral Dönitz’s command and control system had been frustrated and bootless on the night of the 28th/29th. But an enterprising individual commander, operating on his own initiative, could break the string.
In the early daylight of the 29th, fulfilling Gretton’s expectation that, unable to overcome B7's night tactics, the U-boats might try submerged attacks in daytime, U—258 (Kptlt. Wilhelm von Mässenhausen) slipped inside and under the convoy formation, where he took a position at periscope depth starboard of the convoy’s No. 4 column. In doing so, he somehow avoided the asdic sweeps by the escorts on day stations as well as by Tay, which was searching astern for damaged or shadowing boats, and by Vidette, which returned to her station at 0725 after searching out 15 miles. It was broad daylight. At exactly 0729 1/2, the furtive U—258 scored a hit on the 6,198-GRT American Moore-McCormack freighter McKeesport, ship No. 42, the second ship in No. 4 column, which was on a return voyage from having delivered to Manchester, England, a cargo of grain, steel tanks, foodstuffs, and chemicals.37
Gretton was asleep in his sea cabin when the alarm bell rang. Dashing to the bridge, he ordered “Artichoke” at 0730. In this operation the ship in position “S,” astern, closes the torpedoed ship at maximum asdic speed, and ships in the “forward line,” that is, “A,” ahead, “B,” starboard bow, and “L,” port bow, turn immediately outward to a course reciprocal to the course of the convoy and sweep in line abreast at 15 knots or at the maximum asdic sweeping speed of the slowest ship, the wing ships passing just outside the convoy wake, the inner ship(s) between the columns of the convoy, until reaching a line 6,000 yards astern of the position the convoy was in when the ship was torpedoed. All other escorts continue on the course of the convoy.
Five minutes later, Gretton saw a torpedo, which had passed through several columns without a hit, explode at the end of its run on the convoy’s port quarter, indicating an attack from starboard, probably along 180 degrees. The rescue trawler Northern Gem acquired an asdic contact astern of McKeesport and made an attack with three D/Cs. There was no result. And an “Observant” carried out by Duncan proved fruitless. Admiringly, Gretton called U—258’s action “a bold effort,” and, what was more, the attacker got away—for now.38
On board McKeesport the torpedo’s explosion had come as a complete surprise. The Chief Officer, Junior Third Officer, and two seamen-lookouts on the bridge made no periscope sighting. Neither did the U.S. Naval Armed Guard who manned a four-inch gun on the afterdeck. Nor did the seaman-lookout on the fo’c's’le, although on the starboard side he did see a long, dark, round object leap across a trough of the choppy sea, which he thought was a fish. He correctly identified a second torpedo that ran astern, but it was too late to warn about the first. When the warhead detonated with an awesome bang, it not only shook the whole ship; it opened a hole at the collisio
n bulkhead of No. 1 hold, which, like holds 2, 3, and 5, was filled with sand ballast; put the steering apparatus out of order; flooded the forepart up to tween decks; and twisted plates, beams, and hatches. Fire spread through wooden grain fittings, but the inrushing sea put it out.
McKeesport lurched to port, causing the British Baron Graham on that side to consider evasive action. Incredibly, the listing merchantman maintained convoy speed in her station for fifty minutes, until, with her engine room flooding, she started to sink at 0815, and the Master ordered Abandon Ship. Life nets were thrown over the side and the boats were lowered. Unfortunately, the boats became entangled in the nets, and so did some of the men who used them to climb down to rafts. Several seamen fell into the water, one of whom would later die from exposure, the only fatality from McKeesport’s complement. Last to leave were the Master and the crew of the Naval Armed Guard, under command of Ensign Irving H. Smith, U.S.N.R., who gallantly stood by their gun until ordered to leave. The rescue ship Northern Gem came alongside and picked up the survivors: forty-three seamen, one critically injured, and twenty-five naval crew.
While the Master had cast overside his Confidential Books, including his codes, in a weighted container, he had neglected to jettison his ship’s log and charts, on which future rendezvous positions were marked. Accordingly, Northern Gem made an effort to sink McKeesport with her ship’s gun, but the derelict ship remained afloat. It was U.S. Navy Department policy, stated by Secretary of the Navy Frank Knox on 30 March 1942, that “no U.S. Flag merchant ship be permitted to fall into the hands of the enemy.” Since that was the policy and McKeesport could be boarded by a U-boat crew, Gretton ordered Tay to go back and hole the wreck, which she did with depth charges.
