Operation Drumbeat
Page 20
2340. F.T. intercepted, V-701 in BC south of Greenland to BdU: Second Watch Officer Lieutenant Weinitschke lost overboard today at 1849.24
Then, on 2 January at 0400 hours, dots and dashes addressed to U-/23 filled Barth’s earphones and notepad. Except for Christmas greetings from Admiral Dönitz and New Year’s felicitations from Admiral Raeder, this was the first signal to the boat that either Barth or Rafalski had received on their watches. When the Schlüssel M decrypt revealed the first word in the transmission to be Offizier— “officer”—meaning that only Hardegen or another officer could continue with the signal, Barth called for Hoffmann who took the cipher machine and the signal to the wardroom table and began punching out the decryption:
OFFICER. TO HARDEGEN U-123. ON 1 JANUARY EVENING IN SQUARE BC 4335 GREEK SHIP DIMITRIOS INGLESSIS REQUESTED TUG ASSISTANCE OWING TO DAMAGED RUDDER. YOU MAY ATTACK IF NOT FARTHER THAN 150 MILES FROM POSITION GIVEN. BDU OPS.25
Hoffmann crossed over to Hardegen’s bunk and roused the commander from sleep. Within seconds the two men were huddled under the lamp over Kaeding’s grid chart computing distances and times and checking out the Greek vessel in Gröner.
“She’s 5,275 GRT, Herr Kaleu,” said Hoffmann, putting Gröner back on the shelf.
“Not exactly a ten-thousand-tonner,” answered Hardegen. “But since BdU says we can have her, I’d like to go for it. The problem is the distance. BdU says we can attack if the target is within 150 miles. But the Greek position is 360 miles, somewhat to the northwest, approximately here”—he pointed to Virgin Rocks on the Grand Banks where the least depth was 6.75 meters (fourteen feet) over rock. “I don’t know. Let’s keep steady on 270, both engines at three hundred RPM, and see what develops.”
At 1745 hours the next day, following another practice drill underwater, a second signal from BdU arrived. This time the message was more detailed. St. John’s had sent a rescue tug, Foundation Franklin, out of Halifax, to assist the Greek ship, which had been part of convoy SC 63. The rudder damage had resulted from a fierce sea storm. If the tempest permitted Foundation Franklin should be on the scene by 5 January.26 At 1800 Hardegen made his decision. Even though it meant a fuel loss, and even though it meant disobeying BdU, which he had done once before with great success in the Aurania attack, he determined to catch this wounded prey and add her to his bag. Rafalski picked up an SOS directly from Dimitrios on the six-hundred-meter band: RUDDER LOST X NEED HELP IMMEDIATELY X APPROXIMATE LOCATION 48-39 N, 48-21 w.27 At 2000 hours Hardegen and Kaeding calculated that from U-/23′s current position at BC 6143 they could intercept Dimitrios on a steered course of 283 degrees. Hardegen gave the order to the helmsman and directed the engine telegraphs: “Both ahead full!”
At 1530 on 4 January Rafalski and Barth were able to report that the Greek steamer was transmitting directional signals to the recovery vessel. With a cross bearing off St. John’s, Hardegen now figured the Greek’s position at 310 degrees in approximately BC 2746. He joined von Schroeter and the bridge watch in the visual search. A fog that had hampered visibility lifted for a brief while and the glasses could reach ten miles. Then, gradually, the fog closed in again and visibility went down to two hundred meters. Barth and Rafalski stayed busy below, taking directional bearings and monitoring the six-hundred-meter transmissions that passed from Dimitrios to Foundation Franklin to St. John’s. Rafalski called up the pipe: “They’re talking about various means of towing. The salvage vessel will reach the position at 2200.” Now a second ship asked for a bearing, Rafalski reported, and a signal was agreed upon: the stricken steamer would give two blasts on her whistle. At 2256 Hardegen heard a foghorn ahead. He ordered the gun crew to battle stations.
“Both ahead slow.”
Now there were two different foghorns, very close. In the darkness and fog the watch could see nothing during the next thirty minutes of approach. Then, at 2338, a lookout shouted, “Two lights, weak, port ten!” Hardegen peered through his 7 x 50s and confirmed the sighting. That had to be the steamer and the rescue vessel. But two additional foghorns now sounded in the night. Did we have more ships about than these two?
