Codebreakers Victory (34 page)

With the integration of these Americans into the Ultra program in late 1943 and early 1944, the promise of effective Anglo-American collaboration could be said, despite a continuance of much bickering and internecine suspicion, to have been, very belatedly, fulfilled.

 

 

6811: Interceptors of Axis Radio Traffic

 

The process of signals intelligence begins with interception. Radio operators must tune in to the rush of Morse
dit-dah
symbols and meticulously copy them down so that the texts cryptanalysts read are as free as possible of skips and garbles. Even for the most dedicated and experienced operators, the copying of Axis radio traffic in World War II posed a demanding test. Enemy transmitters deliberately used only enough power to reach the farthest station in their network. Allied radio ops trying to listen in from well outside the receiving loop had to strain to catch what they weren't meant to hear. Frequently the stream of Morse they were assigned to copy was only the thinnest thread of sound to be picked out amid a welter of booming senders closer in.

"The intercepts had to be fought for, in a battle of skills, wits and wills," British intercept operator Joan Nicholls has reported in her self-published book about her life at Britain's Beaumanor station. "The Germans were adept at placing obstacles in the way of the eavesdroppers." The obstacles included screening transmissions with "what sounded like military bands, operatic arias, Wagner and speech, all played backwards and at high speed. It sounded like hell let loose in our ears, and underneath it all were the faint sounds of our station." Wavering signals and weather interference could make the job still tougher. A GI operator said it was like going to a noisy cocktail party and trying to listen in on a whispered conversation on the far side of the room.

The Americans had to struggle against the impression of being Johnny-come-latelies. Before the GIs ever arrived, the British network of intercept stations, mostly operated by young women like Joan Nicholls, were doing very well, thank you, without a bunch of Yanks getting into their act. The 7 officers and 195 enlisted men of the 6811th were asked to establish and operate an additional station, which the British labeled Santa Fe. While U.S. help was no doubt useful in covering the widening range of German networks, there was always the feeling among the troops of Santa Fe, of which I was one, that we were added as a courtesy.

To house the station, the Yanks were given an ancient manor, Hall Place, in Bexley, Kent, on the southeastern edge of London. Hall Place was a crumbling relic with some of its walls shored up against collapse. In its cold, drafty interior, whose medieval ceilings seemed to push down on us better-nutritioned Yank residents, the dining hall was converted into a Set Room, with banks of gray-metal Hallicrafters receivers lined up on plank tables. The detachment included one group of radio operators newly trained in the U.S. and a more experienced group transferred from the intercept station they had been manning in Newfoundland.

Santa Fe went into operation on a round-the-clock three-shift basis beginning March 1, 1944. The British assigned it some twenty-five German networks to cover, mostly German air force nets. Many, if not all, of these they were already covering. Redundancy in intercept, we were to learn, is not a waste, since in this game, in which accuracy is needed so acutely, a second operator may correctly copy a signal that the first one partially or wholly missed.

To be assigned a Luftwaffe network meant that the 6811th interceptor had to copy every message sent by all the operators on that net, with the German ops often impatiently waiting their turn. The result was that the Yank was likely to emerge after an eight-hour shift with shaking hands and bloodshot eyes, badly in need of a pint in the nearest pub.

To each shift of radio ops in the Set Room was added a team of eight men rudimentally trained as "cryptographers." Any fantasies the cryptographers harbored of actually breaking significant enemy messages, with generals anxiously awaiting the decrypts, ran up against the reality of our identifying nomenclature: we were the CRR teams, for "Compilation of Reports and Records."

In fact, because of the limitations of the "need to know," the common soldiers at Santa Fe never learned whether the masses of five-letter code transmissions the radio ops received and the cryptographers processed were ever broken. The outfit settled into the routine of handling endless yards of gibberish and making sure that each unit of it was accurately filled in and correctly identified as to time, network and frequency, without ever knowing the content of any of it.

