The first RN-destined weapon, however, traveled to the United Kingdom under the guard of only one officer, Acting Group Captain Jeaff Greswell, R.A.F., who had been in the United States on liaison ASW missions to USAAF bases and was asked to escort the Mk.24 on the British liner Empress of Scotland. It was Greswell who had worked with Humphrey de Verde Leigh in developing the Leigh Light, who had formed the first operational L.L. squadron, No. 172, and who, on the night of 4 June 1942, had made the first L.L. damaging attack, on the Italian submarine Luigi Torelli, while attacking the Italian Morosini as well. At a New York dock, Greswell told the writer, he received the weapon from a USN truck heavily guarded by armed sailors, who carried it up the gangway in three separate unmarked boxes, one containing the nose section, one the midsection, and one the tail. Greswell signed off on the USN documents and, after the ship’s Captain had the boxes placed in his ship’s safe, Greswell asked for and received a receipt. Upon the ship’s arrival at Liverpool much the same high-security procedures ensued, and the three boxes were secretly whisked away on a highly guarded RAF lorry. Imagine his surprise, he asked the writer, when, on leave, Greswell received a postal notice from His Majesty’s Customs inquiring why he had failed to declare the importation into the United Kingdom of an airborne homing torpedo for use against U-boats!25
More efficient security attended the first consignment of Mk.24s in number to Northern Ireland on 27 April and to Iceland on 1 May. Originally the weapon was to have been used first against independently operating Japanese submarines in the Pacific, but the British delegation to the Washington Convoy Conference in March had persuaded Admiral King to permit simultaneous use against the U-boats, for which the date 8 May was set, later advanced to 6 May. The greatest secrecy was imposed on USN, Coastal Command, and RN aviation personnel engaged in operational use of the weapon. It was not, for example, to be released except when a U-boat was diving with the conning-tower hatch closed, or when one had already dived (though never beyond two minutes time), so that the nature of the weapon could not be observed. It was not to be used in the presence of any surface ships, both because their propeller sounds might deflect the Mk.24 from its intended target, and because even the crew members of Allied ships without need-to-know clearance were not to observe or learn about the weapon. Nor was the Mk.24 to be used in the Mediterranean or in inshore waters of the Atlantic where it might run ashore. Even the aircrews employing the weapon were not to be told anything about its operation other than the drill required for maintaining, arming, and releasing it, though most crews could figure out Wandering Annie’s scheme. These restrictions were so faithfully observed that the Germans did not learn about the Mk.24 until after the war.
In the newly formed second VLR Liberator Squadron, No. 86 at Aldergrove, Northern Ireland, aircrews found that a VLR could carry two Mk.24s plus four D/Cs, and this became the standard load. The first operational sorties with the homing torpedoes took place on 7 May, but there were no attacks. At this stage, it should be mentioned, tactical doctrine was minimal, and only after some operational experience was it learned that an individual Mk.24 aircraft was advised, upon sighting a U-boat, to dive upon it with D/Cs or strafing fire to force a dive so that the Mk.24 could be employed. Later, in USN attacks by CVE aircraft working in tandem, the F4F4 Wildcat induced the dive and the TBM-1 Avenger dropped the Mk.24. It was on 12 May that the first-ever attacks employing the weapon were made, all in support of Convoy HX.237, which was being hounded by the U-boats of Gruppe Drossel in 46°40'N, 26°20'W. Three Coastal VLRs from 86 Sqdn. at Aldergrove each sighted a Drossel boat and released a Mk.24 after it dived.26 Two FIDOs wandered off from the scent. But the third hit bang on.
Liberator “B” had lifted off at 0344 with Flight Lieutenant John Wright at the controls. Seven and a half hours later, at 1113, while flying cover for HX.237 in showery weather, Wright and his seven-man crew sighted a surfaced U-boat at 46°4o’N, 26°2o’W and initiated an attack. The target was M-456, a Type VIIC boat on her third patrol, having sortied from Brest on 24 April. Her Commander, born at Kiel in 1915, was Kptlt. Max-Martin Teichert, a Knight’s Cross holder who had torpedoed, among numerous other ships, the trophy RN cruiser H.M.S. Edinburgh on 30 April 1942, while the warship was escorting convoy QP.11 on the Murmansk run; the cruiser had to be finished off by a British torpedo. And, more immediately, on 11 May 1943, Teichert had shared with Clausen (U-403) in the sinking of the HX.237 straggler Fort Concord. Now, on 12 May, the Edinburgh was about to be avenged.
