In either event, such high losses of one U-boat (using the low figure of six boats) for every 2.16 (using the actual figure of thirteen merchantmen) or 2.66 (using the claimed figure of sixteen) ships sunk was an attrition rate that could not be borne, and as Donitz stated later, “I regarded this convoy battle as a defeat.”28 More irreplaceable than the boats, and more critical a loss at this period of the war—one remembers the dangerously declining numbers of trained RAF pilots during the Battle of Britain—was the death toll of U-boat ranks and ratings: a total of 364 human casualties.
Also telling, apart from the number of U-boats sunk, was the number of boats damaged by escort action: Seven boats were so severely impaired they were forced back to base: U-386, U—528, U—332 (in the first stage of the battle, 28 April-1 May), U-648, U-732, U-358, and U-270 (in the second stage, 4–6 May). As noted earlier, boats forced home were the tactical equivalents of kills in a convoy battle. Eleven other boats were roughly handled, suffering heavy to light damage: U-413, U-314, U-648, U-438, U-226, U-223, U-533, U-634, U-266, U—267, and U-575. These boats were removed from the scene for a time, either long or short, while they undertook repairs, and thus were not available during those intervals for operations. (Since Professor Blackett considered four boats damaged to be the equivalent of one boat sunk, by that measure 4.5 boats could be added to the tally of those sunk.) Also notable in the defense of ONS.5 were the twenty-odd occasions when U-boats were driven off or forced to dive; submerged, it bears repeating, they were greatly retarded in their ability to make nighttime attacks. And mention should be made of several boats, such as U-552 (Kptlt. Klaus Popp), that were forced to retire by reason of fuel depletion.
Finally, the records disclose a failing that was endemic to the U-boats in this period and for some time prior: most were not pressing their strength in numbers and most were not taking their shots. Although Fink boats made approximately forty attacks, the vaunted BdU wireless control system seems never to have directed more than fifteen boats at a time into close contact with the convoy, the usual number brought to bear being no higher than nine. In the late forenoon of the 5th, BdU had expostulated: there are forty of you. And the boats in contact correctly reported the convoy’s position and base course all through the battle, as Enigma intercepts disclose. What was the problem? Was it perhaps the low level of command experience, previously noted, that inhibited the effective maneuver and attack of certain boats? Or did low fuel levels in many boats perhaps induce a caution that led those Commanders “to lose the name of action?” Or did the aggressive behavior of the escort screen, which punched as often as it counterpunched, simply succeed tactically in holding the majority of boats at bay? The textual record would support all three possibilities.
In W/T transmissions to Berlin on 5/6/7 May, a significant percentage of the boats reported large numbers of unexpended torpedoes. It is not unusual to read, for example, in the traffic from U-223 and U-378 on 5 May: 12 e torpedoes, 2 a torpedoes, their full complement for a VIIC boat; or in that from U-514 on 6 May: all torpedoes, or in that from U—231 on 6 May: all eels. (This was a longtime besetting weakness of the U-boat force, of which only a little more than 50 percent of boats actually engaged in combat operations sank or damaged an Allied vessel during the war.)29 That so large a concentration of boats, deployed in such favorable position, should have come up short in torpedo launches must have cast a pall of doubt over BdU planning for future operations.
