A Codemaker's War
The Poem CodeConverted for the Web from "A Hard Man to Place," chapter one of "Between Silk and Cyanide: A Codemaker's War, 1941-1945" by Leo Marks
Jump to: Leo Marks Leaves Home | Code-Breaking School
Special Operations Executive (SOE) | Baker Street Code Room | Poem Code
Even SOE knew that for security reasons all messages to and from the field had to be at least 200 letters long -- one more dangerous disadvantage of the poem-code. The country section officers who originated messages had acquired the appalling habit of sending the same text to as many as a dozen different agents with only marginal changes of phrasing.
The poem-code simply couldn't stand up to these mass-produced texts. If the enemy broke one agent's messages they would know what to look for in their other intercepts -- it would be an anagrammer's delight.
I made my first contact with Buckmaster of the French section, Hardy Amies of the Belgian, Hollingsworth of the Danish, Blizzard of the Dutch, Wilson of the Norwegian and Piquet-Wicks of another French section, though I wasn't yet sure why there had to be two. I asked them to paraphrase their messages and free their language whenever possible, and mistook their acquiescence for security-mindedness instead of the quickest way to get me off the telephone.
The next time I held out the begging-bowl on behalf of the infirm poem-code was for a very different ailment, and the remedy was even less to their liking.
To encode a message an agent had to choose five words at random from his poem and give each letter of these words a number. He then used these numbers to jumble and juxtapose his clear text. To let his Home Station know which five words he had chosen, he inserted an indicator-group at the beginning of his message. But if one message was broken -- just one -- the enemy cryptographers could mathematically reconstruct those five words and would at once try to identify their source.
Amongst SOE's best-sellers were Shakespeare, Keats, Tennyson, Molière, Racine, Rabelais, Poe and the Bible.
One agent had been allowed to use the National Anthem, the only verses which he claimed to remember: suppose the enemy broke one of his messages and the five words he'd encoded it on were "our", "gracious", "him", "victorious", "send", then God save the agent. They could sing the rest of the code themselves and read all his future traffic without breaking another message.
Even works less familiar to the Germans than the National Anthem -- the Lord's Prayer perhaps -- would cause them no problems. Reference books are jackboots when used by cryptographers. But if our future poem-codes were original compositions written by members of SOE, no reference books would be of the slightest help in tracing them. Not even Marks & Co.'s.
It would make it slightly more difficult for SOE's messages to be read like daily newspapers if we started a Baker Street poets' corner.
I hadn't thought that writing poetry would be my contribution to Hitler's downfall, but it would at least prevent the Germans from using our traffic for their higher education. Striding up and down the corridors like the Poet Laureate of Signals, I did what I could to make my poems easy to memorize, less easy to anticipate, but I was obliged to turn to the country sections for help with their respective languages. I again telephoned Messrs Buckmaster, Amies, Hollingsworth, Blizzard, Wilson and Piquet-Wicks and asked if they would kindly write some poetry for me in their respective languages.
Rumour began to spread that there was an outbreak of insanity in the Signals directorate.
It was well founded. Agents were making so many mistakes in their coding that breaking their indecipherables single-handed against the clock was like being the only doctor in a hospital full of terminal patients. And the biggest indecipherable of all was SOE itself.
Formal acceptance into the organization had brought me no closer to understanding it. All it had produced was a pass of my own which I could rarely find, and a desk in Owen's office which I rarely left. Although the code room was only a few yards away, I seldom visited it as main-line codes were none of my business. All maimed agents' messages were brought in to me as the girls had neither the time nor the training to mend the fractures.
The prospect of ever being able to form a code-breaking team seemed even more remote when Dansey's foreboding hardened into fact. Ozanne transferred all agents' traffic to the wireless station at Grendon Underwood. The coding was to be done by groups of FANYs (First Aid Nursing Yeomanry). The takeover was to be in August, only a few weeks away. Dansey would still be in charge of agents' codes -- but this could be changed at the flick of a mood-swing. He warned me not to visit Station 53 without the approval of the Gauleiter of Signals.
While grim power-struggles were raging throughout every directorate in SOE, I was engaged in a still grimmer one with Edgar Allan Poe.
He was the favourite author of an officer on Buckmaster's staff named Nick Bodington, who went backwards and forwards to France as if he had a private ferry. For this trip's traffic he'd chosen an extract from "The Raven". Bodington's message was indecipherable and I'd been impaled on the bloody bird's beak for six consecutive hours.
The passage Bodington had chosen was:
While I nodded, nearly napping, suddenly there came a tapping,
If the indicator-group were correct, the five words he'd encoded the message on were: "came", "chamber", "my", "rapping", "door". When I tried decoding it on these five, all that emerged was the Raven's cackle.
