Black May (8 page)

Men scrambled up the tower ladder, then down the tower sides, and mustered on the tossing upper deck—though not all of them, since it appears that some of the engine room personnel and radiomen remained on duty too long to make their escape, and that both Stock and the I.W.O. similarly got trapped below. Among the officers, in fact, only the L.I. made it out. Survivors stated that the radio operators got off a short signal reporting both the boat’s loss by ramming and her
position, 43°32'N, 13°3o’W. Five minutes after the collision, a towering wave broke over the mortally wounded frame of U
-659.
The men on deck went flying into the water, and the boat, heeling over to starboard, sank from view.
⁴⁸

The other boat was
U-439,
a Type VIIC commanded by Oblt.z.S. Helmut von Tippelskirch (Crew 37). A native of Cuxhaven, the twenty-five-year-old Kommandant had earlier served as I.W.O. on U—
160.
The U
-439,
his first command, had departed Brest on 27 April, and on the night of 3/4 May occupied a station adjoining U
-639
in the
Drossel
line, from which she was proceeding this night at the highest speed that the sea state permitted, to intercept the first of the two reported southbound convoys. By 0100 GST she sighted the convoy and by 0325 she was positioned ahead of it, making seven knots. At that instant, survivors from his boat said, Tippelskirch altered course slightly to port and his bows rammed the starboard side of U
-639,
which no one had seen. Tippelskirch immediately ordered both engines full astern, but the maneuver in rough seas caused the diesel exhausts to drown and the interior of the boat to fill with blue fumes. Because the collision had caused heavy leakage through the two port bow torpedo tubes, the bow compartment had to be closed off.

Meanwhile, the L.I. tried to adjust the surface trim by blowing the forward ballast tanks, but these, it was discovered, had been damaged in the collision. He compensated by flooding some of the after tanks, but this brought the boat dangerously low in the water, and the L.I. recommended abandonment. Tippelskirch, thinking the boat might yet be saved, ordered the engine room personnel and radio operators to remain at their stations and the remainder of the crew to go up on deck with their life jackets. There they saw that their boat was down by the bows and already half-submerged. Survivors doubted that the radiomen’s distress signals were heard, since most of the forward transmitting antenna wire was underwater. Said one:

They did not receive it.

From the bridge Tippelskirch could see the other U-boat not far distant. Though it appeared to be in a sinking condition, he asked it by signal lamp for assistance; but U-659 replied by lamp that she, too, was going under. Then a huge rogue wave, probably the same that swamped Stock’s boat, drove U
-439,
still carrying inside about twenty-four engine machinists and radiomen, into the 2,761-fathom deep, a bourn from which none returned. Those men who had been on deck, thrown off violently from their tenuous footing, swam off with flashing signal lights, hoping to attract either other
Drossel
boats or, just as well given the circumstances, the enemy.

At 0500, British Motor Torpedo Boat 670, leading the starboard column of the first reported southbound operational Coastal Forces convoy, ran into diesel smoke and fumes, and afterwards sighted men swimming in the water. The starboard column stopped and rescued twelve survivors, three from the forty-five-man crew of U-639, and nine from the forty-eight-man crew of U
-439.
The only officer among them was the L.I. of U
-639.
Taken first to Gibraltar and then on 13 May to the Combined Services Detailed Interrogation Centre, U.K., at Latimer House, Chesham, Buckinghamshire, England, the survivors underwent the usual interrogation by RN officers. The nine from U—
439
proved particularly intractable, and the interrogators reported, “They were mostly more security-conscious than has been the case among recent U-boat prisoners of war.”
⁵⁰
All they would say about their Commander, Tippelskirch, was that he was adventurous and very popular with his men, but that, having teethed on a Type IXC (U—/160), he always had difficulty handling a VIIC. About the I.W.O., Oblt.z.S. Gerhard Falow, they had mixed feelings: on the one hand, they found him easygoing and well-liked; on the other, they thought him lazy and personally responsible for the loss of their own boat, and of U-659 as well.

Apparently, Falow himself, before his watery death, agreed with
that last judgment, as the British learned in detail from the secret bugging of twenty-one-year-old Herbert Apel, a
U-439 Maschinengefreiter
(the U.S. Navy equivalent: Fireman, third class; the Royal Navy: Stoker, second class). The interrogators housed Apel in a POW hut with a
Steuermann
named Schultz from SS
Regensburg,
a German blockade-running freighter that had been sunk by the cruiser H.M.S.
Glasgow
off the north of Iceland on 30 March. The interrogators knew that a man from one boat or ship would want to relate his experiences, knowledge, and thoughts to someone he did not know from another U-boat or ship.