Fog was not alone to blame for the defeat. Dönitz and Godt stated, “The operation against Convoy No. 36 also had to be broken off because of enemy radar.” It was obvious that in low-visibility conditions the convoy escorts had been able to readily locate the positions of surfaced U-boats, and without the boats learning of their exposure by means of the standard Metox search receivers. The surface escorts, and aircraft, too, it was reasoned, must be equipped with some new kind of detection equipment. Finding an answer to this problem was of “decisive importance” for submarine warfare. “To sum up,” they wrote on 6 May:
Radar location by air and naval forces not only renders the actual attack by individual boats most difficult, but also provides the enemy with a means of fixing the stations manned by the submarines and of avoiding them, and he obviously makes good use of this method. Radar location is thus robbing the submarine of her most important characteristic—ability to remain undetected. All responsible departments are working at high pressure on the problem of again providing the submarine with gear capable of establishing whether the enemy is using radar; they are also concentrating on camouflage for the submarine against [radar] location, which must be considered the ultimate goal.30
Dönitz’s son-in-law Günter Hessler, who served on Godt’s operations staff, wrote after the war that staff thinking at the time was that the Allies were using either a radar wavelength beyond the capacity of the Metox to detect (which was correct) or a nonradar device such as infrared rays. He expressed the dismay of the staff that in the just-completed operation, “surface escorts alone had sufficed to inflict grave losses on an exceptionally strong concentration of attackers.” Where the Allies spoke of the “U-boat menace,” the Germans now spoke of the “radar menace.” Unless that menace could be quickly and effectively countered, Hessler said, the position of the U-Bootwaffe would become “desperate.”31
In his Memoirs, Dönitz, too, stated that in further convoy operations conducted in poor-visibility conditions, which were a common occurrence in the North Atlantic, the U-boats would be helpless. The Allies’ radar advances, furthermore, would enable convoys to take effective evasive action.32 And radar was not the only technical problem the Germans had to face at this juncture. Hessler informs us that there was consternation expressed after Convoy No. 36 about the fact that British warships were now equipped with powerful new deep-plunging D/Cs as well as with Hedgehogs, about which BdU had learned earlier from decryption, agents, and practical experience. The panoply of weapons arrayed against the U-boats was increasingly sophisticated and effective, particularly since new tactical refinements to “under-water location,” or asdic, had made possible accurate depth charge pursuits on days and at times “when there was fog.”33
In their 6 May appreciation Dönitz and Godt also took serious notice of the danger posed to U-boat patrol lines by Allied air escorts, which had “always forced our submarines to lag hopelessly behind” convoys and had prevented them from scoring hits, “especially when naval [surface] and air escorts cooperated efficiently.” They predicted correctly that “the only remaining [air] gaps will be closed within a reasonable length of time by land-based planes, or at any rate by using auxiliary aircraft carriers.” Finally, the Dönitz/Godt wash-up deplored the fact that except for the Pi 2 magnetic influence pistol and a few other minor innovations, “as yet we possess no really effective weapon.” This was a stunning concession. They concluded: “The submarine’s struggle is now harder than ever, but all departments are working full out to assist the boats in their task and to equip them with better weapons.”34
They gave no hint, at least here, that they feared insecure W/T communications; although, in fact, Allied cryptographic sources played no role in the defense against Fink, and most naval Enigma from 5/6 May was not decrypted until the 9th. They made no mention, either, of HF/DF, which, despite ample cryptographic and operational evidence, both BdU and Naval Intelligence analysts continued to believe was limited to shore-based installations. Refusal to admit the possibility of shipand aircraft-borne HF/DF had yielded substantial tactical advantage to the Allies, and would continue to do so.35 Nor did they mention that their long-established principle of concentrating the largest possible number of boats on an individual convoy—in this case nearly one-half of the whole Atlantic force—rather than make fewer attacks on a greater number of contacts had let six other convoys pass unmolested, and had immobilized the attacking force for a week afterward, during which time boats had to be refueled or replaced.
Nor was there any
mention in the BdU war diary, or in Hessler’s recollections of the BdU mind in early May, of a decline in crew morale and confidence resulting from recent reversals. As shown in the prologue, this was a recurring subject of speculation in the OIC Tracking Room in London, where, at least since 19 April, Rodger Winn had observed in W/T traffic what he thought was an increasing anxiety among Commanders.
So far, by the close of 6 May, the beleaguered circle held. Surviving U-boats in the mid-Atlantic regrouped to fight another day, and another night. As the deadly duel continued, there was no question of the fighting spirit exhibited on either side.
