Hitler’s U-Boat War- The Hunted 1942-45

by Clay Blair

  This formidable Allied ASW force in the North Atlantic comprised fifty-seven squadrons of 684 aircraft, not counting Hudsons, Whitleys, and other low-performance aircraft in frontline units. Yet many problems remained. Four different agencies controlled these planes: RAF Coastal Command, the Royal Canadian Air Force, the U.S. Navy, and the U.S. Army Air Forces. Coordination and cooperation between these agencies left much to be desired. The U.S. Navy and U.S. Army ASW air forces were still at sixes and sevens over doctrine and command, studiously and determinedly avoiding a Navy-controlled operational merger somewhat similar to that of RAF Coastal Command. The British and Americans continued to deny the Canadians a fair share of modern ASW aircraft and ASV radar and other electronics.

  By far the most efficient U-boat killers were the B-24 Liberators. By March 1943, the Allies had deployed five squadrons of these killers, comprising sixty-odd planes:

  RAF 120 in Iceland

  RAF 86 in Northern Ireland

  RAF 224 in southern England

  USAAF 1 in Morocco

  USAAF 2 in Morocco

  Eleven other Allied B-24 squadrons, comprising 132-plus aircraft, were fitting out or working up for ASW duty in the Atlantic. Five were U.S. Navy (Bombing Squadrons VB 103, VB 105, VB 110, VB 111, VB 112), four were U.S. Army Air Forces (4, 6, 19, 22), one was British (59), and one was Canadian (10).

  The conferees at the Atlantic Convoy Conference naturally wished to rush into combat these eleven B-24 squadrons that were fitting out or working up. In particular, they believed the most urgent task was to do everything possible to close the Greenland “Air Gap.” However, the B-24s were complicated aircraft and all required substantial modification for ASW. Therefore the eleven squadrons designated to receive B-24s for ASW in the North Atlantic in 1943 deployed only slowly:

  RAF 59 to Northern Ireland 5/43

  USAAF 4 to southern England 7/43

  USAAF 19 to southern England 7/43

  RCAF 10 at Newfoundland 7/43*

  USN VB 103 to southern England 8/43

  USN VB 105 to southern England 9/43

  USN VB 110 to southern England 9/43

  USAAF 6 to southern England 9/43

  USAAF 22 to southern England 9/43

  USN VB111 to Morocco 11/43

  USN VB112 to Morocco 11/43

  When all of these squadrons had been deployed, there were two hundred B-24s on ASW duty in the North Atlantic, 132 of them (66 percent) manned by U.S. Army or Navy crews.

  The U.S. Navy had intended to substantially reinforce its North Atlantic ASW squadrons in 1943 with two new aircraft types. However, one type was a technological failure; the other, like the B-24, entered service all too slowly. These were:

  • The PBM-3 Mariner twin-engine, gull-wing flying boat, in production by the Glenn L. Martin Company. This plane was conceived as a sort of upgraded Catalina. On paper it had much more powerful engines (2,100 h.p. versus 1,200 h.p.), twice the fuel capacity (3,488 versus 1,705 gallons), twice the combat radius (1,200 versus 600 nautical miles), and over three times the pay load (14,600 versus 4,000 pounds).

  By January 1943, Martin had delivered only sixty-four PBM-3s to the U.S. Navy. These had been distributed as follows: twelve to Patrol Squadron VP 32 in the Caribbean; six each to the newly commissioned patrol squadrons in the U.S., VP 201 through VP 208; and four to R&D agencies.

  However, the PBM-3 was plagued by innumerable faults: severe engine weaknesses, poor aerodynamic characteristics, erratic performance of the bombing system, and inadequate spare parts, to name only the most important. Exasperated, the Atlantic Fleet aviation authorities officially recommended (on April 8, 1943) that the contract with Martin be canceled and that the squadrons that had or expected these aircraft be reequipped with PB Y-5 A (amphibian) Catalinas. Admiral King rejected this proposal and directed the naval authorities to drastically modify the PBM-3 so that it could carry out its intended ASW mission. Accordingly, the authorities issued orders to “relieve the overload condition” of this aircraft. They were to eliminate armor, waist guns, ammo, oxygen equipment, bombsight and stabilizer, mattresses, and so on. The first modified aircraft, PBM-3S (stripped), was delivered on June 1, 1943, the second aircraft on July 27.