Accordingly, on 21 May Apel described to Schultz (and through hidden microphones to the British listening post) how Tippelskirch erred by placing a man on lookout duty who had no previous experience of watchkeeping in that boat; and how the I.W.O. Falow erred by taking more interest in events occurring in the port quarter than in the seascape on the starboard sector which was his responsibility—though Falow did take the ultimate responsibility for the dereliction, as Apel explained:

A
PEL
: Do you know what our First Officer of the Watch did? Anyone else would have fetched it [a lifebelt] for him, and someone else did fetch it, and brought it to him. He said: “I won’t take anything.” Well, of course, we were absolutely staggered that he wouldn’t take the lifebelt. Then he went and stood forward on the bridge. He gripped the bridge with both hands and went down with the boat like that. At the time of the mishap he was on the bridge. The boat which we had rammed appeared in his sector. Of course, he would have been definitely held responsible in Germany. To be quite honest, it was our fault—or rather it was the fault [of those] on the bridge. We had a new
Bootsmaat
[Petty Officer Third Class (USN)] on the patrol. He’d never been on watch at all. At six o’clock in the evening, the Commander sent for him and said: “You’ve been on watch on the bridge in the other boat, haven’t you?”—“Yes.”—“Can you see well at night, too? Have you sighted anything yet? You’re sure you can do it?”—“Yes.”—“Good, you can do watch on the bridge tonight.” He [the
Bootsmaat
] stood forward…. And suddenly on the port side of
the boat, aft, tracers were seen, so there must have been some firing— so [the port quarter lookout] naturally thought that must be the convoy, and reported it at once. The Officer of the Watch was interested, turned round and had a look. The Commander was on the bridge and looked, too. The [new
Bootsmaat
] forward, who should really have continued to look straight ahead, looked round too, and the Commander said to the two look-outs [forward]: “Pay attention, don’t look over there, that doesn’t concern you. Something may come from any side.” Until now that [policy] had always been so, and had always been successful, and this time apparently he didn’t say that to the new
[Bootsmaat].
He should have known it himself. There was more firing. The others kept their eyes glued to their sector, when suddenly the Officer of the Watch turned round and yelled: ”
Verdammte Scheisse—A.K. zurück!”
['Hell and damnation!—full speed astern!"] But it was already too late.

S
CHULTZ:
Perhaps the boat didn’t sink at all. You can’t possibly tell.

A
PEL:
She definitely went down. She heeled over almost vertically and went down like that. The diving tanks were still full of air. She probably stopped sinking at two hundred meters, three hundred meters, or even three hundred fifty meters for about half an hour, and then, in time, she would get heavier and heavier as more water came in.

S
CHULTZ:
Yes, but they can still blow the tanks or—

A
PEL: No
, no. Our whole bow compartment was under water. Forward in the bow compartment the bulkhead was closed. It was a watertight bulkhead but will not stand up to heavy pressure. The lower bulkhead will certainly have caved in. Even before, it was never quite watertight, water already came.…

S
CHULTZ:
There’s no proof at all that the men are dead.

A
PEL:
Oh yes. Just think, where could they blow the tanks? First, the diving tanks were still full of air, but there was water in the boat…. We were unlucky. We started up both pumps immediately and we were unable to get rid of a single drop of water that had broken in.
⁵¹

Another closemouthed survivor, but from the other boat involved in the collision, was Bruno Arendt, a twenty-three-year-old
Bootsmann
(the U.S. Navy equivalent: Petty Officer, First Class; Royal Navy:
Chief Petty Officer). Quartered with Helmut Klotzsch, the
Obersteuermann
(Navigator) of U-175, sunk on 17 April, Arendt was heard to say (and recorded) on 13 May:

A
RENDT:
The Interrogation Officer wanted to know the number of the boat, but I won’t tell him that.

K
LOTZSCH:
What number did you have?

A
RENDT:
Six-fifty-nine.

K
LOTZSCH:
Some two hundred boats have been sunk already.