In addition to the radio operators and us cryptographers, each of the shifts also included a small team of Teletype operators who forwarded the intercepts by landline to "Station X"—in actuality, Bletchley Park. On the telephone links to British intercept stations and to X, the fine female British voices oozed condescension toward us late-come Americans.

To do our job, we cryptographers did need to know one important secret. This we summed up in three words: "predicted call signs." In military radio the senders of coded messages try to obstruct interceptors as well as codebreakers. One of the ways they do this is by regularly changing the letters identifying their stations. Unlike commercial radio stations, which want to be recognized as WOR or WLW, military senders try to leave interceptors floundering uselessly in the ether by abruptly switching to a different frequency and employing a whole new set of call signs. What was ABC on 4031 kilocycles suddenly becomes XYZ on 2778 kilocycles.

For their systems the Germans devised fat books of call letters, forty thousand three-letter call signs to a book. At changeover times, usually shortly after midnight, the German ops were armed with a daily numerical shift. The shift told them where to move forward or backward in the call sign books to arrive at their new rows of call letters.

By the time the 6811th set up shop, the British had this whole call sign mechanism completely pinned down. Santa Fe was supplied with the "Elephant" book, which meant that it was the fifth in the series. It hadn't simply been captured somewhere; it had been compiled by infinitely patient analysts. It had blanks in it that were filled in as new call sign lists and placement coordinates came down from X.

The significance of predicted call signs was clear. If a German spy should hear any reference to the prediction, the result could be calamitous. He would know that the German system had been compromised, and if that phase of it was broken, he could arouse suspicions that the whole German encoding superstructure was breached. Many of us had nightmares in which we had one too many glasses of bitters in a pub and blurted out our most closely guarded secret in the presence of a German agent.

The kind of minuscule contributions the Yank cryptographers were able to make is exemplified by one that I recall as probably my singly most important deed of the war. It came on a day in March 1945. At that late date, with the war collapsing around them, the Germans managed to do what they had not done earlier: they made a clean break to a whole new call sign and frequency system. Suddenly everything in the radio spectrum was chaos. The German networks weren't at their usual frequencies, and what was by then the
F
book was dead without anything to replace it. The CRR could no longer provide predicted call signs. Each radio operator went on search, trying to find his network by detecting the sending idiosyncrasies of one or more of his German transmitters. In preparation for this moment, we and our operators had been boning up for days on any distinguishing quirks of the nets assigned to Santa Fe.

I was leaning over the shelf beyond which Jim Hammet, one of our brighter operators, was twiddling his dials trying to latch on to something recognizable. "That's funny," he said.

"What's funny?" I asked.

"This net leaves a space between the first three letters and the last three letters of the indicator. See this:
ARZ
space
DLY.
That's different from my net. They run all six letters together without a pause."

Excitement swelled within me. "We have only one network that does that. Benny Abruzzo's. Give me the frequency and a couple of the call signs and let me have Benny check it out."

I carried my slip of paper to Benny's set. He turned his tuning dial with the delicacy of a safecracker. His face lit up. "That's him! That's one of my guys! I'd know that Heinie meat fist anytime, anywhere!" He grabbed his pad and pencil and began happily copying.

So we three pinned down one frequency and one set of call signs for one day of that one net's operation. It was just such small victories, endlessly accumulated at Station X and fitted like pieces in a giant jigsaw puzzle, that helped the geniuses crack the Germans' systems.

It did seem to me, when I reported our find to Station X, that the British female voice at the other end of the line was, this time, not quite so patronizing.

Other than for moments like this, the work was tedious in the extreme. Even so, everyone in the 6811th went at his tasks with one thought ever in mind: that this message, or the next one, or the one after that, could, when broken, make the difference for some soldier or sailor or airman, perhaps for a whole contingent of soldiers or sailors or airmen, out there on the fighting front. Any examples of surrender to ennui were few and far between.

