Seizing the Enigma (6 page)

Galibin lowered the black, white, and red German naval war flag and raised the white czarist flag with its diagonal light blue cross. Then, revolver in hand, he searched the wreck of the
Magdeburg.
He found a locker in Habenicht’s cabin and broke it open. Hidden deep within it was a German codebook, forgotten by all in the excitement of the catastrophe. Galibin removed it and, together with a packet of Bender’s private letters and other documents, had it transferred to the
Lejtenant Burakov
, The Allies had come into possession of the key secret of the Imperial German Navy, the one that could give them access to many others.

Later, Russian divers supplemented Galibin’s find. Using strong electric lights to inspect the stony seabed up to 30 feet from the stranded vessel, they found in the clear waters the codebook that Szillat had thrown overboard and the one that Neuhaus had lost in the water.

Recognizing the value of the codebooks and cipher keys to the British, the major naval power, the Russians loyally notified their ally of their find and said that they would give the British the documents
if they would send a small warship “as most secure means” of getting them and the officers accompanying them to Britain. The Russians courteously set aside for the British the undamaged code, the one found in Habenicht’s locker, which bore the serial number 151. They kept the waterlogged codes for themselves.

The task of taking codebook No. 151 to England was assigned to three naval officers, Captain Mikhail A. Bedrov, Commander Mikhail I. Smirnov, and Count Constantine Benckendorff. A cosmopolitan, mustachioed combat veteran of the Russo-Japanese War, Benckendorff was the son of the ambassador to Great Britain. He had served a year as a cipher clerk in the London Embassy. One Sunday morning in September he was on watch on the battleship
Poltava
in Tallinn roadstead, pacing the quarterdeck and listening to the sailors’ choir chanting the Russian Orthodox mass, when a yeoman handed him an order to report immediately to the flag captain. On the flagship he was “amazed and delighted” to be told he would be going to London.

He was given the precious codebook in St. Petersburg. It was in a satchel with a large piece of lead sewn in to make it sink in case he had to throw it overboard and with a strap to carry it over his shoulder. This bag he took with him to Archangel, where he boarded a Russian volunteer fleet steamer. The vessel was to meet H.M.S.
Theseus
at Alexandrovsk (now Polyarnyy), a port near Murmansk, where the aging cruiser had arrived early in September. Owing to delays and misunderstandings, the
Theseus
and the steamer did not sail until October 1. After an uneventful crossing over the top of Norway, punctuated only by a few vague U-boat warnings, they arrived on October 10 in Scapa Flow, the great circular basin north of Scotland that served as one of the Royal Navy’s chief bases; the Russian steamer went on alone, reaching the English port of Hull a couple of days later. After a slow night train ride, Benckendorff reached the Russian embassy at dawn. He greeted his parents, then routed out the naval attaché, and the two went, early on the morning of October 13, to the Admiralty. There, in one of the most significant moments in the long
history of secret intelligence, they handed Winston Churchill, first lord of the Admiralty, a gift more precious than a dozen Fabergé eggs: the big, fat, blue-bound
Signalbuch der Kaiserlichen Marine.

The
Signalbuch
went to the Admiralty’s fledgling codebreaking agency. This had come into being, quite by chance, on the day Britain entered the war. Though individuals in the British army had solved cryptograms in the Boer War and on India’s Northwest Frontier, the navy had never engaged in cryptanalysis and had made no preparations for it. But when hostilities formally commenced on August 4, 1914, radio stations of the Royal Navy, the post office, and the Marconi company began to pick up coded messages, apparently of German origin. These they forwarded to the Admiralty’s Intelligence Division. Its director, Rear Admiral H. F. Oliver, recognized their potential and knew at once who might realize it: his good friend, the director of naval education, Sir Alfred Ewing. A short, thickset Scot, given to wearing mauve shirts with white wing collars and a dark blue bow tie with white polka dots, Ewing was a distinguished engineer. He had dealt with cables in Uruguay and had, a year or so before, described a cipher mechanism to Oliver. Oliver regarded him as of “very great brain power, in fact a man who stood out among clever men.” Everyone thought naval education would not be much needed during the few months until victory was won. Oliver told Ewing he had no one to deal with the intercepts; would Ewing see if he could make anything of them? Grasping “at even the most unpromising chance of being useful,” Ewing accepted at once.

