Black May (2 page)

In any event, the stage was set in April for a decisive collision of the forces at sea, when Whitehall expected that, once refitted in Biscay bases from their exertions of March, the U-boats would return to the convoy lanes with even greater strength than that seen in the month before. If the ides of March was bad, that of April might be worse. As it happened, though, April was not the cruelest month at all. Sinkings by U-boats actually went down, to forty-eight ships for 276, 517 GRT, which was 47 percent of the March losses. And the U-boat per day at sea number was a low 127 GRT estimated, 76 actual.

One reason was a declining number of operational U-boats on North Atlantic stations, owing to longer-than-expected refit time at the Biscay bases, where many boats in need of repair, fuel, food, and armament replenishment had to lie for days in vulnerable berths outside the bombproof service and repair bunkers.
¹⁴
By the ides of April (13 April), only thirty-three boats were on operations, and only one battle group, code-named
Meise
(Tit, a small European bird of the family Paridae), was formed, northeast of Cape Race, Newfoundland. Admiral Dönitz’s U-Boat Headquarters (called
BdU,
from
Befehlshaber der Unterseeboote
[Commander-in-Chief, U-Boats]) in Berlin considered the problem in its war diary for 16 April:

Not until the latter part of the month was the U-Bootwaffe able to dispatch a sizable fresh stream of boats, and so provide the numbers at sea on 1 May given at the beginning of this prologue. Sinkings of merchant ships declined for another reason as well, namely the larger number and effect of Allied convoy escorts, both surface and air, that Britain was able to deploy at sea in this month. Thus, though eleven
convoys were attacked in the month, and all sustained losses for a total of twenty-nine sinkings, a stronger force of Allied ocean escorts, which included new “Support Groups” of emergency-directed escort warships and two auxiliary aircraft carriers, repeatedly drove off the German attackers and sank fifteen of their number, seven in the last week of the month. (U-boats sank twelve independently routed merchant ships in April.) Ten eastbound (234 ships) and nine westbound (182 ships) Atlantic convoys reached their destinations without interception.

There also appears to have been either an unaccountable decline of U-boat aggressiveness during the month, or else a surge in OIC Tracking Room wishful thinking on the subject, since it is here that one first reads an expression that is repeated in various British documents composed in the months thereafter: “It was in April that, for the first time, the U-boat groups failed to press home attacks even when favorably situated to do so.”
¹⁶
The “failure to press” was detected during Commander Winn’s analysis of decrypted wireless (radio) transmissions between the U-boats and their headquarters, particularly with respect to the traffic’s frequent mention of Allied aircraft, whose number and threat had increased. “The outstanding impression felt on reading recent U-boat traffic,” Winn observed, “is that the spirit of the crews which are at present out on operations in the North Atlantic is low and general morale is shaky.”
¹⁷

If true that there was such a holding back, it is difficult to understand why such caution would be credited to a lack of will or morale. There certainly may have been sinking feelings—even despondency— at Berlin, where officers studied doleful statistics; but if Royal Navy frontline morale had not cracked under the unremitting strain of three and a half years of convoy losses, it is hard to conceive that U-boat ranks and ratings (officers and enlisted men), just off a staggering triumph at sea, would have lost heart simply because they sighted additional numbers of aircraft, or because they were failing to keep up with the exceptional sinking rate of the month before, while suffering, it should be added, no more U-boat losses (15) in April than they did in March. Vizeadmiral Horst von Schroeter, who as
Oberleutnant zur See
[hereafter
Oblt.z.
S.] commanded U
-123
on operations during April, told this writer in December 1995 that morale remained high on his
boat and that he noticed no special decline among other crews when he returned to base at Lorient. Were there, then, no “low spirits” as detected by Winn?

If the Tracking Room observation was true that certain U-boats exhibited reluctance to attack targets with the expected dash and initiative, one likely reason was their reduced levels of command experience, owing to U-boat officer casualties that included not only Commanders but First (I.W.O.) and Second (II.W.O.) Watch Officers, who had merited their own boats. The BdU addressed this problem in its war diary for 7 April, and again near the end of the month, on the 25th, when it did a wash-up on a botched attempt by nineteen boats of the
Meise
group to operate against eastbound convoy HX.234 on 21–24 April: Noting conditions of “extremely changeable visibility” on the seas south of Greenland, the diary commented that, “The Commanders, for the most part inexperienced and fresh from home waters, were unable to cope with those conditions.”
¹⁹
Yet, having said that much in mitigation of the Tracking Room’s interpretation, it is also true that BdU found reason, on 19 April, to admonish Commanders at sea for their lack of “warrior and fighter instincts.” This astonishing message, decrypted and read by the British, was occasioned by the apparent acceptance among some Commanders of a rumor that Allied escorts left depth charges, with timers, suspended from buoys:

