by Clay Blair
• Improved search radar for U-boats, including sets modified from the Luftwaffe’s somewhat primitive meter-wavelength airborne Hohentwiel.
• A convoy contact buoy. This device enabled the convoy shadower to mark the path of the convoy for the other boats assembling for the attack, even if submerged. After being launched, the buoy intermittently fired off red, green, or yellow star shells, or combinations thereof that imparted certain prearranged tracking information to the other boats.
• Radar deceivers known as Aphrodite and Thetis. Fitted with metal reflectors, these devices were designed (like Allied chaff) to confuse enemy radar operators at night and lead them to think the reflector was the U-boat, giving the boat time to escape. Aphrodite was mounted on a balloon and wafted along just above the water. Thetis was “moored” on the water’s surface by means of ballasting gear.
For the future, German electronic engineers were to produce all-frequency radar “jamming gear,” small enough to fit in a Type VII. Technicians at I. G. Farben were convinced that a radar-absorbing material and/or some other porous materials (Schwaemme) under study would make U-boats invisible to radar, an R&D stealth project dubbed “the black submarine.”
The Germans had also conceived a devilish weapons system known as a “flak trap,” or “flak U-boat” The veteran VII U-441 was the first. She was fitted with two shielded, quadruple 20mm cannons (quad 20s) on bandstands fore and aft of the conning tower, a rapid-fire 37mm on a second, lower bandstand aft, plus nests of machine guns on the bridge. Her task was to escort U-boats across the Bay of Biscay and U-tankers in more distant waters and to sucker unsuspecting Allied aircraft into an attack. Seven other VIIs were likewise converted, but only one other, U-621, sailed as such that summer.*
As for new tactics, the most important was put into effect on May 1. All U-boats that already had discountable single or twin 20mm cannons on the bridge were to remain on the surface and “fight it out” when attacked by enemy aircraft. Meanwhile, the Kriegsmarine had rushed production of the quad 20s and a new 37mm Skoda rapid-fire antiaircraft gun for U-boats, which Hitler favored.
At this same time, on May 5, due to heavy losses, Dönitz directed U-boat Control to withdraw all Type IXs from groups on anticonvoy operations in the North Atlantic. Older IXs in France were only to patrol distant waters where it was thought that ASW measures were less intense. New IXs outbound from Germany to join the Atlantic force were to exercise extreme caution until clear of the North Atlantic area and to attack enemy ships only if conditions were entirely favorable.
U-BOAT LOSSES AND ABORTS
U-boat Control sailed forty-six attack boats against Allied convoys in the North and Middle Atlantic in May: forty VIIs,† four IXs, one VIID minelayer, U-214, and one XB minelayer, U-118* These boats joined or attempted to join boats that sailed in April and were still at sea. Eighteen of the forty-six boats sailing in May (40 percent) did not return.
The U-tanker fleet was still inadequate-to replenish so many VIIs. Of the seven XIV tankers then in service, one (U-460) was supporting a foray to the distant South Atlantic, and two (JJ-459, U-461) were at sea backing up the April boats. One (U-487) was inbound to France from the North Atlantic and one (U-462) was in port for refit. Therefore only two Type XIVs were available to sail in May: the U-463, which left France on May 8, and the new U-488, commanded by Erwin Bartke, age thirty-four, which left Kiel May 18. Allied aircraft were to sink U-463 and as one consequence, Control had to divert three of the four Type IXs that sailed in May (U-170, U-530, U-535 as well as the XB minelayer U-118, to duty as provisional tankers.
Many historians of the U-boat war were to write that by the summer of 1943, most U-boats were commanded by very young and inexperienced officers. Doubtless this view derived partly from an ill-considered and exaggerated statement by Dönitz, cited by the German naval historian Michael Salewski, to the effect that in the later years of the war German submariners “were little more than children.” However, recent age studies have refuted that assertion,† German submariners in 1943 were no younger than they were in the earlier years of the war. There were very few skippers under the age of twenty-five,
The boats sailing to the North Atlantic in May were armed with three types of production torpedoes. The Type VII boats, no longer fitted with topside storage canisters, had twelve torpedoes belowdecks: six electric (G7e) T-3 Faulkes (“homing”) and four air (G7a) FAT I (“looping”) in the bow compartment for night surface attacks, and two electric (G7e) FAT II (“looping and circling”) in the stern compartment for daylight submerged attacks. The Type IX boats, also stripped of topside canisters, had fourteen torpedoes belowdecks: six electric T-3 and four air FAT I in the bow compartment and two air FAT I and two electric FAT II in the stern compartment.‡
The onboard maintenance and the firing of this array of torpedoes had become quite complex. The majority of torpedoes carried were battery-powered “electrics.” These were slow moving and, if the batteries were not kept properly heated, slower still. Owing to the need for extended “patrol lines” to find convoys, fewer and fewer boats actually shot torpedoes, so the jam-packed bow compartment remained an inhospitable living space. When preparing to shoot a FAT I or FAT II, the boats in a group had to radio a “FAT warning” to other boats at or near the convoy fifteen minutes in advance so they could get out of the way or submerge to at least 164 feet. One, two, or more simultaneous or nearly so “FAT warnings” could easily confuse or foul a group attack.
