The Zimmermann Telegram Read online

  “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.

  Room 40 had sprung from an act done in the first hours of the war. England had declared war at midnight on August 4, and before the sun rose the next morning a ship moved slowly through the mist over the North Sea until she reached a point some miles off Emden, where the Dutch coast joins the German. In the half-darkness she began to fish in a manner that was strangely clumsy yet purposeful. Heavy grappling irons were plunged into the water, dragged along the bottom, and hauled up, bringing with them an eel-shaped catch, dripping mud and slime, that clanged against the ship’s side with a metallic sound. Several times the maneuver was repeated, and each time the eel-like shapes were cut and cast back into the sea.

  They were the German transatlantic cables. Five of them ran through the English Channel, one to Brest in France, one to Vigo in Spain, one to Tenerife in North Africa, and two to New York via the Azores. The English cable ship Telconia cut them all. She had no need to move on to the Mediterranean, for the cables there were English-owned, but a few days later she returned to the North Sea and, to exclude any possibility of repair, wound up the severed cable ends on her drums and carried them back home. It was England’s first offensive action of the war and was to have results more lethal than were dreamed of when the Committee of Imperial Defense planned the action back in 1912. For two years an order authorizing the cable-cutting had lain dormant in Admiralty files, until the morning of August 4, 1914, when the German Army, glistening in spiked helmets and polished boots, marched into Belgium. Someone, on that day that ended a world, remembered the order, dug it out of the files, and dispatched it to the General Post Office. By midnight, when England’s ultimatum on Belgian neutrality officially expired, the Telconia was already on her way.

  After the Telconia’s work was done, only one cable remained open to Germany; this was one that ran between West Africa and Brazil and was largely American-owned. For a short time Germany was able to wireless messages to Africa and have them sent on from there in safety to South America and thence to the United States. When the British government, unwilling to risk American displeasure, refused to touch this cable, Hall’s predecessor, Admiral H. F. Oliver, took his problem directly to Eastern Telegraph, the company that owned the Mediterranean cables. The company quietly pulled cousinly wires and was delighted to inform Admiral Oliver a few weeks later that the matter was satisfactorily arranged: they had thirty miles of the Liberial-Brazil cable in their tanks.

  From that moment on, for the duration of the war, Germany was sealed off from direct cable communication with the overseas world, and the burden of communication fell on Nauen, the powerful German wireless station a few miles outside Berlin. Nothing can stop an enemy from picking wireless messages out of the free air—and nothing did. In England, Room 40 was born.

  When intercepts in code began pouring over the desk of the Director of Naval Intelligence, at that time Admiral Oliver, the painful discovery was made that no one had been trained to deal with them. For two years the rumble of approaching war had been heard, but the Senior Service, never doubting its mastery of the seas, had prepared for it in the spirit that often governs play rehearsals: “It will be all right on the night.” Harassed and sleepless in the frantic first hours of the war, Admiral Oliver thought of a soft-spoken Scot named Alfred Ewing, a former professor of Mechanical Engineering who was Director of Naval Education. Ewing, he remembered, had made a hobby of constructing ciphers. Oliver sent for him and handed him a bundle of intercepts. Under shaggy eyebrows the blue eyes of the little Scot brightened with interest as he agreed to see what he could make of them. Relieved, Admiral Oliver gave orders that henceforth all intercepts were to be delivered to Mr. Ewing, and turned his attention to other matters.

  Ewing found himself surrounded by ciphers and codes and was soon blissfully absorbed in an occupation he had followed ever since as a small boy he had won a newspaper prize for solving an acrostic puzzle. As the intercepts piled up around him, Ewing was obliged to call for help from one or two discreet friends who were amateur cryptographers like himself or had a knowledge of German. This was how Montgomery was recruited from the Presbyterian ministry, for, besides being an authority on St. Augustine, he was a gifted translator of theological works from the German. No work, it was said, had ever been so idiomatically and yet so faithfully rendered as Montgomery’s translation of Schweitzer’s Quest of the Historical Jesus, published in 1914. He and Ewing’s other recruits studied code books at the British Museum, collected commercial codes from Lloyds and the G.P.O., plunged themselves into the intricacies of Playfair and Vigenère squares, alphabet frequencies, single and double substitutions, grilles, and word wheels.