While they had no way of knowing about BdU’s order of 1140 halting offensive action, no doubt the B7 and EGi escorts were aware during the late forenoon and early afternoon hours of the 6th that an eerie peace had drifted out from the enveloping fog. There had been no known German torpedo attack against a merchant ship or escort since 0527, when U-192 (Happe) launched a brace of stern tube eels at Loosestrife. The U-boats were still about, as Pelican, Sennen, and Spey had proved, detecting three on the surface between 0551 and 1244, but there had been no observations of periscope wakes or torpedo tracks, which one might have expected on the daylit sea, even in its gauzy cover. Most of the boats appeared to be lying doggo below, outside of asdic range. By an ironic twist, which most hands probably noted, during the preceding night it was the U-boats that had become the quarry, and the escorts the hunter. Perhaps no one was more elated to receive that understanding than Commodore Brook, on Rena, who entered a condensed account of “this big Convoy Battle” in his final report, and set down the score as he learned it from Tay.36
What was left to do, besides mopping up attacks by Sennen at 1244 and by Jed, which would make the final D/C attack on a probable U-boat contact at 2357 that night, was the collecting of merchant ships that had become scattered in the black and the fog, and the refueling of Vidette from British Lady beginning at 1130.37 That completed, the convoy proceeded without incident toward the Western Ocean Meeting Point (WESTOMP) at 48°11‘N, 45°39'W, east of St. John’s, where Canadian warships out of Newfoundland were scheduled to relieve the ocean escort. At 1500, Sherwood’s Mid-Ocean Escort Group B7 and Brewer’s First Support Group were joined by the Canadian Western Local Escort Force (WLEF), W-4. They were four corvettes, by name: H.M.C.S. Barrie (SO), Galt, Buctouche, and Cowichan,38 All the assembled forces together with the convoy columns continued toward WESTOMP, the Navy and Merchant Navy crews of B7 and ONS.5 now having every reason to sense the approaching end of a near three-week ordeal, during which they reached and surpassed the human equivalent of PLE. Their stained, worn ships, having survived both the lash of a stern, impartial sea and the bitterest convoy battle of two world wars, rose and dipped with a sober gravity.
Behind their weary screws flowed runnels of gray and white Grand Banks wash. Beneath their keels the Atlantic shoaled on the continental shelf. The long billows of the central ocean gave way to a shorter and choppy surface, while on either beam squadrons of gulls parked on the water to announce the impending shore. What was best, we may believe, the scent of victory was in the air. No one yet could let down his guard, and none could forget merchant mariners left behind in the deep transepts of the cathedral sea, but a lightened mood understandably took hold among all ranks and ratings, whether under the white ensign or the red duster. There was occasion now for the concertina, the George Formby song, dominoes, “uckers” (ludo), or cribbage. And a long unburdening sigh.
Game, set, and match: U.K.
That night, at 2357, Pelican received a signal from CinCWA directing her, Wear, and Jed to part company from the convoy at daylight on the 7th, if convoy considered no longer threatened, and to proceed at economical speed astern of the convoy to search for torpedoed ships that might still be afloat. They would find no derelicts, but on the forenoon of the 8th, in thick fog, they sighted wreckage and empty lifeboats. After several course changes to support convoys ON.181 and ONS.6, as directed by CinCWA, the three support ship vessels returned through heavy broken pack ice to St. John’s, arriving on the 12th.39 At 1650 on the 7th, on orders from Tay, Vidette and Loosestrife disengaged from the convoy to escort three vessels to St. John’s: British Lady, Empire Gazelle, and Berkel (the last of which had survived the collision with Bornholm on 25 April). They arrived on the forenoon of the 9th. The remaining ships of By, Tay, Snowflake, and Sunflower, parted company for St. John’s on the same day, arriving on the 8th. Pink with her straggler party made the same port on the 9th. As for the main body of ONS.5, destined for Halifax, Boston, and New York, Commodore Brook’s final report read simply (in local time):
May 12th
0520 Detached NY and Boston groups with 3 Corvettes escorting.
1100 Formed single line ahead.
1200 Proceeding up Swept Channel Halifax.
1300 Approaching Pilot Station. Convoy completed.40
It was twenty days since the departure from Oversay. A few individual stragglers made port in the days that followed.