“Shut down both engines!” he ordered the helmsman. To the sound room he called: “Puster, try to get a count on propellers.” As the boat lay to and bounced quietly from trough to wave at steerageway, Barth in his sound room wheeled back and forth across the compass card examining the hydrophone effect produced by propeller cavitation—the partial vacuum that forms and collapses about rapidly revolving blades. At 305 degrees he picked up the familiar thump-thump-thump of a commercial steamer, but its higher-than-normal pitch suggested a tugboat. He reported to Hardegen: “HE bearing Red three-zero-five, Herr Kaleu. One small steamer, probably a tug.” Crossing 360 degrees to the Green side of the compass, Barth froze as he detected two slightly different sources, mixed, that resembled if they were not in fact the dreaded swish-swish-swish of—“Destroyers, Herr Kaleu! Two in number, bearing Green zero zero four and zero zero six!” Barth was not certain but he would rather be wrong than dead. “Ranges—.”
On the bridge Hardegen did not wait for the ranges: “Diesels, both back emergency full! Rudder amidships! Open bow caps, prepare tubes one, two, and four! Gun crew below! Rig for dive!” At just that instant he saw looming before him, not one hundred meters ahead, a large shadow, no doubt the steamer, from which a white blinker light was signaling in Morse. Another smaller shadow now plodded slowly abeam the steamer. Hardegen followed it with his glasses and identified it as a two-stack oceangoing tug. He thought of turning 123 for a bow shot at the large shadow, but as the rudder worked the turn the fog suddenly lifted and moonlight filled the seascape, illuminating the shadow, which turned out not to be the helplessly drifting steamer but a destroyer! He had been within a soccer field’s length of a destroyer!
Another destroyer lay five hundred meters off at starboard fifteen, rising and falling on the now-silver water. It was a good thing, Hardegen reflected with a shake of the head, that he had not opened fire with his gun. Eins Zwei Drei would have been no match for the barrels of two destroyers. As 123 disengaged, Dimitrios and Foundation Franklin came into view passing lines preparatory to towing. Hardegen held his breath as 123 backed out of the moonlight. So far, lookouts on both destroyers had failed to detect his nap-of-the-water silhouette. The security of fog finally embraced the boat, and, killing sternway, Hardegen struggled to decide what was his best course of action. While he pondered, the tug took storm-battered Dimitrios in tow and set out slowly toward St. John’s 450 miles away on a course of three hundred degrees. The two destroyers took positions astern. Should 123 advance and attempt torpedo launches at the steamer and both destroyers? Or at the steamer alone? A submerged attack was out of the question: Despite the nearly full moon it was too dark for the attack periscope, which had poor light transmission qualities. He considered a surface attack. The problems here were several. First, because of the now-bright moonlight, he would have to launch from a great distance out, reducing accuracy. Second, he would have to go for the destroyers first—Dimitrios and the tug not being able to escape or do him harm—and from a distance the destroyers presented small, frisky targets; success was doubtful. Third, the fathometer in the control room was showing only sixty meters’ depth under the hull, which meant no escape from depth charges should the torpedoes miss and even one destroyer bring her ASDIC to bear. Fourth, he should be saving his torpedoes for “Drumbeat.” As this line of reasoning reached its end, a deep fog swirled in again. With visibility down to one-to-two-hundred meters, new circumstances made the question of attack moot. Such, one could say, was the nature of naval warfare in the wintry North Atlantic.
That was not what Reinhard Hardegen would say. In composing his war diary during the next hour and a half he reproached himself bitterly for not having attacked at all. “Attack, Advance, Sink!” were the words of the Lion. Hardegen had failed for the first time in his naval career to pursue an enemy, attack him aggressively, and sink him
if possible. To the KTB he confessed: “Fundamentally, my behavior has certainly been wrong. I uselessly expended six cubic meters [1,600 gallons] of fuel. Only the coming weeks will disclose if my decisions are justified by ‘Drumbeat.’”28
Deciding that he would never again permit this kind of ambivalence to develop, Hardegen determined that the next time imponderables threatened to overcome clean, direct military action he would attack first, at once, decisively, and let history sort out the consequences. Timidity, which is how he characterized his balancing of options and dangers, would never again cast an enervating spell over 123. To hazards he would henceforth be indifferent. As boat and crew resumed their course for the United States, the commander braced his shoulders and hardened his face for the stern errand ahead.
* See Appendix C.