  All the while German submarines and other fleet units were constantly chattering with one another and with Berlin, while the wireless station at Nauen, conducting policy over the air, issued streams of instructions around the world. To catch this verbal outpouring, four new listening stations were set up along the English coast with direct wires to the Admiralty basement; amateur wi
reless operators who were picking up unintelligible signals on their sets increased the flow of intercepts. Soon they were coming in at the rate of two hundred a day, overwhelming the staff Ewing had increased to five. He recruited more assistants—university dons, barristers, linguists, accountants with a flair for mathematical pattern, all men who went into battle against the ciphers with a zest for the intellectual challenge.

  Cipher differs from code in that it is constructed upon a systematic method in which one letter or group of letters (or number or group of numbers) represents another letter or group according to some prearranged pattern. Code, on the other hand, is based on arbitrary substitution in which the substitutions are listed in a code book made up by the encoder. Sometimes a word is substituted for another word or idea—as, for example, in its simplest form, “Overlord” in 1944 was the code word for “Invasion of Normandy.” Or, as in the case of the Zimmermann telegram, a code can be based on the substitution of an arbitrary group of numerals for a word as, for example, in the telegram 67893 represented “Mexico.” Generally, although not always, when the Germans used code they wrapped it inside an extra covering of cipher; that is, they enciphered the code. The key to the encipherment they changed frequently—as time went on, every twenty-four hours. But, being orderly Germans, they changed it according to an orderly system which, once solved by the cryptanalysts of Room 40, could be solved again each time by progressing according to a constant pattern. For some reason still obscure, the Zimmermann telegram, when it was sent, was not put in enciphered code.

  From the beginning, the Germans, heaping the air with their messages, ignored the possibility of their codes and ciphers being solved because they considered the enemy unequal to such intellectual exercise. The very number they sent out, often in duplicate and triplicate over two or three different routes, greatly facilitated Ewing’s task by giving him several versions of the same message, and it was not long before his band of amateurs, with the aid of technical methods and machines they had improvised, were reading Berlin’s messages more quickly and correctly than the German recipients. One wizard, working upon a series of numerals extracted out of the air over Macedonia, was able to transform the cipher into words which he himself could not read but which turned out to be the instructions of the Bulgar General Staff in Bulgarian.

  To the ordinary mind it seems impossible that a code based on substitutions arbitrarily chosen by the encoder can be solved—or, as the cryptographers say, reconstructed—by a person not in possession of the code book. Yet in time, with a sufficient number of messages to compare, with ingenuity, endless patience, and sparks of inspired guessing, it can be done. One has only to imagine the infinite difficulty of the process to realize the worth of the short-cut provided when a copy of the enemy code book is captured.

  On October 13, 1914, came one such extraordinary windfall. In response to a call from the Russian Embassy, Admiral Oliver and Ewing hurried over and were conducted to a private room where they were introduced to a staff officer of the Russian Admiralty who handed them a small, rather heavy package. Opening it, Oliver and Ewing could hardly believe their luck; under their eyes was the German naval code book, lined in lead for quick jettison overboard in case of need.

  “Magdeburg” was the one-word explanation offered by the Russian officer. Oliver remembered a German light cruiser of that name that had been lost in the Baltic in August. She had been escorting mine layers in the Gulf of Finland, the Russian officer told them, when she ran aground in a fog off the island of Odensholm. Through a break in the fog her captain had seen two Russian cruisers bearing down upon him. Quickly he ordered his signalman to fetch the code book, row out to deep water, and throw it overboard. Just as the dinghy was being lowered, a shot from the Russian guns tore into it and, in his moment of death, the signalman’s arms clutched the code book to his body. The Russian cruisers, closing in, destroyed the Magdeburg and proceeded methodically to the rescue of the German sailors floundering in the water. Someone spotted a floating body, which was hauled aboard with the living; it was the dead signalman, still clasping the code book in his arms.

  The Russian Admiralty at St. Petersburg, exhibiting rare good sense, had decided the code could best be used by the British Admiralty and, with even rarer generosity to an ally, had sent it by fast cruiser to London. Oliver and Ewing found in the Magdeburg’s salt-soaked relic not only the word columns on which the naval code was based but also a key to the cipher system according to which the code was varied from time to time. This gave them a clue to German cryptography which was the root and fundament of all that followed.