On shore, the By, EG3, and First Support Group Captains typed up their proceedings and after-action reports. Several of them offered, in addition, their reflections on such topics as convoy routes, the performance of personnel, the endurance of escort vessels, the usefulness of weaponiy and equipment, and U-boat tactics. A preliminary summary of certain of these comments was prepared on 9 May by Flag Officer Newfoundland Force (Commodore H. E. Reid, R.C.N.) for ciphered transmission to Commander-in-Chief North West Atlantic (CinCNA), Rear Admiral L. W. Murray, R.C.N., in Halifax. The summary began with the observation that the convoy battle had been divided into two periods, 28 April to 1 May and 4 May to 6 May, with a three-day gale in between. After noting that scare tactics based on HF/DF bearings had proved successful, the summary continued:
U-boats were attacking by night in pairs and threes. Possibly 1 day attack delivered by pair. No new tactics in night attacks. By day, U-boats approached from ahead of centre of convoy and fired from between the columns. U-boats were using 2 different H/F frequencies simultaneously during the night of 4th May. Possibly 2 different packs attacked. A.C.I. [Atlantic Convoy Instructions] diagrams and orders used throughout. Experience shows that at night 6 ships is minimum number on [Type] 271 [radar] close screen unless weather permits 1 side of screen to be left unprotected and that 271 fitted ships of Support Group should be stationed at least 8 miles clear of convoy. Cooperation between Escort and Support Group excellent. Little air cover available due to weather which also prevented fuelling of escorts. Tanker “British Lady” did not carry enough fuel. Rescue trawlers proved their use. It is strongly suggested that convoy was routed too far north into ice and bad weather. Only on 1 night after gale had scattered convoy and in rough sea did U-boats gain upper hand. It is thought likely that day attacks will become more and night attacks less frequent as result of this battle.41
Among the individual ship reports, Tay commented: “All ships worked hard, capably, and with intelligence and considerable humour, and the situation was always well in hand.”42 And again: “All ships showed dash and initiative. No ship required to be told what to do and signals were distinguished both by their brevity and their wit.” Sunflower stated that his asdic team were “most keen and efficient at all times,” and that his D/C team were a close second. The radar operators, with one exception, had no prior sea experience; they compensated for that somewhat by their zeal. The Chief Bos’n's mate and the Coxs’n had shown exceptional leadership in keeping ship’s company, many of whom were at sea for the first time, up to the best service traditions.43
Snowflake observed that the four-inch H.E. was effective in forcing a U-boat to dive when radar reported a boat dead ahead and the gun was trained with sights set to zero: “This obviated the necessity of a long chase.” (The corvette, it is remembered, was slower than the U-boat on the surface.) During a concentrated attack by U-boats, Snowflake recommended, priority should be given to the speed rather than to the accuracy of the coun
terattack, so that the escort could retake position on the screen in the shortest possible time.44
Destroyers Penn and Panther of EG3, which had been with the convoy for fewer than two days (2–4 May) because of fuel depletion, weighed in with comments about their short-legged craft, Penn suggesting that support group operations should be so arranged that destroyers heavy on oil fuel were not sent long distances from base, “as their first need on meeting a convoy is a large amount of fuel,” and bad weather often made refueling impossible.45 Panther suggested “that Sloops and Frigates (who are not constantly faced with fuel problem) ought to make up support groups, and that destroyers should always form part of a definite escort group”—a suggestion fully concurred with by CinCNA, Rear Admiral Murray at Halifax.46 For his part, Convoy Commodore Brook praised “the splendid work throughout on part of Escorts, not forgetting (SO) HMS ‘DUNCAN’ who unfortunately had to leave Convoy short of fuel just before Convoy Battle materialized.”47 Senior Officer Peter Gretton was all too conscious of his misfortune as he talked in St. John’s with the B7 captains and read their reports. That misfortune being that he had missed out on the events of 5/6 May, which were, he said, “probably the most stirring of convoy history.” By a combination of “skill, luck, initiative, and sheer guts,” his B7 group, helped by EG3 and First Support Group, had brought off one of the epic victories in the story of sea warfare. Twenty-one years later he would still be tending to his “wounded vanity,” writing: “I shall never cease to regret that I did not risk the weather and stay with them until the end.… The weather did improve and I would probably have been able to fuel.… I had missed the ‘golden moment’ which comes but once in a lifetime.”48
Yet Gretton’s wounded vanity should have been assuaged by the commendations that came to him on every side for having trained so capable a force as B7, which, as Tay’s report noted, needed no further instructions on what to do when the hour of maximum danger arrived. Rear Admiral Murray was unstinting in his praise: “The absence of the Senior Officer of By on the big night, while unfortunate and inevitable, nonetheless speaks volumes for the training he is responsible for in this outstanding Group.”49 Admiral Horton himself commented that it was “a credit to the training of the group that in his [Gretton’s] absence it was so ably led by his second in command, Lt.-Cmdr. R.E. Sherwood, R.N.R., H.M.S. TAY.”50
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