One
A Telegram Waylaid
The first message of the morning watch plopped out of the pneumatic tube into the wire basket with no more premonitory rattle than usual. The duty officer at British Naval Intelligence twisted open the cartridge and examined the German wireless intercept it contained without noting anything of unusual significance. When a glance showed him that the message was in non-naval code, he sent it in to the Political Section in the inner room and thought no more about it. The date was January 17, 1917, past the halfway mark of a war that had already ground through thirty months of reckless carnage and no gain.
On duty that morning in the inner room, the most secret in Whitehall, were two civilians diverted to cryptographic work masked under the guileless name of Room 40. One was the Reverend William Montgomery, a tall gray-haired scholar of forty-six, and the other Nigel de Grey, a young publisher of thirty-one borrowed from the firm of William Heinemann. Neither knew they were about to midwife a historic event. De Grey spread open the intercept, revealing rows of numerals arranged in four- and five- and a sprinkling of three-figure groups. Mute and passive on the paper, they gave forth no hint that a key to the war’s deadlock lay concealed in their irregular jumble. De Grey noticed only that the message was of unusual length; more than a thousand groups, he estimated.
The gray morning was cold as Britain’s fortunes, dingy as her hopes in this third winter of the war. The ghastly losses on the Somme—sixty thousand British casualties in a single mad day, over a million Allied and enemy losses in the five-month battle—had been for nothing. The Hindenburg Line was still unbreached. The whole war had been like that, regiments of lives spent like water, half a million at Verdun alone, without either side’s winning a strategic advantage, but only being riveted together like two fighting elks who have locked horns. Now the French were drained, the Russians dying, Rumania, a late entry on the Allied side, already ruined and overrun.
The enemy was no better off. Germans were living on a diet of potatoes, conscripting fifteen-year-olds for the army, gumming up the cracks that were beginning to appear in the authority of Kaiserdom with ever harsher measures. The German offer a few weeks before to negotiate a peace had been a mere pretense, designed to be rejected so that the General Staff could wring from the home front and faltering Austria yet more endurance and more sacrifice. Room 40 suspected it must have an ulterior purpose, for there was no evidence so far that the German leaders were any less obstinately fixed on total victory than the Allies.
England had fortitude left, but no money and, what was worse, no ideas. New commanders stumbled forward in the old rut, not questioning whether to assault the Western Front again, but merely where along its wall to bang their heads. No prospect of any end was visible.
Montgomery and de Grey examined the close-packed groups of numerals they were supposed to transform into verbal intelligence, expecting no more than another piece in the prolix correspondence they had been intercepting lately between Berlin and Washington about a negotiated peace. This was President Wilson’s cherished goal. Bent on stopping the war, he quested after a compromise peace between mental blinkers, blind to both combatants’ utter unwillingness to compromise at all. Berlin kept him talking in order to keep him neutral. The talk exasperated the Allies. It was not mediation they wanted from America but her great, fresh, untapped strength. Nothing else could break the war’s deadlock. Arms, money, ships, men—everything the exhausted Allies needed was waiting in America, but Wilson would not budge. He remained unmoved behind his eyeglasses, lecturing both sides how to behave. It seemed there was nothing that would bring in the Americans before Europe exhausted itself beyond recovery.
De Grey’s eye caught the top group of numerals in the message, 13042, and recognized it as a variant of 13040, title number of the German diplomatic code. He pointed it out to Montgomery, who unlocked the safe and took from it a book which he handled as he might have a bottle labeled poison! If there was no visible skull and crossbones on the book’s cover, there was more than one in its history, for the sea-bottom had been scraped and blood and life and honor spilled to assemble it. It was a reconstruction of the German code book for Code No. 13040. With it Montgomery took out another book that contained all that Room 40 had collected on the variants of the code. Through painstaking filing and collation of hundreds of intercepts, they had progressed toward a solution of the variants and so had built up a partially reconstructed key to use in cases like the present one.