Lookouts on U-456 sighted the approach of Wright’s B/86, and Teichert gave a fateful order to dive. With the conning tower going under, and no ships nearby, Wright’s bombardier released a Mk.24 from his bay, and after the torpedo entered the water, B/86 circled while all eyes on board searched the water’s rough surface. Two minutes later, within a half-mile of the diving swirl, a “brownish patch” appeared, about 90 feet in diameter. Shortly afterwards, U-456 resurfaced and proceeded at high speed on a zigzag pattern, firing away at B/86 with her Flak armament. The Liberator returned fire and made a D/C run in, but overshot with a stick of three. With no more D/Cs, Wright called up the surface escort on R/T and two destroyers, Pathfinder and H.M.S. Opportune, raced toward the scene. The Liberator stayed overhead until 1435, when PLE forced it home to base.27
Teichert sent a first distress signal to BdU and nearby boats at 1130, following it up with another at 1151:
AM NOT CLEAR FOR DIVING. QU BD 6646. AIRCRAFT IS KEEPING
CONTACT. URGENTLY REQUEST HELP.28
The source of his problem was made clear in a signal at 1325:
AM STEERING COURSE 300 AT HIGH SPEED. BAD LEAK IN AFTER
COMPARTMENT, NEED HELP URGENTLY.29
The puncture had been made at some point other than at the propeller shafts, since the boat was moving smartly on the surface. From Berlin BdU ordered U—89 (Lohmann) to proceed at maximum speed to Teichert’s assistance, and later detailed U-603 (Oblt.z.S. Rudolf Baltz) and U-190 (Kptlt. Max Wintermeyer) to the same task.30 Teichert may have been heartened to hear the order given to U-89, and he sent out beacon signals for Lohmann to home in on, but it is clear from his message traffic that as time passed, he became more and more anxious about U-89's whereabouts. At 1526 and 1606:
WHERE IS OUR U-BOAT? [FRAGE WO STENT EIGENES BOOT U.D.] …
LEAK WILL HOLD FOR AWHILE YET.31
TO LOHMANN. WHAT IS YOUR POSITION? DO YOU HEAR MY HOMING SIGNAL? MY POSITION IS BD 6569, COURSE 220, SPEED 11.32
Of course, Lohmann’s position was on the seabed, where he no longer heard anything. And soon Teichert would have to fend for his fate alone. At 1640, the destroyer Opportune, bearing down at flank speed, had the conning tower of U—456 in sight from 10 miles distance, and no doubt the U-boat had the larger vessel in sight as well. In that extremity Teichert must have thought that there was but one supreme expedient and that was to test the material integrity of his wounded boat against the depths, for at 1645 Opportune observed the U-boat dive. Did Teichert think the gamble preferable to surrender? We shall never know. The dive became an irreversible plunge into a bourne from which no hand returned, ranks and ratings closed up at Diving Stations forever.
Though Opportune, joined by Pathfinder, searched the scene, which was probably BD 6594, or 46°39'N, 26°54'W, no further sign of the U-boat was observed. The Mk.24, unaided by any other agency, had performed its appointed duty, and just seventeen months after its conception. Sole credit for U-456's destruction is given to Liberator B/86.33 Dönitz/Godt in Berlin, having, like Teichert, no idea what had really happened to U—456, speculated in the BdU war diary for 13 May that she was “probably sunk by a bomb hit on her stern.”34
In addition to the sinking of two of the U-boats attacking HX.237, surface and air escorts succeeded on 12 May in damaging several other boats, which had to move off for repairs. At BdU it must have been clear that Drossel had taken a beating; accordingly, at 0821 on 13 May, those boats that were operational, unless they were in
positions ahead of HX.237, were ordered to abandon that convoy and retire to the southwestward in order to shore up Groups Elbe I and Elbe II, which had been formed from Elbe and Rhein three days before to intercept SC.129. Before they got away, however, the Drossel boats took one more licking. At 0635, Sunderland “G” of 423 RCAF Sqdn., detailed to a dawn patrol over HX.237, sighted a U-boat at 48°35'N, 22°50'W, ten miles distant from the convoy closing its starboard beam. The Queen made a D/C attack on the surfaced boat, without result, then circled over it, exchanging gunfire. Corvette H.M.S. Drumheller observed the aircraft circling low to the water and sped to the scene, bringing her four-inch gun to bear at 0655. The boat dived, and Drumheller, acquiring an asdic echo, fired depth charges. She was soon joined by the frigate Lagan, which made a Hedgehog attack at 0729 that led to two explosions.
