Seizing the Enigma (17 page)

By June 1937, the nucleus of the unit had been formed. Its first task was to track Italian submarines, and one of its early experiences led to a fundamental rule in handling communications intelligence.
G.C.&C.S. had sent the new body the gist of the solution of a message to two Italian submarines that Mussolini had placed at Franco’s disposition. The message said that any merchant vessel attempting to break the blockade was to be sunk outside of Spanish waters. This appeared unbelievable in the political situation, and the Foreign Office questioned it. An investigation showed that the G.C.&C.S. evaluator had placed his own interpretation on a not too clear text. From that time forward, G.C.&C.S. provided only the originals of solutions to the Admiralty.

In February 1939, two months after Germany announced that she would build as much tonnage in submarines as the British had, the nucleus evolved into the Operational Intelligence Centre (O.I.C.)—Section 8 of the Naval Intelligence Division. To head it, the director of naval intelligence named a retired contemporary, a one-time watch-keeper in Room 40, a man widely regarded as impossible to rattle, Rear Admiral John W. (Jock) Clayton. The O.I.C. had four sections: Italy and Japan, submarines, direction-finding, and surface ships and outside liaison, headed by Denning. Liaison with G.C.&C.S. was ensured by the presence in O.I.C. of a small party from Naval Section under Commander M. G. Saunders. The intercept and direction-finding stations were administered and controlled not by O.I.C. but by a combined signals division–intelligence division group, DSD/NID 9, under Commander Humphrey Sandwith. He and Denning pressed successfully to increase the number of intercept stations. Denning, seeing which way the wind was blowing, had a map drawn with Berlin at the center to give him the German point of view. Similarly, G.C.&C.S.’s Naval Section, which in 1937 had begun attacking German naval traffic for the first time since 1928, started a German subsection in May 1938 on Quex Sinclair’s recommendation. It consisted of an officer and a clerk, but no cryptanalysts for itself alone.

As the O.I.C. was coming into being, Sinclair, driven by a realization of the value of cryptanalytic information, the need for quiet in the work, the requirement for secrecy, and the likelihood of expansion
in case of war, had a landed estate called Bletchley Park in the railroad junction town of Bletchley, some fifty miles northwest of London, purchased for G.C.&C.S. The estate consisted of a manor house greatly expanded in Victorian style in the 1870s by stockbroker Herbert S. Leon and the surrounding acres of landscaped grounds.

Since the house could not accommodate the hundred-odd employees, G.C.&C.S. built “huts”—long, narrow, peak-roofed, one-story wooden temporaries that huddled near the big house, which was headquarters. In July 1939, a few months after Britain had guaranteed to aid Poland in case of German aggression, a few weeks after Hitler and Mussolini had formalized the Axis, a few days after the Soviet Union had rejected a British-French proposal to block further Nazi aggression, Sinclair ordered G.C.&C.S. to move to Bletchley Park, later usually referred to as B.P.

Dillwyn Knox went to an office in former servants’ quarters called the Cottage, a small, square, brick building. There he pursued his work on Enigma with the cipher machine given him by the Poles. But though they had shown that it was possible to climb this cryptologic Everest, many difficulties remained. In particular, the naval Enigma resisted solution. Its keying system and the navy’s more careful use of it offered no handholds for the cryptanalysts.

A few weeks later, as German-Polish tensions rose, the German battlewagon
Schleswig-Holstein
visited Danzig. She was there purportedly for a twenty-fifth anniversary memorial service for the dead of the
Magdeburg
, who were buried in a Danzig cemetery. Early in the morning of September 1, 1939, she trained her 11-inch guns upon a Polish military depot 400 yards away. At 4:48 a.m., without warning, they fired the first shots of World War II. The depot’s wooden buildings burst into flames. Moments later, hundreds of miles away, Hitler’s armies crossed Poland’s borders. Britain’s guarantee went into effect. Two days later, the island kingdom, whose survival rested upon its ability to rule the sea, was at war—unable to read the main enemy’s main naval cipher.

F
IVE DAYS AFTER
H
ITLER’S ARMIES INVADED
P
OLAND, THEY
surged to within forty miles of Warsaw. The Poles did not need their Daniels—their cryptanalysts—to read the handwriting on this wall. The army high command prepared to evacuate. The codebreakers burned papers and packed Enigma replicas, bombes, perforated sheets, and Polish cipher machines in heavy crates. On the night of September 5 they quit their offices for the Vilna railroad station. The evacuation train, leaving the next evening, took three days to cover the 125 miles to Brzesc (Brest), to the east of Warsaw. There Rejewski, Różycki, and Zygalski continued their journey by car. The codebreaking equipment was destroyed. The trio drove south, first in a mobile direction-finding vehicle with Major Ciȩżki and his family, later in a tiny car, with Rejewski bumping uncomfortably atop some batteries. After six days of detours, rain, and frantic searches for gasoline, the group, which included Colonel Langer, arrived at the tiny village of Kuty at the tip of the tongue of Poland that then protruded into neutral Romania. The village, whose normal population was 400, was packed with a confused mass of soldiers, diplomats, bureaucrats, automobiles, and horse-drawn carts, all striving to squeeze onto the two-lane bridge over the Cheremosh River, which marked the border. The codebreakers crossed during the night of September 17.

The Romanian authorities confined the military personnel but left the civilians on their own, so the three young cryptanalysts
caught a train to Bucharest. At the French embassy, they received visas promptly when they mentioned Bertrand, who had begun to search for them the day they entered Romania. Soon they were taking a succession of trains through Yugoslavia and Italy to France. They and a dozen other members of the Biuro Szyfrów arrived in Paris on October 1, some by special airplane, some by the Orient Express.