A
RENDT:
They will make a fine mess of things this summer. There is no question of there being more boats operating now. As soon as they come out they’re sunk…. By the time you’ve sailed for three years you’re just about finished.

K
LOTZSCH:
Yes, I know an Obersteuermann who is now on his sixteenth patrol.

A
RENDT:
Well, let him get that over safely, and then he’ll go on his seventeenth and that will be the end of him! Twelve men [from our two boats] were saved altogether.

K
LOTZSCH:
Twelve men from two boats?

A
RENDT:
Yes. There were forty-eight in our boat. That’s ninety-six in the two boats.

K
LOTZSCH:
It’s a tragedy. The whole business of U-boat sailing has simply become a job for convicts.
⁵²

Two sets of omens. Which would prevail? The triumphant auguries of Henke (U-515) and Gelhaus (U-107)? Or the woeful auguries of Stock (U-659) and von Tippelskirch (U-439)? But pantomancers were probably few on either side. More dully, the slogging procession of May would tell.

B
Y THE DATE OF THE EVENTS
described in this narrative the major forces, directions, and trends in the Atlantic campaign had long been established. There is no need to review all the operational details of the war at sea from the outbreak of hostilities on 3 September 1939 to the beginning of May 1943, since these have already been essentially
addressed in the historical literature. But before considering developments in Allied armed countermeasures to the U-boats, which is the intent of this chapter, it might be helpful to tease out of the previous forty-four months of data several findings that are surprising and provocative.

The first of these relates to numbers. At the outset of war, Dönitz had only thirty-nine operational U-boats, including twenty-two Type VIIs and Type IXs—instead of the 300 he had stated was the minimum number he would require to conduct a successful war against Great Britain’s Atlantic trade, and instead of the 162 oceangoing boats he had been promised by Hitler in the naval construction program scheduled for completion in 1948(!). Of these twenty-two, only six to eight could be deployed on operational stations at any one time, the remainder being in transit or in repair yards. Through February 1941 his available force declined in number rather than grew, despite the successes of the first year and five months, which included the sinking of the battleship
Royal Oak
by U
-47
(Korvettenkapitän [hereafter Korv. Kapt.] Günther Prien) on 14 October 1939 and a five-months-long U-boat spree in waters adjacent to the United Kingdom and Ireland from June to October 1940 that added 1,395,298 enemy GRT to Dönitz’s bar graphs and became known among U-boat crews as
glückliche Zeit
—the “Happy Time.”

Those successes, gained mainly against nonconvoyed, independently routed ships, unquestionably impressed Hitler, but the Führers favor was not reflected in his allocations of steel and workers for U-boat construction, with the result that, owing to combat losses, in February 1941 Dönitz commanded fewer operational boats (22) than he had on the first day of war. In that month, however, the delivery rate improved, and by the end of July 1941 the number of operational boats surpassed Dönitz’s original number. The increase would be sustained thereafter with occasional slight diminutions (May-June 1942, October 1942-January 1943, and March-April 1943) until May 1943, when Dönitz would have no fewer than 433 boats in commission (207 operational in the North Atlantic theater).

One might have expected that after mid-1941 the U-boats’ success
rate would increase at the same rate as that of new commissionings. But such was not the case. From July 1941 forward, sinkings decreased markedly. From 305,734 GRT of Allied shipping sunk in June 1941 the totals fell to 61,471 in July and 67,638 in August. Whereas in September 1940, when an average of thirteen operational U-boats were at sea, Dönitz’s commanders had sunk 265, 737 GRT, for an average of 753 GRT per boat per day at sea, one year later, in September 1941, when an average of 36.5 boats were at sea, his commanders sank only 208,822 GRT for an average of 186 GRT per boat per day. The tonnage sunk in October 1941 dropped to 182,412 GRT, that in November to 91,628 GRT, and the total in December was 101,687 GRT, with correspondingly low GRT averages per boat per day. In other words, during 1941 the more operational boats there were, the fewer their successes.

And 1941 is not the only period in which we notice that discrepancy. As indicated in the prologue, the greatest monthly toll of Allied shipping lost to U-boats in the war (743,321 GRT) was taken in November 1942, a month in which the U-Bootwaffe had 95 operational boats at sea. Their average sinkings per boat per day were 220 GRT. Two years earlier, in November 1940, when there were only 11 operational boats at sea, the average sinkings per boat per day were 430 GRT. With nearly nine times the number of boats, the U-Bootwaffe in its best month of the war scored slightly more than half the successes per boat of those achieved by their forerunners.