  An official Navy aviation historian wrote that “the plane as stripped left much to be desired in an efficient Anti-Submarine Warfare type of aircraft.” Therefore naval aviation authorities gave Martin a new contract for yet another new model, the PBM-3D. The first of these was delivered on December 3, 1943. But, the historian continued, “considerable difficulty was experienced with this model as well.”

  So stripped, these aircraft could not be deployed where there was even a slight chance of meeting enemy aircraft. Therefore, as the newly equipped Mariner squadrons were commissioned, most were deployed to patrol the waters of the Gulf of Mexico, Caribbean, and Latin America.*

  • The PV-1 Ventura, a twin-engine, land-based, medium bomber, in production by Lockheed. This plane, a substantially upgraded Lockheed PBO Hudson, the Navy’s version of the U.S. Army Air Forces B-34 medium bomber, had a combat radius of about five hundred nautical miles. Conceived initially for service in the Pacific where strong Japanese fighter opposition was expected, it was also employed over waters in North, Central, and South America, and West Africa in an ASW role.

  The big disappointment—and headache—for the U.S. Navy was the slow—very slow—delivery schedule of the PV-1 Ventura, its first official allocation of land-based bombers. The Army Air Forces retained first priority for acquiring these planes (as B-34s); the Navy a lesser priority. By January 1943, the Navy had in hand fewer than fifty Venturas. As related, with these it reequipped the Newfoundland-based Catalina Patrol Squadrons VP 82 and VP 93, which were redesignated Bomber Squadrons VB 125 and VB 126. As other Venturas slowly came into service, they were assigned to Bomber Squadrons VB 127, VB 128, and so on.†

  THE NORTH ATLANTIC RUN: MARCH 1943

  In the month of March 1943, U-boat Control sailed forty-seven boats against Allied convoy routes in the North and Middle Atlantic. These consisted of thirty-five VIIs‡ eleven old and new IXs, unsuitable for hard convoy battles, and one XB minelayer, U-117. Thirteen of the attack boats were new or commanded by new skippers. Like the sixty-seven boats that sailed in February, all the March boats reached assigned operating areas in spite of Coastal Command’s intensified air offensive in Biscay Bay, which culminated in Operation Enclose I, from March 20 to 28. Assigned to reinforce groups then composed largely of February boats, about half of the March boats participated in the unusual German successes achieved against convoys that month.

  One outbound VII, the U-333, still commanded by Werner Schwaff, very nearly met catastrophe. Two days out from La Pallice on the night of March 5, an unidentified Leigh Light-equipped Wellington of Squadron 172, newly fitted with centimetric-wavelength radar (ASV III), attacked U-333 seemingly out of nowhere. Schwaff’s Metox had given no warning, but his flak guns were manned and the gunners were exceptionally alert. They hit a fuel tank in a wing of the Wellington with incendiary bullets, and it burst into flames. The plane continued its run, dropped four depth charges, then plunged aflame into the sea. Two missiles hit U-333. One bounced overboard to no effect. Another crashed through and lodged in the aft superstructure but failed to detonate, a very lucky break for the Germans.

  Schwaff’s report, combined with similar Metox failure reports about this time from Werner Hartenstein in U-156 near Trinidad and Günther Reeder in U-214 in the Caribbean, led U-boat Control on March 5 to suspect (correctly) that the Allies had a new airborne radar that Metox could not detect. This suspicion was more or less confirmed by the recovery of the H2S centimetric-wavelength radar from a crashed British Stirling near Rotterdam on February 2. Moreover, at about this same time a captured British airman cleverly misled the Germans into believing that Metox itself emitted a strong signal on which Allied airmen could “home” and therefore its use was dangerous.

  The failure of the
Metox FuMB against airborne centimetric-wavelength radar led the Germans to pursue urgent R&D on a new detector and to mount clumsy experimental versions of meter-wavelength search radar on U-boats. However, until these electronic devices were more fully developed and in hand, Dönitz and U-boat Control had no choice other than to beef up the flak arrangements on U-boats and to strongly urge (i.e., order) skippers to remain surfaced and fight off enemy aircraft, especially in the Bay of Biscay where the Leigh Light-equipped Wellingtons patrolled.

