Black May (57 page)

To the Führer personally, at the Berghof on the Obersalzburg near Berchtesgaden on 31 May, Dönitz made the appropriate explanations, identifying Allied aircraft and radar—“We don’t even know on what wavelength the enemy locates us”—as the determining factors in his
ordering of the U-boat dispersion. A stenographer took down his words:

After naming the new detection gear and weapons that he hoped to have on stream soon, Dönitz proposed to Hitler an entirely new remedy: rapid development of a separate Naval Air Force to counteract Allied air with air of their own, with which both to fight off Allied bombers and to bomb convoy vessels.

The stenographer recorded: “The Führer agrees fully with these views.” Obviously, where the threat of Allied aircraft was concerned, Dönitz had come a long distance from August 1942, when he had stated, “The U-boat has no more to fear from aircraft than a mole from a crow.” But there is an air of unreality about this Berghof conversation. Even with new detection gear and weapons, there was hardly a chance that obsolete U-boats could again contend with enlarged Allied sea and air forces boasting state-of-the-art equipment operated by undiminished numbers of highly experienced personnel. And the likelihood that at that date, with no experience base and limited material and human resources, Germany could revive its 1930s Naval Air Arm—a fleet of over 700 aircraft was envisioned—was extremely remote, and must have been known to be so to both Dönitz and Hitler. “Just a
pipedream” is how the historian of German naval air describes it.
¹¹¹
And the U-Bootwaffe had to continue functioning under the haphazard, shortrange, and generally ineffective umbrella of land-based antishipping warfare aircraft from the Luftwaffe’s
Fliegerführer Atlantik
(Air Leader Atlantic) in western France—whose Atlantic grid charts did not even match those carried by the U-boats!
¹¹²

Of course, no one liked to recognize defeat when it came, least of all “The Lion” and the Führer: the former because he had invested his life’s energies in the U-Bootwaffe, which he had nourished to maturity from its post-1918 beginnings in 1935 and had expanded to the fleet that took to sea on 1 May 1943; the latter because he was aware that even with the reverses suffered in May, the U-boats were still his best weapon against the Allied buildup for an attempt to cross the Channel onto the Continent.

It took Dönitz fifteen years (a ten-year prison sentence adding to the time) to acknowledge in writing the emptiness of his proposals to Hitler and the disingenuousness of his bellicose pledges of final victory to the U-boats. In the pages of his memoirs that address the end of what his staffers called “Black May,” the old Admiral acknowledged the cold reality of 31 May:

“We had lost the Battle of the Atlantic.”
¹¹³

T
HOUGH SUBSTANTIALLY DEFEATED
in his campaign to throttle Britain’s maritime trade, and frustrated as well by his inability to interdict American military convoys, both to Gibraltar and the United Kingdom, Dönitz continued nonetheless to press the U-boat war in the Central Atlantic and the Outer Seas. He did so, he explained, after carefully considering his options: Should he “call off the U-boat war” in view of the enemy’s overwhelming force levels and technological advantage? Or should he “continue operations in some suitably modified form,” despite Anglo-American superiority that was likely to increase rather than diminish?

Dönitz reached the bitter conclusion that he had no alternative but to call for continuance of a sea war that was already lost. And these
were his reasons: With only no bomb-sheltered berths available at the Biscay bases, many
hors de combat
boats in base would be dangerously exposed to air bombardment. Second, a cessation of U-boat operations would free up hundreds of Allied escort vessels and aircraft that were then tied down by ASW for use elsewhere against Germany. Similarly, a unilateral stand-down would release the vast Allied network of naval and air bases, including ground service personnel and civilian workers, as well as material resources, for employment on other operations. If, for example, the Coastal Command bomber fleet, then consumed in ASW, were permitted to reinforce Bomber Command raids on German cities, the civilian populations of those cities would suffer incalculable casualties and hardships. “Could the submariner stand aside as a spectator, saying there was nothing he could or would do and telling the women and children that they must put up with it?”

Dönitz also considered a compromise strategy in which he would break off the fight until a new-generation boat, the fast electric Type XXI (see pages 387–88), became operational, at which time he would return to sea with enhanced chances of success. But that strategy would not work, he decided, since during such a hiatus the morale of even the best crews would suffer, perhaps irreparably. Furthermore, to have any chance at all, the U-Boat Arm must be in continuous engagement with the enemy in order to know his tools, tactics, and tendencies.

Among Dönitz’s reasons for staying in the game, he did not offer Hitler’s reason, namely, that fighting a now-defensive battle in the Atlantic was preferable to defending the Third Reich on the beaches of Festung Europa. Furthermore, the U-boat war served Hitler’s policy of hamper and delay. Like Frederick II in dealing with his land enemies during the Seven Years War, the Führer hoped that unrelenting attrition at sea would induce one of the Allied powers to lose heart and withdraw, if not from the war, from invasion planning. It was a foolish hope, but after Stalingrad and Black May, it was, we may assume, the only hope he had.