6
Waiting for Hardegen
1100 hours, 2 January 1942. In the coastal township of Flowerdown near Winchester in southern England a motorcycle dispatch rider in battle dress sat lazily atop his Matchless G3L motorcycle waiting for a member of the Women’s Royal Naval Service (WRNS) to bring him his packet. Towering above the Y Station hut where the Wrens worked were three rectangular radio antennas. The dispatch rider had no idea what the antennas were receiving. Neither, for that matter, did the Wrens, whose finely trained ears, plugged into RCA AR 88 superheterodyne communications receivers with interference-cutting crystal gates, were in intimate, though hardly affectionate, contact with hundreds of German shortwave Morse senders, the fastest keyers in the world. The Wrens knew many of them as soon as their transmissions began, whether from stations on land or at sea, for each of them had his own distinctive keying style, or “fist.” The BdU fists were unmistakable, like old family friends. And some of the U-boat senders, too, who had been at sea on numerous patrols, came into Flowerdown like regular club members. The Wrens gave them names like Handlebar, Wagner, Menjou, or Moselle. Where they were surprised by a new, idiosyncratic fist they ran a recording of the signal on an oscillograph that provided an operator signature called TINA. By RFP, or radio fingerprinting, they could identify a transmitter and its power supply. And by triangulating with other Y Service stations at Scarborough on the east coast and at Hvalfjord, Iceland, they could establish the intersection, or “cuts,” of bearing lines and acquire a generally good “fix”—sometimes within a dozen miles, more often within thirty to fifty miles—of a given transmitter’s geographical location. The system, called High Frequency/Direction Finding (HF/DF, or “Huff Duff”), zeroed in on a shortwave transmission from the moment the first dot or dash left the operator’s hand. Not a boat at sea escaped the Wrens’ net. What did escape them was the meaning of the intercepted signals. It would have been nice to know what Handlebar and Wagner were saying. But the five-letter groups were all gobbledygook to the Wrens as they prepared the sheaves of papers for the forenoon dispatch packet.
With the packet in its waterproof case slung across his shoulders, the rider kicked his starter and set out with a racket on country roads north through Hampshire and Berkshire Downs to Newbury, Oxford, and Stony Stratford. After four hours of riding, which he was under orders not to interrupt for any reason including calls of nature, he entered the outskirts of a Buckinghamshire railway-junction town called Bletchley, some fifty miles northwest of London and halfway between Oxford and Cambridge. Follow ing its narrow streets he came to a guard gate outside a red-brick mansion in pseudo-Tudor-Gothic style with manicured lawns and a swan pond. The place was called Bletchley Park, though since 1939 the edifice itself had assumed the name—mostly fictitious—Government Code and Cipher School, GC & CS, called also BP or, by code name, Station X. After passing sentry inspection, the rider wound around to the back of the building, where thousands of men and women, in and out of the military services, worked around the clock in single-story white-frame Nissen huts that were scattered about the spacious grounds. His destination was Hut 8. There he handed his packet to the duty officer, signed the dispatch ledger, and headed for the WC and kitchen in the sentries’ canteen. In two hours he would be on the road back to Flowerdown.
Inside Hut 8 the duty officer passed the packet of intercepts to the Wren in charge of naval cryptanalysis on the afternoon watch. She, in turn, assisted by a battery of other servicewomen, copied the intercepts, signal by signal, onto tapes and fed them into an eight-foot-tall “copper-colored cupboard” called “Bombe.” At Bletchley Park (BP) the German Schlüssel cryptographic machine (as well as its product) was called “Enigma”: the Bombe was an electromagnetic scanning machine constructed from a series of Enigmas yoked together. The Bombe had been conceived in 1934 by Polish Intelligence Service mathematicians who were in possession of an early model of the German-invented Schlüssel and had contrived with partial success to defeat it. Only months prior to Hitler’s invasion of Poland, they had passed on two copies of the basic machine to French and British Intelligence together with plans, drawings, and instructions to explain how their yoked series of six machines could explore the Enigma’s range of alphabet and word possibilities far faster than the pace of human thought. At BP a young, eccentric Cambridge mathematician named Alan Turing, who had long been devoted to the theory of a universal calculating machine, made an original contribution that greatly increased the power of the Bombe. Though electromechanical rather than electronic, Turing’s brilliant design anticipated the modern computer. By April 1940 the “copper-coloured oracle of Bletchley” spoke. First to shed its veils was Luftwaffe Enigma traffic, owing to its low-grade operators and slack communications discipline. Shortly afterward, Wehrmacht Enigma yielded to the penetrations of the Bombe, which rendered the five-letter cipher groups into their original German message forms. Reading was not always current: Sometimes 72 hours would pass before BP could produce a passable text, sometimes the process would take a week, and sometimes the Bombe failed altogether; except that BP could always count on the Luftwaffe’s key for the day being available by breakfast.1 Having the key, which meant having the rotor settings and the plug pairings for a given twenty-four-hour period, was the essential requirement if BP was to be able to read the W/T intercepts with any regularity. And that was why naval Enigma was the last to submit.