The decoders tried first for the signature, which might give them a lead as to the nature of the message. A group in the 90000 range, 97556, appeared as the last group but two in the last row. High numbers such as this were usually reserved by the encoders for names or special words of infrequent use which were added as a supplement after the body of the code was made up. Working from earlier reconstructions in the code book, Montgomery and de Grey concentrated upon 97556. Obediently, as if tapped by a wand, it transformed itself into a name they knew well, “Zimmermann,” the German Foreign Secretary.
Going back to the beginning, they searched for the addressee, but instead of a name the first words to emerge were “Most secret,” and then they made out, “For Your Excellency’s personal information.” As the message was directed to Washington, the Excellency in question must be the German Ambassador there, Count von Bernstorff.
Routine so far, they were just about to decide, when an unexpected word appeared—“Mexico.” Wondering what the Germans could be saying about Mexico, they worked on with added interest, decoding the word “alliance” and farther on, to their astonishment, “Japan,” which was repeated in a phrase that came out as “us and Japan.” The decoders looked at each other with a wild surmise. Was it possible that Japan, one of the Allied powers, was changing sides? Urgently now they renewed the attack, their muttering dying away into concentrated silence as their scribbling speeded up. The code book pages flipped back and forth with an agitated rustle while sheets of paper filled up with words tested and discarded, with more words fitted together until, after two hours and in spite of many gaps in the sequence, an intelligible version had come clear.
It fell into two parts, for the intercept contained two separate telegrams. The first and longer one, addressed to Bernstorff, informed him of Germany’s intention to resume “unrestricted” submarine warfare on February 1, a decision expected and dreaded by the Allies for many months. “Unrestricted” meant that the U-boats were to be permitted to sink without warning all neutral as well as enemy merchant shipping found in the war zones. Bernstorff was instructed not to deliver the notice to the United States government until February 1, the very day the torpedoes would be let loose. Preparing for the belligerency that they believed would be America’s answer to the U-boat, the Germans had added another telegram. It consisted of 155 code groups and was headed, “Berlin to Washington. W 158. 16 January, 1917. Most Secret. For Your Excellency’s personal information and to be handed on to the Imperial Minister in Mexico by a safe route.”
The message for the Imperial German Minister in Mexico, Heinrich von Eckhardt, was headed “No. 1” and, in the incomplete version so far decoded, read:
We propose to begin on February 1 unrestricted submarine warfare. In doing this however we shall endeavor to keep America neutral . . . (?) if we should not (? succeed in doing so) we propose (? Mexico) an alliance upon the following basis: (joint) conduct of war, (joint) conclusion of peace . . . your Excellency should for the present inform the president secretly (? that we expect) war with the U.S.A. (possibly) . . . (Japan) and at the same time negotiate between us and Japan . . . please tell the president that . . . our submarines . . . will compel England to peace within a few months. Acknowledge receipt. Zimmermann.
The significance of the message the decoders could hardly let themselves believe. Zimmermann had given Room 40 the lever with which to move the United States. Mexico was both America’s chief foreign investment area and chief trouble spot, where twice in the last three years American troops had gone in shooting and where, at that moment, twelve thousand men under General Pershing were deeply engaged. The United States was also exceedingly jumpy about Japan. In the circumstances, Zimmermann’s spectacular proposal, picked out of the endless whispering in the air, must surely dynamite the Americans out of their neutrality.
In the telegram there was a blank passage of thirty groups from which the decoders had been unable to pry any meaning whatever. They could not guess that it contained the most explosive material of all. Only after weeks of patient, unrelenting effort were they able to reconstruct this portion of the code and discover that the missing passage contained Germany’s promise to assist Mexico “to regain by conquest her lost territory in Texas, Arizona, and New Mexico.”
Enough was at hand to require immediate action. This was a matter for the DNI, otherwise Admiral Hall, Director of Naval Intelligence. Montgomery hurried out of the room to fetch him. He returned, preceded through the door by a small ruddy man with authority in his step and an admiral’s gold stripes on his sleeve. The physical presence of Admiral Sir William Reginald Hall frequently nerved in men an impulse to do something heroic. For once de Grey, as he stood up and silently handed the scribbled sheets to the admiral, felt equal to the moment.