The steel shell went down with all her relics of human habitation, including eight decks of playing cards and other games: cribbage, dominoes, checkers, and acey deucy, as well as sports equipment: darts, deck tennis, two pairs of boxing gloves, and one medicine ball; and divertissements: one portable radio, one Victrola, and twelve records. The Master had no complaint about his escorts. The sinking was, he said, “just one of those things.” Tay then pursued a U-boat contact 49 miles astern and did not rejoin B7 until 0600 the next day, the 30th. At 1100 that morning the convoy half-masted colors for the burial at sea of McKeesport’s lone fatality, John A. Anderson, a Swedish national, who had died on board Northern Gem,39
No attack on ONS.5 developed during the night of the 29th/3oth, although HF/DF and asdic contacts led Duncan and Snowflake to drop “scare tactic” charges. The destroyer Oribi, homed from astern by HF/DF, arrived during the night, at 0100, from EG3. In the southwesterly wind and sea she had only been able to make II knots.40 Her HF/DF equipment (Type FH3) lent additional detection ability to the screen. Coastal Command, alerted to ONS.5’s peril on the 28th but delayed by weather conditions at 120 Squadron’s air base at Reykjavik, finally was able to reestablish air contact when a VLR Liberator arrived overhead the convoy at 0645 on the morning of the 30th. Soon afterward, however, owing to a drop in visibility, the aircraft returned to base in Iceland.
The U-boats would remain at bay all that morning, and at 1045, the short-legged Oribi took advantage of the respite to oil from British Lady. Unfortunately, the destroyer, which was unaccustomed to refueling at sea, fouled the oiler’s gear. That fact, plus a new deterioration in the weather that had already been, in Gretton’s words, “astonishing even in the North Atlantic,” made it impossible for other escorts to top up—with ultimately grave consequences for Duncan.41 By 2100 another gale was blowing from ahead, the wave heights were rising steeply, and the escorts were rolling gunwales under.
At 0105, in the first highly visible sign that some of the U-boats had maintained contact during the past forty-one hours, Snowflake acquired a U-boat’s radar signature at 3,300 yards, ran down the bearing, fired a starshell at about 10 o’clock three miles from convoy, sighted the boat at 3,000 yards, fired “near misses” at her with both the four-inch deck gun and 20mm Oerlikon anti-aircraft (AA) guns at maximum depression, and forced it to dive. To discourage it further, Snowflake dropped a D/C on the swirl—which was a hazardous thing to do given the rough sea, which prevented an attacking ship from getting much beyond the blast effect—as Duncan discovered himself when he dropped two on another contact at 2345: with maximum speed up sea only 8 to 9 knots, the D/C pressure waves lifted his stern clean out of the water, opened leaks, and, what was worse, smashed all the gin glasses in the wardroom.42 There were two other “scare tactic” D/C drops that night, and no general attack on the convoy developed.