  The flak arrangement on all U-boats by March 1943 had been improved. The guns were mounted aft of the conning tower on two separate, open, semicircular platforms, an upper one, and a lower one called the “Winter Garden.” The flak guns on each platform were either single or twin rapid-fire 20mm cannons. The 20mm weapons were not always reliable and did not have much punch. The goal was to put a pair of improved (C/38) twin 20mm guns on the upper platform and a more powerful rapid-fire 37mm gun on the Winter Garden. Until that goal could be realized, various mixes of flak guns were the rule, but no boat had a gun greater in caliber than a 20mm.

  Unless they were unaware and unalert, most U-boats stood a fair chance against the thinly armored, slow, and somewhat ponderous Catalina and Sunderland flying boats and the old and slow Wellingtons and Whitleys. Not so the much faster and more heavily armed B-17s, B-24s, and Halifaxes. The U-boats were highly vulnerable in a fight with these aircraft. They had no armor to protect the relatively thin pressure hulls; the flak guns had no protective splinter shields; the German gunners were completely exposed, and the reloading of ammo was slow at best. Should two aircraft attack the U-boat simultaneously from different angles, the German gunners would be hard-pressed to deal with both. Moreover, owing to the position of the conning tower, it was almost impossible to fire the flak guns from aft to fore, so the skipper had to maneuver the boat in order to obtain a clear field of fire.

  More difficulties for the U-boats lay just ahead. British-built aircraft rockets and the American-built Fido air-dropped homing torpedo were then being distributed to a number of Allied ASW aircraft units. Fido was rightly viewed as a highly promising weapon, especially for “jeep” carrier operations. The tactical doctrine worked out by the navalists was that one or more high-speed Grumman F4F Wildcat fighters (Martlets in the Royal Navy) would attack the surfaced U-boat with six wing-mounted .50-caliber machine guns, wiping out the German flak guns and gunners, thereby forcing the U-boat to dive. Thereupon a loitering Grumman TBF Avenger torpedo bomber would drop a Fido on the swirl.

  As in prior months, there were not nearly enough Type XIV “Milk Cow” U-tankers to support so great a number of Type VIIs in March. Of the six tankers of this class, two, the U-459 and U-460, which returned to France in the first week of March, were undergoing long refits and did not resail until late April. The U-461 and U-462 were at sea refueling February boats and returned to France on March 11 and 22 for refits. The other two XIVs, U-463 and the new U-487* sailed on March 4 and 27, respectively.

  What this meant was that only one XIV tanker, U-463, sailed afresh in the month of March in time to replenish the numerous VIIs at sea. Therefore it was necessary to order the XB minelayer U-117 to serve as a provisional tanker after she laid her minefield.

  Like the February boats, the boats that sailed in March were the beneficiaries of an exceptionally precise flow of convoy information from B-dienst. Oppositely, as related, the Allied codebreakers were unable to break four-rotor naval Enigma consistently during the first ten days of March, and not at all from March 10 to March 19.

  The boats sailing in March also faced hideous winter weather. Herbert Werner, author of Iron Coffins, who departed from Germany in February as first watch officer of the new VII U-230, remembered March this way:

  The sea boiled and foamed and leaped continually under the lash of gales that chased one another across the Atlantic from west to east. U-230 struggled through gurgling whirlpools, up and down mountainous seas; she was pitched into the air by one towering wave and caught by another and buried under tons of water by still another. The cruel winds whipped across the wild surface at speeds up to 150 miles an hour, whistling in the highest treble and snarling in the lowest base.

  When we were on watch, the wind punished us with driving snow, sleet, hail, and frozen spray. It beat against our rubber diver’s suits, cut our faces like a razor, and threatened to tear away our eye masks; only the steel belts around our waists secured us to boat and life. Below, inside the bobbing steel cockleshell, the boat’s violent up-and-down motion drove us to the floorplates and hurled us straight up and threw us around like puppets. And yet we managed to survive the furious wind and water, and to arrive in our designated [grid] square in one piece.

  Acting on information from B-dienst, U-boat Control deployed twenty-three boats in three groups: Wildfang (Madcap), Burggraf, and Neuland south and southeast of Greenland to intercept an eastbound convoy. This was Slow Convoy 121, which sailed from New York on February 24, with eighty merchant ships, plus LSTs. Twenty-one of these ships put into Halifax to await the sailing of the next Slow Convoy. Finally comprised of fifty-nine merchant ships plus the LSTs, the convoy was too thinly guarded by the sole American escort group, A-3, commanded by Paul Heineman. The warships consisted of the Treasury-class Coast Guard cutter Spencer; the old four-stack destroyer Greer; and three corvettes, two Canadian, one British.