Some 3,000 attempts later I discovered that the indicator was correct and the coding perfect. All Bodington had done was omit a "p" from "rapping", which turned it into "raping" and screwed the lot of us.
The worst part of these indecipherables was the time element. If an agent had a schedule for six o'clock, his message would have to be broken by then or his section head would insist that he repeated it. I didn't always manage to beat the clock, but only once gave up trying.
I had been working for two days on an indecipherable from Norway contributed by an agent called Einar Skinnarland. There was something very peculiar about Skinnarland's traffic. He gave some of his messages to a wireless operator to be transmitted in the normal way (SOE was blasé enough to regard wireless traffic as normal) -- but, for reasons which the Norwegian section refused to divulge, at any rate to me, most of his traffic was smuggled into Sweden by courier and re-routed to London by cable or diplomatic bag. He had already sent one indecipherable, and the usually imperturbable Wilson had stressed to me that he must know its contents within the hour. An hour in coding terms is only a paranoid minute. I needed to know what was so special about Skinnarland's traffic -- but Wilson rang off abruptly to take another call.
That first indecipherable of Skinnarland's had been a warming-up present from him to me and had proved no more troublesome than an undone shoelace. Wilson expected the new one to be cracked as easily. But Skinnarland had had the better of our two-day duel, and five minutes before his operator's schedule I just had to get away from the thousands of failed attempts which littered my desk. I strolled upstairs to the teleprinter room to listen to the healthy chatter of Dansey's main-line codes. Suddenly I knew what Skinnarland had done and saw that, if I took a short cut and drew together several columns of his message, I would get the word "sentries" in one line with the word "Vermok" immediately beneath it. Taking an even shorter cut to the code room by falling down the stairs, I contacted Station 53 on the direct line.
The operator was still on the air, about to be asked to repeat the message. I told the signalmaster to cancel the instruction and send the Morse equivalent of "Piss off fast."
Breaking that indecipherable to the applause of my public meant far more to me at the time than that factory in remotest Vermok which Skinnarland had described in minutest detail. The rest of SOE remained equally remote.
The most distinguished visitors to our mews stronghold were the night duty officers who collected the confidential waste and the ladies who pushed around the teatrolley twice a day like sisters of mercy. But one afternoon I was struggling with yet another indecipherable from Skinnarland, who was rapidly becoming my least favourite agent, when I heard an uncommonly authoritative, disconcertingly purposeful barrage of footsteps coming our way. A moment later an RAF officer strode into the room and commandeered it without a word being spoken. I had never seen anger of such quality and substance, power and purpose as this man projected. It should have been weighed by the pound and sold as an example.
I forgot about Skinnarland as he advanced on my startled superior, making no attempt to conceal his repugnance at a pink slip (an internal message to Station 53) which was clutched in his outstretched hand.
"Who's responsible for sending this?"
The flight lieutenant transferred his attention to me, and his first question set the tone of our encounter: "Who the devil are you?"
Every officer in SOE was allocated a symbol for use in correspondence; Dansey's was DYC, Owen's DYC/O. At last I had a chance to use mine. "DYC/M," I said, quoting it with relish.
"Tony had a sked at nine tonight. You've bloody cancelled it! Why?"
Tony was an agent stranded in France with the Gestapo searching for him. A Lysander was standing by to pick him up, but his message giving map references had been indecipherable. He was due to repeat it.
"I cancelled it," I said, "because an hour ago we broke it after three thousand, one hundred and fifty-four attempts."
Skinnarland's indecipherable whispered something to me in its coding sleep.
"How did you break it?"
A word was forming which could be "mountain".
"How did you break it?"
It was "mountain".
"By guess and by God," I said without looking up.
"Really, DYC/M? And which were you?"
"Barren mountain" -- I hoped it would make sense to Wilson.
"Flight Lieutenant, if you come back in a year's time I may have finished this bugger, and I'll be glad to answer all your questions."
"Very well, DYC/M. I'll look in again the Christmas after next, if you haven't won the war by then."
He closed the hangar door behind him. I could still feel him looking at me.
"Who was that sod?"
"Didn't you know? That's Yeo-Thomas. Our Tommy!... he's quite a character."
I didn't realize it at the time but "quite a character" was even more of an understatement than 84's tax returns.
Copyright © 1998 by Leo Marks. All rights reserved. Converted for the Web with the permission of Simon & Schuster.
Click to Amazon to purchase "Between Silk and Cyanide: A Codemaker's War, 1941-1945."