In light of the Führer’s Frederician policy, one must wonder if Dönitz, in drawing up his own options, really had a choice in the matter, except at the cost of his Command. By whatever route he reached
his conclusions, the Grand Admiral presented them personally to the Flotilla Commanders of the Biscay bases, who unanimously expressed themselves in agreement with them, and went on to pledge the support of their officers and crews.
²
This must have been reassuring to Dönitz. But it must also have been jarring for the Flotilla Commanders to hear their Lion step back from his long-enunciated principle: “Strategic pressure alone is not sufficient, only sinkings count.”
³

In a two-year-long dénouement that has been described extensively in the historical literature, the U-boats failed utterly to inflict further significant pain on Allied shipping, either in the Atlantic convoy lanes or in the Outer Seas. Discounted from the stature of menace to that of problem, they failed also to tie up Allied air and sea forces that might be wanted elsewhere: as early as 24–30 July 1943, Coastal Command aircraft from ASW Groups 15 and 19, with little U-boat threat to occupy them, took part in Bomber Command’s horrific firestorm raids on Hamburg.
⁴
In the Outer Seas, including the U.S. seaboard, the U-boats had occasional successes, mostly against independently sailing traffic, but none at all against American UGS and GUS military convoys in the Central Atlantic. The most sinkings were scored in the Indian Ocean. But everywhere Allied defenses had stiffened, and the boats paid a heavy price: seventy-nine lost in the three months following Black May. Among the losses were seven of the ten available Type XIV milch cows, seriously retarding future long-distance operations.

The new moon periods of June, July, and August 1943 passed without any concentrated return to the North Atlantic convoy lanes. Finally, in September, Dönitz ventured into the latitudes of prior glory south-southwest of Iceland and showed a flash of his old form in a four-day operation by nineteen boats against convoys ONS.18 and ON.202. Nine of the boats were equipped with one of the promised new weapons, T-V, or
Zaunkönig
(Wren), the “antidestroyer” acoustic homing torpedo that responded to the fast cavitation of a warship in the same way that the Allies’ Mark. 24 Mine reacted to the cavitation of a U-boat. In all, fifteen
Zaunkönig
launches were made against the escorts of the two convoys, which had joined company on the 20th.

In one of the war’s more notable examples of overclaiming, the
boats reported to Berlin twelve destroyers definitely sunk and three probably, all by T-Vs; also nine merchant ships sunk by conventional torpedoes; for the loss of two U-boats. Their success would have been greater, they added, had they possessed radar, since a dense fog hindered operations for a day and a night, when the boats were blind. The actual Allied losses were three escorts sunk and two damaged, and six merchant vessels sunk. And the U-boat casualties were three sunk (one 160 miles distant before the operation began) and three damaged.
⁵
Still, the U-boats had achieved a “success,” though a Pyrrhic one. It was to be their last convoy “success” of the war. Six more operations against North Atlantic convoys were mounted in September and October, but all were costly failures. In October the exchange rate was one merchant vessel sunk per seven U-boats sunk. The U-Bootwaffe’s condition was terminal. After a disastrous run at Convoy ONS.29 during 16–19 February 1944, no more convoy battles were even attempted, the compelling interest of the crews being, it appears, not killing, but avoiding being killed—a peculiar mission to supervene the purely offensive purpose of the craft they crewed.

By that last date, it should be noted, all the promised new weapons and devices had been supplied or fitted to the U-boat fleet. These included, in addition to
Zaunkönig
: quick-firing 20mm anti-aircraft cannon on quadruple mountings;
Naxos-U,
a search receiver capable of intercepting 10-centimeter radar, first introduced (after an incredible delay) in October 1943; and
Aphrodite
, a radar decoy consisting of aluminum foil streamed from a hydrogen-filled india rubber balloon that simulated the radar signature of a conning tower.
⁶
But, as Günter Hessler conceded, “all the new weapons together could not give back to the old-type boats their striking power.”
⁷
An engineering innovation that did improve the old boats’ safety if not their performance was the
Schnorchel
(a dialect word for “nose”), a double-pipe system invented before the war by the Royal Netherlands Navy that enabled a submarine to cruise and charge batteries on diesel power while submerged at, roughly, periscope depth. The “breathing” pipes that extended above the surface brought in air for human consumption and diesel combustion, while at the same time discharging exhaust. The snorkel returned
to the U-boat what had once been its principal advantage: stealth, which at this stage meant, in practical terms, protection from aircraft. There were certain offsetting disadvantages, however. Underwater speed on the diesels was not high, and a crew’s health and comfort, even life, were threatened when carbon monoxide-laden exhaust gases leaked into the boat’s interior, or when the float valve on the intake pipe suddenly closed owing to surface turbulence or miscalculation by the planesmen, and all interior oxygen was sucked away by the engines.

