Black May

Michael Gannon

• Publisher: Harper
• Year: 2011
• ISBN:
  9780062039460
• Topic: Histoire
• Subtopic: Seconde Guerre mondiale

In May 1943, Allied sea and air forces won a stunning, dramatic, and vital victory over the largest and most powerful submarine force ever sent to sea, sinking forty-one German U-boats and damaging thirty-seven others. It was the forty-fifth month of World War II, and by the end of May the Germans were forced to acknowledge defeat and recall almost all of their remaining U-boats from the major traffic lanes of the North Atlantic. At U-Boat Headquarters in Berlin, despondent naval officers spoke of "Black May." It was a defeat from which the German U-boat fleet never recovered.

Black May is a triumph of scholarship and narrative, an important work of history, and a great sea story. Acclaimed historian Michael Gannon, author of Operation Drumbeat, has done enormous research and produced the most thoroughly documented study ever done of these battles. In his compelling historical saga, the people are as significant as the technical information.

Given the strategic importance of the events of May 1943, it is natural to ask, How did Black May happen and why? Who or what was responsible? Were new Allied tactics adopted or new weapons employed?

This book answers those questions and many others. Drawing on original documents in German, British, U.S., and Canadian archives, as well as interviews with surviving participants, Gannon describes the exciting sea and air battles, frequently taking the reader inside the U-boats themselves, aboard British warships, onto the decks of torpedoed merchant ships, and into the cockpits of British and U.S. aircraft.

Throughout, Gannon tells the Black May story from both the German and Allied perspectives, often using the actual words of captains and crews. Finally, he allows the reader to "listen in" on secretly recorded conversations of captured U-boat men in POW quarters during that same incredible month, giving intimate and moving access to the thoughts and emotions of seamen that is unparalleled in naval literature. Rarely, if ever, has the U-boat war been presented so accurately, so graphically, and so personally as in Black May.

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 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):

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 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.

Essentially, a U-boat’s pressure hull existed as a weapons platform, that is, as a means for delivering to the enemy, sometimes overtly, sometimes in stealth, a considerable destructive threat. Although a IXC like U—515 carried two deck guns on its upper casing, a 10.5 cm forward and a 3.7 cm aft, as well as one or two 20mm anti-aircraft guns on a platform aft of the conning tower, and although some boats (notably the IXB U-123) had sunk shipping with gunfire alone, the World War II U-boat’s main armament was always the torpedo.⁹ A IXC could carry as many as twenty-two torpedoes. Normal stowage on a Feindfahrt (operational patrol) was fifteen to seventeen. These cigar-shaped weapons would be stored as action-ready in the launch tubes, of which the IXC had six, four bow and two stern, and as reserves under and over floor plates or in chains or cradles that temporarily displaced sleeping bunks in the fore and aft torpedo rooms.

Additional stowage was provided by six containers under wood slats between the pressure hull and the upper deck casing, but by 1943 U-boats rarely used them because of the length of time it required the crew to winch a torpedo down the open forward hatch, a period during which the boat was critically vulnerable. Concern was spreading by April 1943 that the Allies possessed new, more powerful depth charges, as evidenced by increased cases of damage to the upper deck containers. Should those containers fracture and fill with water, and should weight thereby suddenly increase to offset the trim, a submerged U-boat could fall fatally out of control. For this reason, as well as for the fact that the now constant danger of air attack had deterred boats from reloading at sea, BdU ordered all boats of whatever type preparing to...