To assist him, he called on some people whose abilities would be useful and who were discreet and available: faculty members, particularly instructors in German, at the Royal Naval Colleges at Dartmouth and Osborne, which were on vacation in August. One of the first volunteers was Alastair Denniston, thirty-three, a German master at Osborne. A short, quiet Scot, he had studied at Paris and Bonn and had helped win a bronze for Great Britain in field hockey
as a member of the Scottish team in the 1908 Olympics in London. Like the others, Denniston was, in his own words, “singularly ignorant of cryptography.”

He and his colleagues worked in Ewing’s cramped office. They did little more than sort and file intercepts, learn to distinguish German naval messages from military ones, and discover that call signs such as POZ and KAY, the “names” of radio stations, were not the same as the coded texts of messages. But they made not a dent on the German naval messages.

A month later, the
Signalbuch
from the
Magdeburg arrived in Ewing’s office.
But what seemed to be the answer to a cryptanalyst’s prayer did not at first turn many of the coded messages into plain German. The book consisted essentially of hundreds of pages of columns of five-digit and three-letter groups standing opposite German words:

63940 OAT	Ohnmacht -ig
41 OAU	Ohr, Ohren-
42 OAÜ	Okkupation, Okkupations, -ieren
43 OAV	Ökonomie -isch
44 OAW	Oktant
45 OAX	Oktober

This meant that
Oktober
would be encoded as OAX or 63945, and OAÜ (the Germans usually used the letters, not the numbers), would mean
Okkupation
or its derivatives. But attempts to reduce the intercepts to German by this straightforward method produced gibberish in most cases; the only messages that were solved were weather reports and messages to auxiliary vessels. To resolve the mystery, Ewing brought in the head of the Intelligence Division’s German Section, Fleet Paymaster Charles J. E. Rotter, who had spent many leaves in Germany. He was installed in Ewing’s secretary’s office.

A break came when the
Handelsschiffsverkehrsbuch
, or
HVB
, another maritime code, seized from a merchantman off Melbourne, Australia, arrived at Ewing’s office, along with a method for disguising
the code’s four-letter codewords. The letters of the codewords were replaced with other letters given in a list, or key. For example, the codeword for
Fregattenkapitän
(commander) was RABL; the key specified that the substitute for R was T, for A, L, and so forth, so that RABL would actually be transmitted as TLIN. This procedure is called superencipherment.

Rotter seems to have reasoned that the Germans were using the same system to encipher the codewords of the
Signalbuch
, so that OAO might become, for example, JVJ. Working with a succession of messages whose serial numbers the Germans had enciphered—“Their folly was greater than our stupidity,” Alastair Denniston commented—Rotter by early November had discovered the key to the superencipherment, thus exposing the main messages of the High Seas Fleet.

This breakthrough suddenly gave the handful of cryptanalysts plenty to do. More cryptanalysts were taken on, and a new, larger workplace was found, Room 40 of the Old Building of the Admiralty. “Room 40” became the unofficial name for the codebreaking agency.

Early in December this thriving and fortunate agency got another lucky break. The third major codebook of the Imperial German Navy arrived in sodden condition in Ewing’s office. The captain of the torpedo boat S-119 had thrown it and other papers overboard in a lead -lined chest when he encountered a British squadron off a Dutch island; a month and a half later a British fishing boat hauled it up in its trawl. Soon the new codebook, the
Verkehrsbuch
, a five-numeral code
(Kaiser =
46786) used at sea by flag officers, was drying before Ewing’s fire.

The new book too was used with a superencipherment, which was discovered the day the book arrived. Some days earlier the British had intercepted two almost identical German naval messages. One was encoded entirely in the
Magdeburg codebook
and so could be read by Room 40. A small part of the second was encoded in the newly found code. “It is never wise to mix your ciphers,” Ewing remarked. “Like mixing your drinks, it may lead to self-betrayal”
This did. The
Signalbuch
gave the meaning of the coded portion of the
Verkehrsbuch
message; these German words could be looked up in the
Verkehrsbuch
to find the basic codenumbers, and comparison of those with the superenciphered codenumbers of the message revealed the formula for conversion.