All boats sailing in May confronted the intensified Coastal Command hunter-killer Operation in the Bay of Biscay, Derange. Conceived by Air Marshal John Slessor and Geoffrey Bromet, chief of Coastal Command’s 19 Group based in southern England, this powerful air offensive took place from April 13 to June 6. Although the British air commanders sorely missed the B-24s of U.S. Army Air Forces ASW Squadrons 1 and 2 (transferred to Morocco), they were not without improved resources:
• A new model Leigh Light-equipped Wellington, fitted with more powerful Hercules engines and featherable propellers, which enabled the plane to fly on one engine in emergencies. Importantly, these aircraft were also fitted with the latest AS V III centimetric radar with a PPI display.
Two Coastal Command squadrons, consisting of about fifteen aircraft each, got these new Wellingtons: British Squadron 172 and Canadian Squadron 407. The primary task of the Leigh Light-equipped Wellingtons was to saturate the Bay of Biscay at night, forcing as many U-boats as possible to dive and run submerged and then to surface in daylight hours to charge batteries. By this tactic Slessor and Bromet were able to increase the effectiveness of the Derange daylight air patrols of the Whitleys, Sunderlands, Catalinas, and other aircraft fitted with less sophisticated radar, whose crews relied heavily on daytime visual spottings. Of course, a nighttime kill by a Leigh Light-equipped Wellington was an added bonus.
• Two Coastal Command squadrons, each consisting of about fifteen four-engine Halifax aircraft, also fitted with ASV III centimetric-wavelength radar with PPI display. These were British Squadron 58 (only recently upgraded from older model Wellingtons) and British Squadron 502 (upgraded earlier from Whitleys).
• One Coastal Command squadron of about fifteen B-24s, also fitted with AS V III centimetric-wavelength radar with PPI display. This was British Squadron 224, based at Beaulieu near St. Eval in southwest England. Theretofore the B-24s had been utilized in defensive roles as convoy escorts far out in the Atlantic. The crews welcomed the switch to a predominantly offensive role.
Altogether then, Slessor and Bromet had five squadrons consisting of seventy to seventy-five modern two- and four-engine aircraft fitted with centimetric radar with PPI display for Derange. In addition, in 19 Group there were available three squadrons of Sunderlands (RAF 228, Australian 10 and 461), one squadron of British Catalinas (210), and two squadrons of British Whitleys (612 and OTU 10). These planes were variously equipped with improved Torpex depth charges, Fidos, ASW bombs, and rockets.
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even May boats were sunk or forced to abort shortly after sailing and did not reach operational areas. Five sinkings:
• The VII U-663, commanded by Heinrich Schmid, age twenty-seven, who sailed from France on his third patrol on May 5. Two days later, in the Bay of Biscay, Geoffrey G. Rossiter of Australian Squadron 10, piloting a four-engine Sunderland on Derange patrol, spotted U-663 on the surface and straddled her with six 250-pound depth charges. Nothing further was ever heard from this boat.*
• The XIV tanker U-463, commanded by Leo Wolfbauer, age forty-seven, who sailed on his fifth patrol from France on May 8. A week later, on May 15, a Halifax of British Squadron 58, piloted by Anthony J. W. Birch, spotted U-463 on the western edge of the Bay of Biscay. Birch attacked with six 250-pound depth charges, sinking U-463 with no survivors. The loss of this valuable U-tanker, on top of the accidental sinking of the new XIV tanker U-490 during workup in the Baltic and other losses and mishaps, was to lead to acute complications in U-boat refueling operations in May as well as June and July.