Whatever the meaning of April’s various mixed signals, it is enough to say that at month’s end the pendulum that had swung so far in Germany’s favor during March had returned by 30 April to center. For Dönitz the prognosis should have been clear: the tonnage battle was not winnable. Since the previous fall the figures for Allied merchant ship construction had passed and had continued to exceed with everincreasing plurality the figures for merchant ship losses; and by July 1943 the construction gains would overtake losses caused by U-boats
plus
all other enemy action, e.g., mines, aircraft bombs, surface raiders, and
Schnellboote
(S-boats, 105-foot fast torpedo boats).
²¹
Despite growing evidence that his U-Bootwaffe lagged behind the curve, with little real chance of catching up, Dönitz persisted in talking as though the struggle for tonnage was still a war-winning strategy. Thus, on 11 April, to Adolf Hitler, at the Führers Berghof on the Obersalzburg near Berchtesgaden, in Bavaria, Dönitz pleaded that an increased allocation of 30,000 tons of steel be made to the U-boat yards in order to make possible a stepping-up of construction to twenty-seven boats per month. Hitler agreed with Dönitz’s argument, which included the following language:

In continuing to promote the tonnage battle, Dönitz may well have thought that his boats and crews were capable of mounting one last transcendent effort, which, while it could not hope to reverse the merchant ship replacement gains, would at least make the rate of ship and cargo losses in convoy unacceptably high to the Allies. If such an effort
could be uncoiled and sustained for a month’s period—here one can only speculate about his intentions and expectations—perhaps Britain would give up on convoys and scatter her seaborne trade in independently routed vessels—a not unreasonable expectation if certain Admiralty reports and histories were believed. Against such unprotected shipping his U-boats could then prowl and strike at their ease (with one eye cocked for aircraft). Was this the Grand Admiral’s desperate hope? Would he now commit all his boats in one last throw of the dice?
Spes contra spem?

Then, as though to confirm the plausibility of his continued faith in the tonnage battle, on the night of 30 April/I May a single German boat, U-515, commanded by thirty-three year-old Kapitänleutnant (hereafter
Kptlt.)
Werner Henke, carried off one of the most spirited and successful actions by a U-boat in the entire Atlantic campaign, sinking seven convoyed ships of 43,255 GRT in the space of eight hours and forty minutes, torpedoing four of them within six and a half minutes! Here certainly was a higher efficiency of boats and perhaps the beginning of a transcendent effort. If what Henke achieved at the opening of May could be extrapolated by his and other boats, at the same pace, until the end of May, Dönitz would have his 1.3 million GRT in a single month’s time.

T
HE
U-515
WAS ON HER THIRD
operational patrol since the longrange Type IXC boat emerged from the yards of Deutsche Werft at Hamburg-Finkenwerder and Werner Henke raised the national flag and his Commander’s pennant above her conning tower at the
Indienststellung,
or formal commissioning, on 21 February 1942. After six months of workup and tactical exercises, she had made her maiden war patrol,
and Henke’s first as a
Kommandant
, on 12 August-14 October 1942 off Trinidad and Tobago in the southeast Caribbean, netting ten Allied ships sunk, for a total of 52,807 GRT; a not-inconsiderable tally for a single cruise, even given the fact that Henke was operating against mostly independently routed ships in a weakly defended area. It was a score outdone by only a handful of German boats during the war, and matched by only one U.S. Navy submarine in the Pacific (U.S.S.
Tang
in June-July 1944).
¹

The U-
515’s
second cruise, on 7 November 1942–6 January 1943, off Gibraltar and the Azores, resulted in only two sinkings, but one vessel was a Royal Navy destroyer depot ship, H.M.S.
Hecla
(10,850 tons), and the other a passenger liner-troopship,
Ceramic
(18,713 GRT). The loss of life from the two ships had been dreadful: 279 lost from 847 ranks and ratings on the former; all but one of 656 on the latter. By 30 April 1943, U-
515’s
third patrol, begun on 21 February, was already one of the longest of the war, and due to grow longer still. Operating off first the Azores and then Dakar in Senegal, on the bulge of West Africa, U-
515’s
third cruise, like the second, had been mostly a run of bad luck, with only two merchant trophies of 10,657 GRT to show for sixty-nine days of steaming—a poor individual tonnage rate per sea-day of 154 GRT.