Kriegsmarine cipher discipline was the tightest of any in the German armed forces. The Ubootwaffe was particularly security conscious and had made a number of complicating modifications in the machine. The result was that for a long time U-boat HYDRA (which BP called DOLPHIN) was invulnerable. What BP needed was a full or current HYDRA handbook giving settings and pairings, and that meant a capture, or, as the British liked to say, a “pinch.” On 23 February 1941, during a commando raid on the Norwegian Lofoten Islands, a Royal Navy boarding party discovered spare Schlüssel-M rotors, though no machine, on the abandoned German trawler Krebs. By March 1941, BP was reading much of HYDRA but with a month’s lag time, too great for the data to be of operational value. Then, on 7 May, in a tightly planned operation, boarding parties of the Royal Navy captured cipher material from the German weather ship München. Two days later, in an even more dramatic and critical pinch, three warships escorting convoy OB 318 southeast of Greenland depth-charged and crippled U-l 10, commanded by Kptlt. Fritz-Julius Lemp, notorious as the sinker of the Donaldson liner Athenia on the first day of war and one of two commanders—Hardegen being the other—known to have been required by Admiral Dönitz to falsify a KTB. To Lemp and his crew, as their boat lay helpless on the surface, the British called out: “Boot hoch halten, sonst wird keiner gerettet!”— “Keep your boat afloat or no one will be rescued!” Gas fumes drove Lemp and the panicking U-boat crew into the water, where all but Lemp were picked up and taken below by the secrecy-sensitive warship captains. As for Lemp, he attempted to swim back to 110 and scuttle her but was shot dead as he clambered onto the deck. In 1 W’s interior a boarding party discovered her Schlüssel M with spare rotors; HYDRA handbook with daily settings and pairings and special settings for officer-only signals, all valid to the end
of June; short-signal position codes; and other confidential papers. Heavily guarded, the godsend was transported at flank speed to home port, and thence to BP, where the capture was quickly recognized as one of the decisive intelligence breakthroughs of the war to date. Within days BP was reading naval Enigma much closer to the grain.2
Between 25 May and 21 June, BP supplied the position coordinates from Enigma that enabled warships to destroy seven of the eight German supply ships that had been posted at various points in the Atlantic to assist Bismarck, Prinz Eugen, and operational U-boats. Wary lest such a wide-ranging roundup be taken by the Germans as more than coincidence, the Admiralty backed off from further grand slams and concentrated instead on evasive routing of convoys from known positions of boats and patrol lines. One of the first examples of Enigma-assisted diversions occurred on 23 June when BP warned that ten U-boats lay athwart the route of Britain-bound convoy HX 133. From that date throughout 1941 and into early 1942, BP supplied enemy information that led to an ever-decreasing number of sinkings in t he established convoy lanes of the North Atlantic, off Gibraltar, and in the Mediterranean.3 Only the short-signal position reports after November caused serious cryptanalytical problems and delays owing to Dönitz’s Adressbuch, which, still unresolved by Turing’s Bombe, required continuous ad hoc research.
Now on 2 January the Wrens who served the engine patiently watched its front wheels spinning and listened to its innards—clickety-click, clickety-click, like a knitting machine—as for hours the device considered one possible setting/connection after another seeking the one mathematically elusive combination that fitted a prescribed group of letters. Suddenly the machine stopped. A printer engaged. An elated Wren, sensing personal triumph, drew out a printed text on tape. From Wren to Wren the text made its way thirty yards outdoors to Hut 4, Naval Section, where it came under the care and scrutiny of a donnish group of men, mostly civilians recruited from nearby Oxford and Cambridge. Linguists, logicians, classical scholars, they formed the translating and intelligence-processing watch for all Kriegsmarine signals. Combining an exact and comprehensive knowledge of German with a newly acquired mastery of U-boat and surface-ship technology, nautical terms, and military abbreviations, the twelve-man watch sat around a bare horseshoe table in a forty-by-forty-foot room, where the number one of the watch, seated in the middle of the horseshoe, assigned decrypts for translating. The latest example presented no problems. Very quickly one of the dons joined or separated the German five-letter groups to form words, phrases, and sentences, translated the result into English, and handed the result to the number one, who inspected first the reconstructed German text and then its English rendering: OFFICER, TO HARDEGEN 11-123. ON 1 JANUARY EVENING IN SQUARE WRANGELSTRASSE 1 587 GREEK SHIP DIMITRIOS INGLESSIS REQUESTED TUG ASSISTANCE OWING TO DAMAGED RUDDER. YOU MAY ATTACK IF NOT FARTHER THAN 150 MILES FROM POSITION GIVEN. BDU OPS.