• The new VII U-308, commanded by Karl Mühlenpfort, age thirty-three, who sailed from Kiel on May 29. Seven days later, as U-308 was rounding the Faeroes to enter the Atlantic, the big new British submarine Truculent, commanded by Robert L. Alexander, probably acting on an Enigma decrypt or other intelligence, found her on the surface. Alexander dived and fired a spread of six torpedoes, some of which hit and blew up U-308. When Truculent surfaced to recover proof of a kill, the crew found, in the words of the British writer Geoffrey R Jones† “a large patch of fuel oil” and “a considerable amount of wreckage, shattered woodwork, watch coats, sea boots, paper and loaves of bread.” There were no survivors.
• The veteran VII U-563, which earlier had spent a year in Germany undergoing battle-damage repairs. Commanded for one Atlantic patrol by Götz von Hart-mann, age twenty-nine, she sailed from France on her second patrol under a new skipper, Gustav Borchardt, age twenty-six. Two days later, on May 31, the commander of Squadron 58, Wilfred E. Oulton, piloting a Halifax, spotted U-563 on the surface and attacked with machine guns and nine depth charges in two runs.
The U-563 appeared to be fatally wounded, but she refused to sink. Moreover, Borchardt shot back at Oulton with flak guns during several strafing runs. A second Halifax of Squadron 58, piloted by Eric L. Hartley, arrived and carried out two nearly identical attacks, dropping nine depth charges, but they fell wide and U-563 still refused to sink. She was finally put down by two Sunderlands, one piloted by William M. French of British Squadron 228 and the other by Maxwell S. Main-prize of Australian Squadron 10. The Allied airmen reported “thirty or forty Germans” in the water from U-563—perhaps living survivors—but a search on the following day by JU-88s carrying life rafts proved futile.
In response to Borchardt’s appeal for help, the inbound, fuel-low U-621, commanded by Max Kruschka, age twenty-four, briefly searched for survivors of U-563 but found none and was herself attacked by a B-24 of British Squadron 224, piloted by an American, Robert V. Sweeny, who toggled twelve depth charges in two runs. These severely damaged U-621 but she reached France on June 3, completing a patrol of forty-three days. Due to the heavy damage, U-621 was selected for conversion to a “flak” boat.
• The veteran but luckless VII U-440, commanded by a new skipper, Werner Schwaff, age twenty-eight, from whom Ritterkreuz holder Peter Cremer had re claimed U-333. Schwaff sailed U-440 from France on May 26. Five days later, on May 31, while on the western edge of the Bay of Biscay, a Sunderland of British Squadron 201, piloted by Douglas M. Gall, saw U-440 on the surface. Gall at tacked in the face of heavy flak from U-440 and dropped four depth charges in a good straddle near the U-boat’s stern. The explosion must have badly holed U-440 aft for her bow raised vertically and she sank stern first. There were no survivors.
The four U-boat losses recounted above, which were credited to British aircraft, were the direct result of Coastal Command’s intense Biscay offensive, Derange. It was believed at the time that a single British Halifax pilot, Wilfred Oulton, commander of British Squadron 58, was responsible for three of the four kills: the XIV tanker U-463 and the VIIs U-563 and U-663. For this achievement, the Admiralty awarded Oulton the DFC and DSO, but in the postwar reappraisal, Oulton’s kills in this outbound group were reduced to one, U-563*
Six boats that sailed in May were forced to abort shortly after leaving port, all by British aircraft. These aborts:
• The VIID (minelayer) U-214, commanded by Günther Reeder, age twenty-seven. He sailed to lay a field of fifteen SMA (moored) mines off Dakar While crossing the Bay of Biscay on May 6, a Whitley of Bomber Command’s OTU 10 on Derange patrol piloted by S. J. Barnett hit the boat with a straddle of depth charges and heavy machine-gun fire, severely wounding Reeder and forcing U-214 to abort. Commanded by a new skipper, Rupprecht Stock, also age twenty-seven, she resailed on May 19 and laid the field at Dakar on June 6. The mines damaged one ship, the 6,500-ton American freighter Santa Maria, which was repaired and eventually returned to service.
• The VII U-405, a former Arctic boat, commanded by Rolf-Heinrich Hop-mann, age thirty-seven. Two days out from France, on May 9, an unidentified Allied aircraft hit U-405. Hopmann repaired some of the damage, but he could not stop a bad oil leak. On May 12, he aborted the patrol, arriving in France on May 21. The boat did not sail again until October.