Within one minute of the H.H. firing, a large air bubble mushroomed on the surface, followed by smaller bubbles that lasted about ten minutes and then by quantities of diesel oil that eventually formed a patch 600 feet in diameter. Pieces of wood and a rubber eyepiece were recovered by Lagan. Definitely sunk was U—733 (Korv. Kapt. Alfred Mannhardt von Mannstein), which had sortied from La Pallice on 5 May. It was her sixth patrol. There were no survivors.35 Following this action there were a few scattered attacks on sightings by Biter aircraft, but by late morning, with the enemy having disappeared from every quadrant, Biter and EG5 disengaged to the southwest to support SC.129, about a day’s steaming away.36
That convoy’s close escort EG B2 had had a busy time since the afternoon of the nth, when first contact with the enemy was made in 41°N, 33°W, running down HF/DF and radar bearings and dropping D/Cs on various asdic contacts.37 At 1800 that day, two merchant ships, Antigone and Grado, were sunk by U-402 (Korv. Kapt. Siegfried Freiherr von Forstner). Commander Donald Macin tyre, SO on the destroyer H.M.S. Hesperus, became particularly occupied on the night of the 11th/12th, when he made four D/C, two Hedgehog, and one ramming attacks between 0129 and 0232½ against U-223 (Oblt.z.S. Karljung Wächter). The ramming resulted after the harried U-boat was sighted surfacing and Hesperus opened fire with her 4.7-inch gun and Oerlikons, scoring at least three hits. The boat, which was seen first as trimmed down, or decks awash, then became fully surfaced, and some of the crew came up onto the conning-tower bridge, which was now illuminated by the destroyer’s 10-inch signal projector, where some were seen hit by Oerlikon fire and two went overboard (one, a Fireman second class named Zieger, was recovered by U-359 [Oblt.z.S. Heinz Förster] and later handed back to XJ—223).
The boat then turned under full helm 360° and came beam on across the destroyer’s bows. Mindful that he was still ten days’ steaming from home and that he did not want to disable himself with two other U-boats known present, Macintyre decided to administer only a “halfhearted ram.” With engines stopped and proceeding at about 10 knots, Hesperus struck U-223 just abaft her conning tower. Gunfire delivered at the same moment produced a “blinding red” explosion. As Hesperus withdrew, lookouts reported torpedo tracks from another U-boat approaching from astern. The warheads missed. Thinking the rammed U-boat to be in a sinking condition, Macintyre rejoined the screen of SC.129. U-223, in fact, did not sink but, extensively damaged, was forced to return to base, which she reached, after limping through the dangerous Bay of Biscay, on the 24th.38
By daybreak on the 12th, a considerable number of boats were trying to work their way around to the front, with U-186 (Kptlt. Siegfried Hesemann) acting as shadower. Dönitz/Godt urged them onward: DO NOT SLIDE BACK. FORWARD WITH THE HIGHEST SPEED.39 At 1133 Hesperus obtained an HF/DF contact bearing 020°, ahead of the convoy about 15 miles, and shaped course to investigate. At 1205, with speed reduced to 20 knots to allow for an asdic sweep, Macintyre received a strong echo classified “submarine.” Two minutes later, he made a Hedgehog attack, but there were no explosions. Then, 30 seconds later, the U-boat showed its periscope at 50 yards Green 10°, crossing from starboard to port. Macintyre pursued and fired a ten-pattern, followed by a second H.H. salvo at 1219, again without result. Asdic contact was then lost, leading Macintyre to assume that the boat had gone deep. By hydrophone effect, however, he regained the target, at 1215½, and made a deep drop of ten Minol and Amatol D/Cs set to 350 and 500 feet. Eighteen minutes later, just before a planned deeper drop, Hesperus heard a series of explosions. A fourth and last attack with ten D/Cs set to 550 and 700 feet was carried out at 1233½. Then, at 1245, a single “sharp” explosion—probably internal—and “peculiar noises” were heard quite near the destroyer; soon afterwards, wreckage and oil came to the surface. The victim was the shadower U-186, on her second combat patrol.40
During the rest of the afternoon there was heavy HF/DF activity. Between 1530 and 1930 the close escort made six sightings and two attacks. At dusk, the convoy acutely altered course 40° to port on to 343° in order to “throw the U-boats out of position.” A large-scale night attack by the Elbe I and II boats—there were twenty-two remaining after one sunk and two forced back to base with damage—was feared by Macintyre, but to his surprise it did not materialize; one lone attack was turned back by Hesperus and the corvette H.M.S. Clematis. By the morning of the 13th, HF/DF traffic had greatly diminished, and the appearance overhead later in the day of VLR Liberators no doubt added encouragement to EG B2's aggressive ahead-of-convoy patrolling. When BdU received a signal from the Elbe boat U-642 that it had sighted a carrier (Biter) proceeding on a southwest course at high speed, obviously to lend succor to SC.129, BdU concluded, the decision was made in Berlin to call off operations against the convoy on the 14th. Biter joined SC.129 at 1400 on that day, when, because of its threat alone, the U-boats had already been ordered away. Two days later, absent any further contact with the enemy, Biter and EG5 disengaged, and four days later still, the convoy arrived safely in home waters.