In January, February, and March 1943, which are closer to the special focus of this narrative, there were 92, 116, and 116 U-boats, respectively, operating in the Atlantic, where sinkings were, again respectively, 218,449, 380,835, and 590,234 GRT. Taken alone, these were impressive figures, augmented in no small part by the mauling of SC.122/HX.229 in March; but considered in terms of the large operating force at sea in those months we find that the tonnage numbers credited to each boat per day at sea were 65, 99, and 147 GRT, which, taken together, represented no improvement over the figures posted during the second half of 1941.
¹
Dönitz was still sinking fewer merchant ships per investment of U-boat days.

Returning to 1941, where we first notice a sharp falloff in U-boat productivity,
we can ask, how may it be explained? One reason that has been offered is the sudden loss of three individual U-boat “aces” in March: Prien (U
-47)
and Kptlt. Joachim Schepke (U
-100),
both of whom were killed, and Korv. Kapt. Otto Kretschmer (U-99), who was captured. These commanders, who had first made their reputations in the “Happy Time,” had achieved tonnage totals ranging from Schepke’s 156,941 GRT to Kretschmer’s 257,451. All were
Ritterkreuzträger
, winners of the Knights Cross of the Iron Cross, with Oak Leaves, and, as such, were inspirational role models for the rest of the officer corps.

Fregattenkapitän (hereafter Freg. Kapt.) Günter Hessler, Dönitz’s son-in-law and a member of his operations staff, stated after the war that the U-boat successes prior to July 1941 were not “due only to the skill of such men as Prien, Kretschmer and Schepke, for there were equally competent commanders in 1941, who however had to contend with much greater difficulties.”
²
He may have had in mind such men as Kptlt. Engelbert Endrass (U-45, U-567), Korv. Kapt. Reinhard Suhren (U
-564),
and Kptlt. Adalbert Schnee (U
-201).
Endrass would be lost in December 1941. Postwar analysis, however, would place an emphasis on how important for the U-Bootwaffe’s overall success was the performance of certain individual commanders, whose loss would be a pronounced negative. No more than thirty-commanders (2 percent of the whole), it was found, accounted for some 30 percent of Allied shipping sunk by U-boats during the war; and, significantly, for what it said later about replacement commanders, all had entered the Kriegsmarine before 1935. Only fourteen commanders accounted for nearly 20 percent of all sinkings. Only 131 boats sank or damaged six or more ships. Meanwhile, 850 boats, which represented three-quarters of all boats commissioned during the war, failed so much as to damage a single merchant vessel.

With these figures in hand, Günter Hessler notwithstanding, the argument that the loss of three proven performers in Prien, Schepke, and Kretschmer had an adverse effect on U-boat fortunes in July-December 1941 is, though not decisive, persuasive. As has been written, “One cannot leave the subject of human factors without re-emphasizing the importance of the aces on both sides…. Kretschmer, Prien
et
alia
were good enough to distort all statistics. The difference was that [Allied] escort commanders lived to improve their skill and to pass it on, whilst U-boat aces had a short life.”
³

Another reason more frequently, and convincingly, offered is the acquisition by the British, in February-June 1941, of access to secretly encrypted radio traffic between Donitz and his boats. The story is now a familiar one. For secret radio communications the three German armed forces, land, sea, and air, employed a once commercially available electrical-mechanical encryption machine. Called Enigma, it resembled a typewriter with a standard keyboard, which was used for punching in the message to be encrypted. Above the keyboard were three (later four) rotors, and below the keyboard facing the operator was a plug board. By altering the rotor settings and plug pairings each day, it was estimated that the possible permutations created by the machine approached one hundred and fifty million million million, a number maintained by German cipher experts to be beyond solution. But in 1934 Polish Intelligence Service mathematicians, by yoking six Enigma machines together, did find a partial solution. They managed to pass on their findings to French cryptanalysts, thence, after France, too, fell, to the cryptanalysis establishment at the (mostly) fictitious Government Code and Cipher School (GC&CS) in England.