• Yet another onetime Arctic boat, the VII U-591, commanded by Hans-Jürgen Zetzsche, age twenty-seven. Four days out from France, a Whitley of Bomber Command’s OTU 10, piloted by G. W. Brookes, hit U-591, wounding Zetzsche and a seaman. Unable to carry on, Zetzsche aborted the patrol, arriving in France on May 16. While hospitalized, Zetzsche lost command of U-591, which resailed in June. He did not return to Atlantic combat.
• The Type VII “flak boat” U-441. Commanded by a new skipper, twenty-nine-year-old Götz von Kartmann from U-563, who (confusingly) relieved Klaus Hartmann, age thirty, she sailed from France into the Bay of Biscay on May 22. She carried sixty-seven men, including a doctor, two engineers to test radar-detection gear, and a team of highly trained gunners to man her two quad 20s and the 37mm flak guns.
Three days out, on May 24, a Sunderland of British Squadron 228, piloted by H. J. Debden, spotted U-441, took the bait, and attacked with a salvo of depth charges. Handicapped by the loss of one quad 20, which failed owing to a poor weld in the bandstand, U-441 nonetheless hit and shot down the Sunderland with the loss of all hands. Badly damaged in the bow area by the depth charges, U-441 was forced to abort to France, arriving in Brest on May 26, a voyage of but five days. This inauspicious debut of the first “flak trap” appeared not to have discouraged the Germans; the conversion of the other seven flak boats proceeded apace.
• The IXC U-523, commanded by Werner Pietzsch, age twenty-six, bound for the Americas. She too sailed from France on May 22 and was not far from U-441 on May 24 when the latter was hit. A Whitley of Bomber Command’s OTU 10, piloted by S. C. Chatton, attacked U-523, inflicting such severe damage that Pietzsch was also forced to abort, arriving in Lorient on May 26. The boat did not resail until August.
• The new VII U-450, commanded by Kurt Böhme, age twenty-six, who sailed from Kiel on May 25. Two weeks later, on June 6, a B-17 of British Squadron 220, piloted by H. Warren, attacked U-450 in the Iceland-Faeroes gap. The machine-gun fire and depth charges seriously wounded four men, including Böhme, slightly wounded three others, and wrecked the boat.
In response to U-450’s SOS, U-boat Control authorized Böhme to abandon ship, if necessary, and directed four new VIIs from Kiel and the VII U-592, which had sailed from France with a doctor, to assist. Three of the four new VIIs from Kiel reached U-450 on June 9 and helped with the wounded and with repairs. When it appeared that U-450 could reach port after all, U-boat Control released all boats except the inbound U-645, commanded by Otto Ferro, which escorted U-450 to the rendezvous with the doctor on U-592 on June 13. The doctor swam across to U-450 and treated the wounded, after whic
h U-592 went on her way. From there Otto Ferro in U-645 escorted U-450 into Brest, arriving June 22. Böhme retained command of U-450 but the boat did not resail until mid-October.
These eleven losses or aborts of the outgoing May boats were only one part of the devastation of the Atlantic U-boat force. As has been or will be told, numerous other inbound U-boats were sunk or destroyed in May.
The mounting success of Derange provided John Slessor with the necessary clout to pressure Washington into contributing significantly more aircraft to the Bay of Biscay offensive, specifically for an even more intense campaign planned for the summer months, code-named Musketry followed by Seaslug followed by Percussion. To urge his case, Slessor flew to Washington and met with President Roosevelt, the Secretaries of War and Navy, and the Joint Chiefs of Staff, Generals Marshall and Arnold and Admiral King.
Slessor arrived in Washington at a climactic moment in the prolonged and vastly troubling history of the Army and Navy struggle over control of land-based ASW aircraft. Those services were finally working toward a logical, long overdue—even historic—deal whereby the Army would, in effect, get out of the antisubmarine business worldwide and leave that task exclusively to the Navy. As part of the deal, the Army Air Forces agreed to turn over to the Navy its trained B-24 squadrons, provided King allowed the Army Air Forces to receive an equal number of B-24s from the Navy’s paltry 1943 allotment.* When King agreed to this, a schedule for the gradual swap was drawn with a completion date of September 1, 1943.
The Army Air Forces and Navy’s ASW B-24 squadrons were to be operationally controlled by Tenth Fleet. Thus in order to accomplish his mission of obtaining more American B-24s for the Musketry-Seaslug-Percussion summer offensive in the Bay of Biscay, Slessor had then to coax them out of the fearsome and supposed Anglophobe, Admiral King.