  Aware of the U-boat groups from Enigma intercepts, Allied authorities adroitly slipped the convoy between groups Wildfang and Burggraf. However, a recent Arctic transfer, the U-405, commanded by Rolf-Heinrich Hopmann, one of four boats backstopping Wildfang, found the convoy on March 6. Upon receipt of Hopmann’s report, U-boat Control redeployed the twenty-three boats of the three groups and the four backstoppers into two attack groups: Westmark (seventeen boats, including the four backstoppers), and Ostmark (ten boats). Elsewhere on the North Atlantic run, fourteen other boats (six from Wildfang, six from refueling from the tanker U-462, and two from Burggraf) formed a new group, Raubgraf (Robber Baron). Thirteen others, well to the east, rebuilt group Neuland, which had been gutted to form group Ostmark.

  There was a high percentage of green skippers in groups Westmark and Ostmark, assigned to attack Slow Convoy 121. Eighteen of the twenty-seven boats (66 percent) were on maiden patrols from Germany, ten assigned to Westmark and eight to Ostmark. In addition, there were three veteran boats with new skippers, two in Westmark and one in Ostmark. Therefore, twelve of the seventeen boats in Westmark (70 percent) were new or had new skippers and nine of the ten Ostmark boats (90 percent) were new or had new skippers. Only six of the twenty-seven skippers (22 percent) had made one or more prior patrols.

  U-boat Control directed the seventeen boats of Westmark to close on Hopmann’s U-405, attack Slow Convoy 121 immediately, and hold tightly to the formation. The ten boats of Ostmark were to remain east of the opening action and wait for the convoy to come to them. The Westmark boats attempted to comply with these instructions but miserable weather (snow, sleet, hail, gale-force winds) and poor communications thwarted a coordinated attack.

  During the night, six of the seventeen Westmark boats found Slow Convoy 121 or parts of it. The green skipper Paul Siegmann, age twenty-nine, in the new VII U-230, shot at what he described as two 5,000-ton freighters and claimed both sank, but in reality, he put down only the 2,900-ton British freighter Egyptian. The veteran transfer from the Arctic, Hans-Jürgen Zetzsche in U-591, sank the 6,100-ton British freighter Empire Impala, which had humanely but unwisely stopped to rescue survivors of the Egyptian. Two new VIIs, U-448, commanded by Helmut Dauter, age twenty-three, and the experienced U-659, commanded by Hans Stock, age twenty-seven, were forced to break off the chase on account of engine failures and head for the newly sailed tanker, Leo Wolfbauer’s U-463. Neither boat sank a ship on these patrols.

  The weather worsened to nearly hurricane force. Even so, about six boats (four new, two veteran) of the fifteen left in Westmark managed to h
old contact with the core of Slow Convoy 121, which was disorganized by the weather. Over the next forty-eight hours—through March 9—the storm abated. During that period, the Westmark boats got six more ships.

  • Hans-Ferdinand Massmann in U-409 sank two, the 3,800-ton American freighter Malantic and the 6,000-ton British tanker Rosewood.

  • Hans-Jürgen Zetzsche in U-591 sank the 5,900-ton Yugoslavian Vojvoda Putnik, which had incurred heavy storm damage and had been abandoned.

  • Rolf-Heinrich Hopmann in U-405, who had originally found the convoy, sank the convoy commander’s flagship, the 4,700-ton Norwegian vessel Bonneville (and one LCT landing craft alongside).

  • Herbert Uhlig in the new IXC40 U-527 sank the 5,200-ton British freighter Fort Lamy and one LCT landing craft on board.

  • Either the new IXC40 U-526, commanded by Hans Möglich, or the veteran VII U-432, commanded by a new skipper, Hermann Eckhardt, age twenty-six, sank the 4,000-ton British freighter Guido.

  Total bag from Slow Convoy 121 for the seventeen Westmark boats: eight ships for 38,500 tons plus the two 143-ton LCTs. One new VII, U-709, commanded by Karl-Otto Weber, age twenty-eight, suffered a radio-transmitter failure and had to abort.

  The convoy proceeded easterly in more reasonable weather, straight into the line of the ten Ostmark boats. On March 8 and 9, four boats of this group got four more ships for about 19,000 tons and damaged another.

  • Max Wintermeyer in the new IXC40 U-190 sank the 7,000-ton British freighter Empire Lakeland.