Thus, before the war was four months old, Britain had gained, mainly through means other than codebreaking, the ability to read the most secret intentions of its chief enemy’s navy.

Nor did Britain’s cryptologic gifts from the sea end there. Later in the war the Germans changed their codes, but divers recovered the new ones and their superencipherments from U-boats sunk in the shallow waters around Britain. One of the most successful of these divers was Shipwright E. C. Miller, a pale, wiry young diving instructor. His most remarkable characteristic was a sangfroid in facing horrors that would have frightened off many other men. Once he investigated a German submarine sunk off the Yorkshire coast. She was lying on her side, and Miller found no point of entry. He rigged charges and blew off the top of the conning tower. As the water cleared, he saw the head of a dead German seaman rise above the ragged rim of the conning tower as if peering out. That didn’t stop Miller. In his bulky suit and spherical armored helmet, he clambered in. At once the imprisoned corpses crowded around him. He calmly tied them up with lanyards and pursued his exploration of the U-boat, stumbling through the narrow black passageway of the underwater tomb until, in a compartment aft of the officers’ quarters, he found a strongbox. This contained one of the new codes and some of its superencipherment keys.

As the war progressed and the value of codebreaking became increasingly obvious, the staff of Room 40 swelled. Ewing recruited many members from Cambridge University, where he himself had been a professor of mechanical engineering, and from that university’s King’s College, of which he had been a fellow. Curiously, more of his recruits were classicists and linguists than mathematicians and
scientists. One who proved most successful was a scholar of Greek named Alfred Dillwyn Knox, called Dillwyn.

He was the second of four sons of the Anglican bishop of Manchester. At Eton he became close friends with the future economist John Maynard Keynes. At King’s he refused the homosexual advances of Lytton Strachey, the future author of
Eminent Victorians
, who had fallen in love with him.

“Did I tell you,” Strachey wrote of Knox, “that he has a wonderful veil of ugliness that he is able to lower at any minute over his face? His method is, you see, to lure you on with his beauty, until at last, just as you step forward to seize a kiss, or whatever else you may want to seize, he lets down a veil, and you simply fall back disgusted. Isn’t it a horrid trick?” Witty, clever, always ready with a new limerick, Knox played first-rate bridge with unorthodox moves that more often than not succeeded. But Keynes, who followed him to King’s, said, “He has got one of the most confused brains I have ever come across.… He is quite abnormally untidy in his work and always forgets to write down the most necessary steps.”

Knox, tall, thin, light of build, with full lips and a receding forehead, was elected a fellow of King’s in 1909, and for a short time he tutored Harold Macmillan, the future prime minister. He worked with his own tutor, a classics scholar, in preparing an edition of the minor Greek dramatist Herodas, whose sketches had been discovered at Oxyrynchus in Egypt in 1889 on a roll of papyrus. The copyist of this manuscript, Knox wrote, was “constantly puzzled by the form of the letters which he was copying,” was “prone to all the common errors of copyists,” and made “stupid alterations.” Knox and his tutor had to determine the correct meanings. The intense analysis and detailed reconstructions required by this kind of study are also needed in cryptanalysis, and when Knox was recruited for Room 40 early in 1915 at age thirty-one, he found codebreaking congenial.

He was followed to Room 40 by a younger friend from King’s, Frank Birch. Birch was seen as “a many-sided human being—a rather
dull historian, an acceptable drinking companion, a mysterious private personality, a brilliant talker and a born actor. In his impersonations, as in those of all great comedians, there was a frightening element.” One of his best was of a classics tutor, who had only one eye and one hand; in Birch’s pantomime, he took himself apart so thoroughly in his room each night that nothing was left of him at all. Birch, an Etonian and a keen yachtsman, had served at sea during the first part of the war. He and Knox shared a house at 14 Edith Grove in the Chelsea section of London, where Birch gave weekly musical parties; Knox chose those occasions to work all night at Room 40. Birch excelled less in codebreaking than in collating and explaining the results.