Eventually, the single advantage possessed by snorkel-equipped boats was defeated by American development of 3-centimeter radar that picked up the head of the U-boat’s pipes. Snorkel as well as non-snorkel boats failed miserably to interdict the Normandy invasion fleet of 6 June 1944 or to obstruct the buildup fleets that followed during that month, while RAF Coastal Command’s No. 19 Group made easy sport of them. From Normandy to war’s end, U-boat effectiveness continued its precipitous decline. A final look at exchange rates reveals how far the numbers plummeted. From July 1943 to the final surrender in May 1945 the exchange rate was 0.5 merchant vessels sunk per U-boat sunk. That was one-eighth the rate for the eight-month period from October 1942 through Black May, and one-thirty-sixth the rate for the eight months preceding that.
⁸

The one weapon that stood even a theoretical chance of turning the sea war in Germany’s favor was the 1,600-ton Type XXI (and its much smaller 250-ton Type XXIII stablemate) “electro-boat.” The first large true submarine (all earlier boats being submersibles), the XXI housed a heavy high-capacity battery array that enabled the boat to proceed submerged at an unprecedented 17½ knots for one hour’s time, or at five knots for a full twenty-four-hour day. Such high underwater speed, assisted by a streamlined hull, gave it virtual immunity to the depth charge and Hedgehog, while submergence itself vitiated the probing pulses of airborne radar. Fitted with
Schnorchel,
the boat achieved 10 knots submerged on diesels. It also had remarkable fighting qualities, including the capability of launching eighteen out of its complement of twenty torpedoes inside of 20 minutes. So advanced was the XXI design that it became the template for all immediate postwar
submarines commissioned in the U.S., British, and Soviet Union navies. But it never got into the war at hand.

One reason late in the game was RAF Bomber Command, which, in one of its few undisputed successes during the war, created such destruction among the dockyards in Bremen, Hamburg, and Kiel, where the XXIs were being assembled, that production was slowed, workups in the Baltic and Norway were delayed, and U-boat ranks and ratings wondered if they would ever have the chance, before what looked in early spring 1945 to be inevitable surrender, to test the promise of their true submarine. Even at that late date, the German Navy was methodical and conservative. Some “30 to 50” XXIs, according to Hessler, were nearly finished with their trials but were held back for formal completion; six were in Norway finishing snorkel trials; and only
one,
U
-2511,
was released for operations. Under command of Korv. Kapt. Adalbert Schnee, that precursor boat sailed for the Faeroes between the Shetlands and Iceland. There, on 8 May, Schnee received a “You have fought like lions” surrender signal from Dönitz, who had succeeded the suicided Hitler as Führer:

Several hours after reading the long-dreaded message, Schnee sighted a British cruiser and destroyer escort. He decided to make a dummy attack in order to convince himself that the XXI was as good as advertised. Proceeding submerged, with no trouble he inserted himself inside the destroyer screen and made a textbook simulated attack on the cruiser at close range with six torpedoes. It was the first successful “attack” by a new-generation submarine of that size under action conditions, after which U-2511 returned to base, as instructed. Prior to Schnee’s simulated action, the XXI’s smaller version, XXIII, proved itself in eight sorties by eight boats between 30 January and 7 May 1945, resulting in seven merchant ships sunk for no losses to themselves. But the promise and the reality were too late to make a difference.

During the two years that followed Black May, no threat to the U-hoats was more pervasive or feared than bombs from the air. On 27 April 1943 Dönitz had made a carefully calculated decision that boats transiting the Bay would be safer spending their necessary battery-charging time on the surface in daytime, when they could sight approaching aircraft and defend themselves with flak, rather than at night when, without warning or defense, they might be exposed to the searchlights and bombs of an L/L Wellington or Catalina. Where he erred was in thinking that his anti-aircraft armament was robust enough to provide an effective defense. Most boats had twin 20mm. cannon, but what was needed, at the least, was “Quad Twenties,” and those mountings were not fitted fleet-wide until later in the year.

An additional measure of defense was provided starting early June 1943, when BdU initiated U-boat convoys: boats were ordered to depart their bases in groups of three to five, on the surface, in daylight, and to use their combined firepower if challenged by aircraft. The thinking was that an aircraft carried only enough ordnance to take on a single boat. But Coastal pilots responded to this innovation by flying together in loose formations so that one, on sighting a U-boat group, could summon the others for mass attack. Dönitz halted group sailings on 12 June but resumed them at the end of the month. On 17 June, he reduced the U-boats’ daylight surface hours to the minimum four to six in every twenty-four required to keep a charge on the batteries.