Black May

by Michael Gannon

  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?

  I would like to say yes and no, because a lot of good friends of ours had gone down and had been lost. But, on the other hand, we had our duty. We had been in a war, in a world war; we had been soldiers, and we had to do our duty. I could imagine on our side in the minds of the Commanders there was some uncertainty because of the losses. They didn’t know what weapons the enemy had at hand, therefore they may have been more reluctant on pressing, on getting through. As for pessimism expressed in conversations with other Commanders at Lorient, I don’t remember such talking, because we more or less avoided talking about those things.18

  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:

  The enemy has based his defensive measures to a considerable extent on their morale effect. The man who allows his healthy warrior and fighter instincts to be hoaxed and humbugged ceases to have any appreciable powers of resistance to present-day enemy defenses. He is no longer capable of attack but feels universally hunted and persecuted.20

  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:

  Submarine warfare is difficult. However, it is obvious that the aim of sinking merchant ships must be to sink more than the enemy can build. If we do not reach this objective, the enemy would continue to suffer severely through loss of his material substance, but we would not be successful in bleeding him to death due to the diminution of his tonnage. I therefore fear that the submarine war will be a failure if we do not sink more ships than the enemy is able to build.22

  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.

  1

  OMENS

  May Day

  Not only must every opportunity to attack be resolutely seized, but it would also be a grave error to depart from the principles which have been hammered into U-boat crews so hard and so frequently: “get to your position ahead just as quickly as you can, launch your attack just as soon as you can, exploit your opportunities at once and as fully as you can.”

  KARL DÖNITZ

  Enemy submarines are to be called U-boats. The term “submarine” is to be reserved for Allied underwater vessels. U-boats are those dastardly villains who sink our ships, while submarines are those gallant and noble craft which sink theirs.

  WINSTON S. CHURCHILL

  THE 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 C
ommander’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):

  Double fan launch [Fächer] from [torpedo] Tubes II and IV. [Torpedo] speed 14 knots, range [to target] 1,200 meters. [Target’s] bows on right, bearing 80 degrees, [torpedo] depth 5 meters, running times 37 and 38 seconds. Two hits amidship and forward [but] the steamer doesn’t sink. Coup de grace [Fangschuss] from [stern] Tube VI, depth [set to run below the keel of the target] 9 meters, [torpedo warhead equipped] with Pi 2 [Pistole-2: a detonator designed to be activated by the magnetic field of a ship’s steel keel], running time 36 seconds. Hit toward the stern, in the engine room—a powerful explosion. The steamer sinks slowly on an even keel, transmits wireless signal. [Another] coup de grace, this time from Tube I. Depth 10 [meters] with Pi 2, running time 25 seconds. Hit forward—great explosion. Ship goes down after about 10 minutes. It’s the California Star at 8,300 GRT, [which was sailing] from New Zealand to England with butter, cheese, lard, and meat. The Second Officer was taken prisoner. The Captain and First Officer probably went down with their ship.2

  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:

  Advanced on a freighter of 3,500 GRT. Double fan launch from [stern] Tubes V and VI. [Target’s] speed 8.5 knots. [Torpedo] depths set to 3 and 4 meters. [Target’s] bows on right bearing 80 degrees. Range 800 meters. [Torpedo] running times 60 and 61 seconds. Hits fore and aft. Ship capsizes and sinks very quickly.3

  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 lau
nching 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.