The morning weather on 1 May was atrocious. By afternoon a Force 10 gale was dead in the convoy’s teeth, preventing all but the most modest progress forward. Convoy speed was 2.7 knots and dropping. In the tempest, columns as well as ships within columns separated from each other. Commodore Brook’s log noted: “Half convoy not under command, hove to and very scattered.”43 Gretton, whose Duncan was hove to with winds pushing alternately against one bow and then the other, marveled that an entire convoy could be brought to virtually stationary condition. On Pink, Lt. Atkinson placed a chair on the raised platform at the fore part of his open bridge and went into half-sleep, rocking with the motion of the corvette. Nearby were a gyro compass and voice pipes to helmsman and navigator. Compass repeaters were on both wings port and starboard. Ahead and several feet below was the asdic hut (or office). Aft and a deck lower was the helmsman. On the port quarter of the bridge was the tall radar hut (office, house). Aft of the bridge were the ship’s mast and funnel. For protection against the cold gale Atkinson wore a heavy sweater, a cloth, not very warm, duffel coat with hood, a Balaclava helmet (knitted wool head sock), naval cap, seaboot stockings, and mitts. Like the rest of the crew, he was the recipient of wool clothing articles knitted by women volunteers in Australia, New Zealand, and Canada, with whom correspondence was exchanged and lifelong friendships forged.44
Aircraft flew over the dispersed merchantmen during the day, including two RAF VLR Liberators from 120 Squadron in Iceland who gave valuable assistance by identifying the positions of stragglers, and by warning of icebergs, growlers, and pack ice starting thirty miles ahead. Less helpful were two U.S. Army B-25 Mitchell bombers from Ivigtut, Greenland, which made no contact whatever with the convoy either by wireless (W/T), voice radio (R/T), or light signals (V/S), although one of them, as Gretton learned later, made an unsuccessful attack on a U-boat some 60 miles to the south; and one of them further helped to confuse BdU by forgetting to switch off its navigation lights: The flashing beacons, which, of course, announced the bomber’s position and course to any U-boat that might be watching, caught the attention of U-381 (Kptlt. Graff Pückler), which at once signaled BdU about an apparent secret weapon. In Berlin, where Grossadmiral Dönitz and Konteradmiral Godt were at this time unusually accommodating of the notion of secret devices, the BdU war diary for 1 May noted: “The [U-351] observed what was probably a new type of location gear. The Commander repeatedly noticed planes approaching at great height and carrying a light like a planet that went on and off.”
What is more interesting to learn from the 1 May diary entries concerning convoy “No. 33” is that BdU decided that with only six of sixteen Star boats reporting contact with the convoy, the rest having failed to gain purchase, with three survivors of those six now submerged to avoid both the weather and the aircraft, and with so little to show for four days’ effort, further pursuit of ONS.5 was not worth the candle. At dusk the longwave antenna array at Calbe, 43 kilometers south of Magdeburg, sent the order, which could be heard by the submerged boats to a depth of 25 meters: break off the operation. BdU’s rationalization of the failure read: “This attack failed only because of the bad weather, not because of the enemy’s defenses.”45 No doubt a different appreciation of the battle was entertained on the bridge of Duncan.
By dawn the next day, the weather had moderated somewhat, and the speed of the convoy was back up to 5 knots. During t
he previous twenty-four hours only 20 miles had been made. Gretton and his escorts took advantage of the settling seas to round up stragglers, of whom there were many, some at a distance of 30 miles from the Commodore. In this B7 and Oribi were helped by a VLR Liberator from the Reykjavik squadron that flew over 1,000 miles to assist in locating ships. Eventually, most of the flock was gathered, except for two parties taken under charge by Pink and Tay some miles astern, and two laggards that peeled off to sail independently. In the forenoon of 2 May, Gretton and Brook began negotiating the first ice pack on their route. Small growlers and floes now became the hazard rather than high seas. Duncan thought this a good time to top up from British Lady, but the oiler’s constant alteration of course to avoid the ice made the maneuver impossible; and by the time ONS.5 was clear of ice the wind and sea were making up again from the west-southwest, frustrating Gretton once more.
In the evening B7's transmitters vectored in the EG3 Support Group destroyers of Home Fleet, H.M.S. Offa, Penn, Panther, and Impulsive, which joined at 2040. Unfortunately, like Oribi, these were all short-legged ships that had expended a good amount of their fuel making rendezvous. Gretton’s Vidette was the only destroyer in the enlarged screen that had been designed for or, as was the case, modified for long-range escort duty. There was a brief awkward moment when Gretton, who was junior in rank to the Support Group senior officer, Captain J. A. McCoy, R.N., in Offa, “made requests of” (gave orders to) his senior in grade; but Gretton found McCoy more than willing to accept the subservient role, and very friendly in his cooperation.
That night McCoy’s ships took up extended screen stations assigned to them by Gretton, which changed from first dark to midnight, from midnight to dawn, and from daybreak to sunset.46 There was no sign of the enemy during the night, and the morning of 3 May was similarly quiet, except that gale-force winds from the southwest continued to howl around the main body of the convoy, which now numbered thirty-two ships together. The close escort and support ships spent the forenoon searching for stragglers.
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