The prevailing attitude can best be characterized by an incident in September 1944 when Hitler began sending over his V-2 rockets. One hit so close one day that it broke out windows and brought down a ceiling or two in the manse. A radio operator named Arthur Koester, a T/5 corporal, was at work copying his net when the frame of a window above him was ripped out and hurled on top of him. The wood and glass tore a gash in his head, sending blood coursing down over his face. Koester never stopped copying. Sergeant Vernon Pemberton, the Set Room chief, quickly had another op tune to Koester's net and begin copying the same traffic. Then he yelled at Koester, "You can break off now, Art. We've got your net covered." Koester just waved him away. "Come on now, Art," the sergeant pleaded. "Break if off so we can start taking care of you." Koester simply growled and set himself more firmly. Finally the sergeant grabbed Koester's pad and jerked it from under his hands. Koester shot to his feet, shouting at his NCO, "You stupid son of a bitch. Can't you see I'm copying?"

Art was one of two Purple Heart recipients in the 6811th. Our captain was so craven for recognition of the unit that he refused to distinguish between Koester's deserving wound and that of another GI who was hurt when a V-2 hit near the house in which he was shacked up with his British girlfriend.

 

 

6812: Operators of the Bombes

 

Bletchley Park relied on members of the Wrens to operate the bombes used to determine Enigma key settings. As the number of the Germans' Enigma-based ciphers increased, so did the numbers of bombes needed. At the peak, nearly two thousand Wrens were operating the bombes round the clock. For the women it was heavy going. Petty Officer Diana Payne subsequently recalled work on "the monster deciphering machines" as "soul-destroying but vital." After many months of this merciless routine, the strain began to show. As Payne reported, one Wren collapsed, rendered unconscious by overstrain. Another began to have nightmares from which she woke up desperately clutching a phantom drum of the sort she had been loading onto the bombes day after day. A girl who was due to have an operation became frantic with the thought that under the effects of the anesthetic she might give way and talk.

When in early 1944 fresh cadres of Americans began to move into that comer of Britain to help operate the bombes, their arrival was most welcome. These were the men of the 6812th Signal Service Detachment, 5 officers and 149 enlisted men. Whoever was doing the code-naming of the American outfits must have been a railway buff. The name for this unit was Rock Island. The troops were billeted on the northwest outskirts of London until they could get their own camp built, partly by their own labor, in the Middlesex town of Eastcote. Their three-shift work assignment was to operate an array of bombes in a building they called the Factory. They were close enough to London to be on the receiving end of a few V-weapons that overshot their target, but far enough away from Bletchley Park that they never went there and knew of its existence only via phone lines and teleprinter links. Here, too, the "need to know" limited the GIs from learning definitely that the messages on which they worked were ever broken. "We did what we were told," Paul Best of the detachment remembered later, "and had to take it on faith that our work was being effective in helping to solve the German messages."

Their orders came from Bletchley Park in the form of "menus" instructing them what to do. As Best explained,

 

Each drum of a bombe was an analogue of a rotor of the Enigma machine, with 26 letter positions on each drum. BP would send us a menu based on a crib of a German phrase that they hoped would be found in the message. The operator would place the drums on the bombe in the order specified by BP, turn them to the menu positions, plug in the cables at the rear, again according to the menu instructions, and switch on the machine. Essentially we were seeking a yes-or-no answer as to whether the crib was actually a part of the message. If the answer was no, we would keep the bombe running through its fifteen-to-twenty minute cycle and nothing would happen. We would call BP and report, "Sorry, that menu was no good." But if there was a "hit," the bombe would hunt for a voltage that indicated a circuit closing and would stop. We would note all the rotor positions and set up our replica of an Enigma machine in those positions to test whether the hit was confirmed. Then we would send the confirmation back to BP and wait for our next menu. With all that array of bombes in the Factory, we could check out hundreds, thousands, of possible cribs in a single day.

 

As with the men of the 6811th, those of the 6812th were haunted by their secret knowledge. "It was a load to carry," Best recalled. "Here we were, operating replicas of the Germans' encoding machines and, what's more, also operating the still more complex machines that, we felt sure, were being used to conquer the German machines. We dreaded the possibility of one of us going off his rocker and being unable to hold it in any longer. It never happened, but the possibility hung over us like an inescapable cloud."