“Zimmermann, eh?” said Admiral Hall while his eyes darted over the pages. As he read, the intermittent eyelid twitch for which he was nicknamed “Blinker Hall” quickened, the compact little figure seemed, if possible, to stiffen, the brilliant blue eyes to blaze almost literally, and the tufts of white hair to bristle around the bald pink head until he looked like a demonic Mr. Punch in uniform.
Hall knew instantly that he held in his hands notice of what was at once a deadly peril and a possible miracle. Only the miracle of America’s entrance into the war could outweigh the peril of the unrestricted submarine, which, once let loose, might well accomplish what the Germans hoped—cut the Allies off from their source of supplies before the Americans had time to mobilize, train, and transport an army to help them. That was the stake the Germans were playing for.
Hall had known for months it would have to come to this, for the submarine was never designed for the gentlemanly role President Wilson seemed to think proper. To demand that it rise to the surface to warn before sinking, making itself a sitting duck in case its prey should shoot first, made nonsense of its function. He knew the Germans had accepted Wilsonian restrictions not because of the moral force of the President’s notes tapped out on his private typewriter, but only because they had not enough U-boats on hand to force the issue. Since then, he knew too, Kiel’s machine shops had been burning day and night, forging U-boats as fast as they could toward the goal of the two hundred Germany needed before letting loose a massive naval Verdun she hoped would bring Britain to her knees. Today’s telegram was the signal that the two hundred must be nearly ready.
“Two weeks,” Hall said aloud. In two weeks it would be February 1, the date staring up at him from Zimmermann’s dispatch, when Britain’s war effort, already hanging by its thumbs from Persia to the Channel on a lifeline of sea-borne supplies, would meet its greatest test. “Compel England to peace within a few months,” Zimmermann’s closing words had boasted. Hall knew it was no idle boast.
His mind racing ahead, Hall tried to think like a German. They had taken a desperate gamble, knowing unrestricted warfare might flush the reluctant dragon in the White House out of his cave. Obviously they must have made up their minds that the U-boats could sink ships faster than the Americans could mobilize, and it was even possible the Americans might not mobilize at all, in which case the gamble would pay off. But here in Hall’s hands was a persuader, thoughtfully provided by Herr Zimmermann himself, that should help to make up the American mind.
Hall understood well enough why Zimmermann had sent the telegram. In case America should answer the U-boat threat by declaring war on Germany, he wanted to arrange enough trouble for her to keep her busy on her own side of the Atlantic. It was the shrewd, the clever thing to do—and he had done it, aiming straight for Mexico and Japan, the two whose long hostility to the United States gave most promise of readiness to jump to the attack. How right and proper! How correct!
Ah, yes, the Germans were clever, thought Hall with an inner smile, but just that fatal inch short of being clever enough to suspect that their enemy might be clever too. Sublimely confident that their code was as nearly perfect as human minds could devise—was it not scientific? was it not German?—they had used it unchanged since the first day of the war, assuming its inviolability. In war, never assume anything, Hall reflected, in the happy knowledge that every German wireless message was being grasped out of the ether and read in Room 40.
As Hall headed back to his own room he was reminded of a duty. He would have to inform the Foreign Office, and the thought dimmed his satisfaction. He hated sharing news of Room 40’s coups with anybody, lest even a whisper get abroad to warn the Germans. Now he was seized by the agonizing problem that always haunts the cryptographer: how to make use of his information without revealing that he knows the code.
Faced with such a problem, armies have been known to avoid warning their own men of enemy movements when such a warning would show knowledge that could have been gained only by possession of the enemy code. How, Hall asked himself, could the Zimmermann telegram be revealed to the Americans without revealing how it had been obtained? They would never believe it on the mere say-so of the Foreign Office. They would ask inconvenient questions. If the Germans discovered Room 40 had solved their code they would never use it again, and a whole delicate listening apparatus, carefully constructed, wire by wire, over two and a half years, would go dead. A new code might take years to break, as it had taken years, the genius of a few men, the lives of others, the long, patient months of plugging, to break this one. Hall could not risk disclosure.
Copyright © 1985 by Barbara W. Tuchman. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