Housed in a red-brick mansion in pseudo-Tudor-Gothic style at Bletchley, halfway between Oxford and Cambridge, GC&CS had already made substantial progress against Enigma on its own. Under the direction of academics, notably the Cambridge mathematician Alan Turing, GC&CS constructed an electromagnetic scanning machine called the
Bombe.
Fed to the Bombe’s innards, intercepted German signals traffic began to shed its veils. First to be read was Luftwaffe (Air Force) Enigma, on 22 May 1940. Shortly afterward, the machine decrypted Wehrmacht (Army) traffic. Single-story white-frame Nissen huts sprang up behind the mansion to house academics who translated and interpreted the incoming German messages. Hut 8, however, which was assigned to naval traffic, was frustrated by the Bombe’s inability to penetrate the Kriegsmarine’s more complex U-boat cipher, generated by the marine version of the Enigma machine,
Schülssel M
(Marine-Funkschlüssel-Maschine M).
Naval Enigma, in fact, would resist for a full year until finally forced to submit in winter-spring 1941.

What Hut 8 had needed to resolve the impasse were operational wired rotors and operators’ handbooks that gave daily Schlüssel-M settings and pairings. In a series of “pinches” conducted from February through June 1941, the Royal Navy obliged. On 12 January, off a captured crewman of the sunken U
-33
in the North Channel between northern Ireland and Scotland came rotors. On 4 March, from the wrecked German whaling trawler
Krebs
off the coast of Norway, came key tables and settings. Armed with these materials, Hut 8 could then read U-boat traffic in the
Heimische Gewässer
(Home Waters) key for the entire month of April. More pinches were to follow. From the captured weather ship
München
east of Iceland on 7 May came settings and keys for June. And, the
pièce de resistance
, two days later, destroyer H.M.S.
Bulldog
boarded U-110 (Kptlt. Fritz-Julius Lemp) in mid-Atlantic and came away with a Schlüssel-M including spare rotors, a Home Waters handbook with daily settings and pairings, special settings for
Offizier
, officer-only, signals, and short-signals (
Kurzsignale)
code books, all valid to the end of June.

Included also was the first captured naval grid chart of the North Atlantic and most of the Mediterranean. This chart,
Nr. 1870G Nordatlantischer Ozean,
with land surfaces in green and water surfaces in white, was divided into blue-lined squares, each identified by a digraph; for example, going west to Newfoundland a U-boat would pass through naval squares BF, BE, BD, BC, and BB. Each artificial square, about 486 nautical miles per side (along 50° latitude) was subdivided into nine smaller squares identified by double-digit numerals, from 11 to 99. Each smaller square was then subdivided nine times, then nine times again to form a fine screen that could take positions at sea down to a
Marinequadrat
(naval square) no larger than six nautical miles to a side. Typically, a U-boat’s position in radio messages and war diaries would read as follows: ET 6278, which was Werner Henke’s position in U-515 when he sank his first four ships southwest of Freetown on the night of 30 April/1 May. The naval square coordinates would be used by the U-Bootwaffe throughout the war in the place of latitude and longitude. A square was usually cited as
quadrat,
or
qu.

When this godsend was received at GC&CS, Hut 8 began reading the other side’s mail much closer to the grain. More help was to come. In a tightly planned operation on 28 June, British cruisers and destroyers boarded a second weather ship,
Lauenburg,
in the Norwegian Sea and captured the Home Waters key for July, allowing for continued Hut 8 penetration during that month. By mid-August 1941 Hut 8 had no further need of pinches and was able on its own to decrypt the key within fifty hours of transmission (41 hours in September, 26 in October). There had been brief blind spots on 1–4 August and 18–19 September, but from November forward the key would be read daily with virtual currency until war’s end.
⁴
The only downside to that success was that beginning in February 1942, Home Waters’ use for U-boat operations would cease, to be replaced by a new, more intricate cipher key named
Triton.
Employing a fourth rotor in the Enigma machine, Triton would remain impenetrable for nearly eleven months.

In the meantime, from July forward, GC&CS was able to send U-boat decrypts by secure circuit to Commander Winn and Lieutenant Beesly in the Submarine Tracking Room of the Operational Intelligence Centre of the Admiralty, where U-boat positions for the first time could be established confidently on the Main North Atlantic Plotting Table that depicted latitudes and longitudes 73°N to 5°S and 100°W to 60°E. When received there, the decrypts were given the designation “Special Intelligence,” or “Z.” When the essential information contained in the decrypts, though never the raw decrypts themselves, was signaled by OIC to headquarters, base, and fleet commanders, it became known as “Ultra.”