The first sinking had come on the evening of 4 March while U-
515
was northwest of the Azores. On a calm sea with little wind and good visibility, Henke sighted a large freighter proceeding independently at 15 knots on a course of 050° (degrees). He advanced on the surface toward the target. What happened next he described in his war diary
(Kriegstagebuch,
hereafter
KTB):

The
California Star,
which carried general cargo as well as food, was a motor ship of British registry. Fifty of her seventy-four men on board were killed, fatally wounded, or drowned. The sinking took place at latitude and longitude coordinates 42°32'N, 37°20'W. On 21 March and 1 April U-515 rendezvoused with two returning boats, U-106 (Kptlt. Hermann Rasch) and U-67 (Kptlt. Günther Müller-Stockheim), to take on fuel, provisions, and spare parts. Henke’s second success on this patrol came thirty-six days after the first, on 9 April, at night, while steaming off Dakar. This victim, the French motor ship
Bamako,
was a smallish 2,357 GRT, slightly overestimated by Henke:

Twenty of the ship’s thirty-seven crew and passengers went to watery graves at position 14°57'N, 17°15'W.

The wages of war were not only bottoms and cargoes—a reminder, if one were needed by affronted humanity, that the fragile tissue of men was no equal to the violent and deadly instruments that roamed the spring Atlantic seeking whom they might devour. In that connection, it bears mention that if there has been a general fault with histories of the Atlantic war it has been their tendency to concentrate on the uniformed fighting services of sea and air, while giving scant notice to the civilian British, American, and other Allied merchant seamen who experienced the most danger of U-boat attack at sea and suffered by far the most human casualties.
⁴

A summary of wartime losses in the British Merchant Navy makes
the point: about 185,000 merchant seamen served aboard freighters, tankers, and motor ships, of whom 32,952, or 17 percent, lost their lives. That was a higher casualty rate than the 9.3 percent suffered during the war by the Royal Navy, the 9 percent by the Royal Air Force, and the 6 percent by the British Army. To the merchant seamen casualties must be added losses suffered by Royal Navy and Army Royal Regiment of Maritime Artillery gunners who served aboard most merchant vessels and were colloquially called D.E.M.S. ratings, after Defensively Equipped Merchant Ships.

Henke’s U-boat was a Type IXC
Atlantikboot,
an improved version of two earlier submarine models, IXB and IXA, which had been built in the late 1930s and 1940 to specifications close to those of a World War I boat, U—81. The IX series had been envisioned originally as command and control boats, in which tactical group (“pack”) leaders could direct operations at sea (an idea abandoned in late 1940); also as reconnaissance and mine-laying boats; and, finally, as long-range high-seas attack boats. In the last capacity, Types IXB and IXC boats had conducted immensely successful torpedo operations against Allied shipping as far distant as the United States East Coast, the Caribbean Basin, and the coast of West Africa.

Because of their large displacement (1,120 tons, surfaced) and wide, flat upper deck, the Type IX boats received the sobriquet
Seekuh
(sea cow), after aquatic herbivorous mammals like the manatee. The IXC was 76.8 meters (254 feet) in length—about 21 feet longer than today’s Boeing jumbo jet 747–400—and 6.8 meters (22¼, ft.) across the beam. Surfaced keel depth was 4.7 meters (15½. ft.). Its fuel bunkers, or tanks, had a capacity of 208 tons, allowing for a surface, as against submerged, range of 11,000 nautical miles at an economy speed of 12 knots. (The prior Type IXB, a series produced in fewer numbers, had a smaller fuel capacity by 43 tons and a surface range of 8,700 nautical miles.) Propelled on the surface by two 2,200-horsepower diesel engines (ninecylinder, four-cycle, supercharged, salt water-cooled) manufactured by Maschinenfabrik Augsburg-Nürnberg AG (MAN), the IXC was capable of 18.3 knots maximum speed (one knot was one nautical mile per hour, about 1.15 statute miles per hour); and it was on the surface,
which surprises many modern readers, that U-boats of this period did most of their travel and fighting: The submerged attack by periscope was an exception rather than the rule. In truth, because it could not operate continually under water, the 1943 U-boat was a submersible rather than a genuine submarine. It launched its torpedoes in the manner of a motor torpedo boat, and dived only to avoid enemy ships and planes, to find relief from rough weather, or to make an occasional submerged attack in daylight. Submerged, it could make 7.3 knots maximum (except that in U-515’s case, top speed tested out at 7.46), which greatly reduced its maneuverability and effectiveness, particularly in convoy battles.
⁵