While “powerful air escort” was named the principal reason for ordering withdrawal, BdU was equally concerned that during the 12th when twelve boats were in contact with the convoy and no air escort was yet available, the U-boats still failed to achieve results. It could only surmise that with some unknown shipborne detection devices (actually HF/DF and centimetric radar, primarily the former), “the enemy must have picked up all the boats around the convoy with astonishing accuracy.” It observed that “such a rapid detection of the boats has not previously occurred on such a scale.”41 The campaign against HX.237 and SC.129 had sputtered and failed despite excellent intelligence about the convoys’ positions, courses, and alterations, and despite the fact that altogether, about thirty-six U-boats operated against the two convoys.
The plain fact was that the U-boats’ 1939-period technology (excepting certain torpedo advances) was now no match for the 1943-period sophisticated detection equipment, target plotting tactics, and state-of-the-art weaponry of the surface escorts, not to mention the operational research-developed tactics of the air escorts and their new Mark XXIV Mine. Herbert Werner, I.W.O on U-230, complained to the writer that the “May disaster” was owed to the “unconscionable policies of the U-boat Command” that required crews to go to sea that late in the war with “obsolete and inadequate equipment, weapons, and tactics.” The BdU staff, he asserted, “had not prepared for this disaster. It discounted what the Commanders were reporting from the field. It didn’t want to face reality—the inevitable that was to come.”42
While that view may be regarded as extreme by other U-boat veterans of Black May, it is beyond serious dispute that by that month, if not earlier, the U-boat, considered as a high seas detection instrument and weapons platform, was outclassed by the quality of the Allied forces, sea and air (excluding the Swordfish), arrayed against it. The numbers still favored the U-boats, but the disparity in quality was starkly apparent. Add to that the ever-widening gap between the experience and proficiency levels of the human components on either side, and the reasons for what Werner called “the May disaster” were all the more manifest. The material inequalities were reflecte
d in BdU’s bar graphs. Since the pivotal Battle for ONS.5, the exchange rate of U-boats lost for merchant ships sunk suffered an ineluctable, if uneven, decline: In the battle for HX.237 the U-boats had exchanged three U-boats lost for four stragglers sunk; and in the battle for SC.129 they exchanged one boat sunk and two severely damaged for two convoy vessels sunk. In Convoy ONS.7 to follow, the loss ratio would be one-to-one, and, strikingly, that one merchant ship lost to enemy action would be the last lost in the Northern transatlantic convoy lanes for the remainder of May and the whole of June.
On 11 and 12 May BdU collected twenty-five U-boats from those just entering the North Atlantic from French, German, and Norwegian bases, as well as from those that were refueling in midocean from the supply boats U-459, U—U-119, U-461, and U-514, and formed them into five small groups, placed southeast of Greenland, named picturesquely after rivers: Lech, Isar, Inn, Illier, and Nab. Westbound Convoy ONS.7, having departed the U.K. on 7 May under the guard of EG B5, encountered Iller on the 13th when U-640 (Oblt.z.S. Karl-Heinz Nagel) reported sighting its columns in AL 1265. Later on the same day, Groups Inn and Isar were ordered to combine forces in a new patrol line, Group Donau [Danube River] I, and Lech and Nab were similarly joined to form Donau II, both new groups charged with the task of interdicting U-640's convoy. The Iller group, of which U—640 was a part, was ordered to operate independently against ONS.7.
But shadower U-640 herself would not be a factor for long, since, early on the next day, she was caught on the surface at position 6O°32’N, 3I°O5‘W by Catalina “K” of USN 84 Sqdn. based in Iceland. In 7/10th cloud with bases at 1,700 feet and visibility ten miles, K/84 sighted U-640 sixteen miles from the convoy and, at 0739, initiated an attack from the still-surfaced U-boat’s port beam. At 75 feet off the deck the pilot released three USN 350-pound depth bombs (D/Bs) set to shallow 25-foot depth. Nos. 2 and 3 D/Bs straddled the boat, and following their explosions, the “blue-black” hull slowed from 8 to 2 knots, left a path of air bubbles 20 yards wide, became stationary, wallowed, listed at a sharp angle, and sank.43
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