  In November, upon the promotion of Admiral Oliver to Chief of Staff, a crackling breeze blew through Admiralty corridors with the advent of Captain William Reginald Hall, fresh from the bridge of a battle-cruiser, as the new DNI. The new Director was known as a precedent-breaker. In 1913, sniffing war in the air, Hall had put his ship, for greater alertness, on eight-hour watches instead of the traditional twelve, and ordered gunnery practice for the crew instead of leaving the gun mounts with their paint unmarred, as was customary. His innovations outraged the Mandarins, as the naval Colonel Blimps were called, but Hall, operating on the quaint theory that the Navy might be needed for battle and that whatever increased the ship’s efficiency was a criterion for change, had continued trampling on the toes of orthodoxy.

  His first act as DNI was made on the same principle. On finding the Intelligence staff overflowing its original space, he moved out of the main Admiralty building into a quiet backwater next door known as the Old Building. Here, set apart from bustle and visitors, was an isolated suite of rooms giving off Number 40. Although the staff later moved again to larger quarters, the name Room 40, O.B., so noncommittal that it stirred no curiosity, stuck to the operation throughout the war, as it has in the halls of cryptographic fame ever since. By the time the Zimmermann telegram was intercepted, Room 40 employed eight hundred wireless operators and seventy or eighty cryptographers and clerks.

  Hall knew nothing about cryptography, but he instantly saw the absorbing opportunities for thwarting the Germans that were being opened by Ewing’s cracksmen. The war had just become world-wide, spilling over the Middle East when the Turkish Empire joined the Central Powers a few days before Hall arrived in Whitehall. Hall soon jumped the original horizon of Naval Intelligence and arrogated to himself the task of counter-plotting against German intrigues anywhere in the world. He began at once to penetrate into every cranny of espionage, until no man’s pie was free of his ambitious finger. Scotland Yard, tracking German spies, found Hall helping them; the censorship bumped up against him; so did the Blockade Bureau, the War Department, the Secret Service. Wherever intelligence was being gathered and turned against the enemy, there was Hall; wherever was a spot from which trouble might come, there he placed an agent or established contact with an Allied sympathizer. Like God in the British national anthem, Hall was ready to confound the politics and frustrate the knavish tricks of Britain’s enemies. He was ruthless, sometimes cruel, always resourceful. His piercing eye, his unrelenting drive, his magnetism could get anything he wanted out of anybody. Wherever Germans were plotting, Hall was listening and, like dogs who can hear high-pitched sounds that never reach the human ear, Hall could hear intrigues hatching anywhere in the war. The more Room 40 decoded, the more came into his net: Indian revolutionaries and Irish rebellions, Sir Roger Casement and Mata Hari, German-fomented strikes and German sabotage. But all this activity was carefully masked by a bland pretense of ordinariness that implied that Naval Intelligence was no more than it was supposed to be, a lot of chaps busily tracking German fleet movements, locating U-boats by intercepted wireless signals, and charting mine fields. As this, in fact, was just what Room 40’s outer group was doing, it provided the perfect cover for the activities of the inner group.

  Leaving cryptography in Ewing’s charge, Hall himself directed the efforts to acquire the German code books. Sooner or later any whisper or hint o
f a code picked up by Army, Navy, diplomatic, or other agents found its way to him. In December 1914 an iron-bound sea chest was delivered to Room 40 and identified as having come from one of a group of four German destroyers that had been sighted, chased, and sunk by the English on October 13. For two months the chest had lain on the bottom until by chance it was hauled up in the net of an English fish-ing trawler. Among the charts and confidential papers it contained, Room 40 found a code book whose use remained obscure for some time. After months of bafflement, comparison with certain intercepts proved it to be the code used by Berlin for communicating with German naval attachés abroad.

  In the meantime, two strange dramas, a tragedy and a frontier adventure, were being enacted simultaneously, one in Brussels and one in Persia, each to have its denouement in Room 40.

  When the Germans occupied Brussels on August 20, 1914, they found there a powerful wireless sending station that had gone out of order, and a twenty-year-old university student of wireless engineering who, it was said, could fix it. The young man, whose name was Alexander Szek, was of dual nationality by virtue of British birth and Austro-Hungarian parentage. He had grown up in England with his parents, but two years before the war he had moved with his father to Brussels, where he remained to study while the father went back to Vienna to live. Someone of Szek’s family, either his mother or a sister, had remained in England. (The facts in this part of the Szek case are fuzzy, so we do not know exactly who it was.) The Germans naturally chose to consider young Szek an Austrian citizen and, as the alternative to sending him to Vienna for military service, commandeered his services for the Brussels station. Working there, he had access to the code.