Underwater propulsion was provided by twin electric dynamotors
(E-Maschinen),
manufactured by Siemens-Schuckertwerke AG, each rated at 500 horsepower. Power was supplied by sixty tons of storage battery arrays distributed under the interior deck plates. Even at economy speed of four knots, a submerged boat would exhaust its battery power after 64 nautical miles (one nautical mile was about 1.15 statute miles). By clutching a diesel to a dynamotor, which served as a generator, the batteries could be recharged, but that lengthy procedure required that the boat surface. Another kind of power transfer was supplied by compressed air, the product of either diesel-driven Junkers air compressors or an electric compressor that the crew employed for blowing water from the ballast, or diving, tanks when the boat surfaced; for starting the diesels; and for launching torpedoes from their tubes. Like the storage batteries, the compressed air tanks were “topped up” each time the boat surfaced.

In exterior appearance the IXC had the general form of any other boat or ship. It presented a sharp-edged stem at the bow, a rounded hull, a flat upper deck bisected by a superstructure, in this case a conning tower, and a stern. The outer steel casing visible to the eye, which also enclosed the fuel bunkers and the ballast tanks, made the hull more efficient for surface travel. The heart of the U-boat’s architecture, however, could not be seen: it was the pressure hull, a long, narrow, cylindrical tube constructed of welded high-tensile steel plates 18.5 millimeters thick. This structure, resistant to fifteen atmospheres of water
pressure when submerged, enclosed the U-boat’s crew and its engines, motors, compressors, controls, and torpedoes. The normal crew list of a Type IX included four officers and forty-four ratings, but occasionally, on particularly long patrols, the complement would be increased by one or two officers, additional ratings, and perhaps a cameraman-correspondent from the official news service
Propaganda-Kompanie
or a physician. In those cases, the interior of the boat on departure, already constricted by food stores and reserve torpedoes, would be so cramped as almost to prevent human movement.

While the IX boats had the distinct advantage of long-range war waging, and while they performed well against independently sailing or weakly escorted vessels in distant coastal waters, where, in fact, the IXB sank more tonnage
per boat
than did any other U-boat type in the war, and individual IX boats became the third through sixth most productive of the war, they were at a marked disadvantage in the heavily escorted transatlantic sea lanes, where Britain’s seaborne trade moved in tight convoy columns protected by Royal Navy close escorts— destroyers, sloops, frigates, and corvettes—as well as by aircraft, both land-based and, from March 1943, escort carrier-based. The IXs had several particular problems that made them less suitable for convoy operations than another U-boat type that was three times more numerous in the Atlantic at this date, namely, the Type VII.

How well-regarded this latter type was by Dönitz and his boat commanders in convoy operations is evidenced by the fact that prior to and during the war 709 VIIs were manufactured and delivered to the U-Bootwaffe (as against 159 IXAs, IXBs, IXCs, and IXC/405), of which 665 were VIICs or VIIC/415. Produced in greater numbers than any other design in submarine history, the VIIC boat was arguably the best-integrated combat system developed by German engineers prior to the Type XXI, described later. Smaller than the IX, with a lower silhouette, more maneuverable both on the surface and underwater, the whippetlike VII dived faster than the IX, putting 13 meters (42.6 feet) of water above the hull in thirty seconds, while the larger IX required thirty-five seconds at best to do the same. As has been calculated, during that five seconds’ difference an Allied anti-submarine aircraft such
as a Consolidated B-24 Liberator could close a target more than a third of a mile on a depth-bomb attack.
⁶
Furthermore, underwater, the VII boats were more stable in maintaining depth and, because of their smaller size, were less easily located by British detection gear.

During March and April 1943 it was observed by BdU (U-Boat Headquarters) that the losses of IX boats to Allied escorts in the Atlantic was proportionately much higher than the losses of VIIs, leading to a decision on 5 May: “Type IXC boats leaving French ports are to be detailed to remote western or southern operational areas.”
⁷
The same observation explains why it was such a radical step a month before, on 6 April, for BdU to direct IXs “to proceed to the North Atlantic in order to make up the number of U-boats needed there to intercept convoys”; and why the commitment of those resources had to be quickly reversed: though making up less than a quarter of the Atlantic force in April, the IXs suffered twice as many losses (8 to 4) as did the VIIs.
⁸
Never enthusiastic about the IXs as a U-boat type, Dönitz had energetically opposed the construction figures that the Naval Staff in Berlin had advanced for them. Nonetheless, during the January-July 1942 offensive off the American coast (chapter 3) he had to have been thankful that he had as many IXs as he did, for the longdistance boats accounted for two-thirds of the merchant traffic sunk in those waters.