Five days later, the last of Poland’s forces surrendered to Germany. The defeat demonstrated an elemental point about intelligence: unlike guns or morale, it is a secondary factor in war. All the Polish codebreaking, all the heartrending efforts and the heroic successes, had helped the Polish military not at all. Intelligence can work only through strength.

But France was strong, or was regarded as such, and on October 20 the fifteen Polish cryptanalysts resumed their war against Germany, working under Bertrand. He now headed the so-called
Section d’Examen
(Examination Section), which performed radio intercept, traffic analysis, and cryptanalysis, of the General Staff’s Fifth Bureau, the mobilized form of the peacetime
Service de Renseignements.
As offices and billet for his section, Bertrand had requisitioned the Château de Vignolles, a large, three-story villa and associated outbuildings near the town of Gretz-Armainvilliers, some 25 miles northeast of Paris. The villa and its unit was called P.C. (
“Poste de Commandement”
) Bruno. Attached to it as what Bertrand called his Z Team were the Poles, who enrolled in the Polish army in France, and, as his D Team, seven émigré Spanish Republican cryptanalysts, whom Bertrand had enlisted in the Foreign Legion. Several dozen French cryptanalysts and support personnel brought the section’s total to seventy. Also present was Captain Kenneth Macfarlane, a British liaison officer, promptly nicknamed Pinky because of his rosy complexion; he had a direct teletypewriter line to Britain for exchanging results with Bletchley Park. The whole section ate meals together, and their differing tastes and temperaments led to sulks and arguments. Often, however, the problems were liquidated, so to speak, at the bar.

Rejewski and the others took up where they had left off. For weeks, the Enigma modifications of December 15, 1938, continued to defeat them. But toward the end of December 1939, assisted by a set of 1,560 Zygalski sheets that G.C.&C.S. had punched, P.C. Bruno recovered a German army key for October 28. A few weeks later, its solution of a Luftwaffe key for January 6, 1940, showed that the Wehrmacht had introduced no new procedures that would baffle the Allied cryptanalysts.

By that time Britain had achieved two remarkable breakthroughs that gave it the lead in Enigma cryptanalysis. These resulted from a shift in G.C.&C.S.’s thinking.

Toward the end of the 1930s, Alastair Denniston, the head of G.C.&C.S., had come to realize what the Poles had understood a decade earlier: that the shift to cipher machines required using mathematicians as cryptanalysts. So in the late summer of 1938, as British Prime Minister Neville Chamberlain flew repeatedly to Germany to appease Hitler, the British codebreaking agency held a series of courses in cryptology primarily for mathematicians. The move brought into the closed world of British communications intelligence the fresh thinking of a mathematician of world-historical importance.

Alan Turing was a prodigy, a genius. A tallish, dark-haired, powerfully built man of twenty-seven with sunken cheeks and deep-set blue eyes, he wore unpressed clothes, picked at the flesh around his fingernails until it bled, stammered, fell into long silences, rarely made eye contact, sidled through doors, ran long-distance races, and had, by the time he arrived at B.P., made two fundamental contributions to knowledge.

He had been born in London in 1912, the son of an English administrator in the Indian Civil Service and a mother who rejoined her husband when Alan was a year old, leaving him and his older brother to be raised by a retired army colonel and his wife on the south coast of England. Despite an undistinguished career at his public
school, Sherborne, Turing was bright enough to win a mathematics scholarship to King’s College, Cambridge. Upon his graduation, his brilliance was recognized by the college, which made him, at twenty-two, one of its forty-six fellows, enabling him to pursue his studies in mathematics.

That field was then in turmoil. A few years earlier, in 1931, the Czech mathematician Kurt Gödel had proved that contradictions would eventually arise in certain self-referential statements that would prevent some problems from being solved; mathematical knowledge would forever remain incomplete. Turing took this idea a step further in a paper published in 1936, when he was twenty-four. He began by envisioning a mechanism that could move to right or to left an infinitely long tape marked into squares and that could read and change or read and leave unchanged the blank or the mark—the 0 or the 1—in each square. He demonstrated that this machine could compute anything that could be calculated. But then he proved that even this device could not tell whether the potentially solvable problems could be solved.

This remarkable paper had two results. It demonstrated that a fundamental problem in mathematics, the so-called
Entscheidungsproblem
—ascertaining whether certain problems could be solved—was not soluble. And, as became evident only later, the imagined device, eventually called a “universal Turing machine,” was the idealization of general-purpose computers. Turing became, in other words, the intellectual father of the computer.

An American mathematician at Princeton had also been working on the
Entscheidungsproblem
, and Turing spent the academic years 1936–37 and 1937–38 at that university earning a doctorate. While there he frequently discussed ciphers, to which he had been attracted since he was a boy. He claimed to have found an answer to the question “What is the most general kind of code or cipher possible?” If he talked about cryptology at the King’s College high table, he may have been recognized as a natural recruit by those Room 40 veterans who
either were still fellows of or retained close ties with King’s. This recognition perhaps led to an invitation to join the course in cryptology, which ran for a week or two at Broadway Buildings. Though many of the other students were mathematicians, a few linguists, including German scholars, also attended. The course may have been more than instructional. When the charming Oliver Strachey took the young men out and gave them a very good lunch at the Travellers Club, it struck one of them that the course sought as much to let the G.C.&C.S. hierarchs look over the recruits as to teach them cryptology.

Even though the war scare preceding the Munich pact in September had been followed by Chamberlain’s promise of “peace for our time,” G.C.&C.S. had Turing and others come down to London for a second course around Christmas of 1938. Afterward, he visited G.C.&C.S. every few weeks to help Knox, presumably in his attack on the Enigma.

In February 1939 G.C.&C.S. advertised for a “signals computer.” A lean young Oxford graduate in mathematics applied. Peter Twinn hadn’t the foggiest notion what the work entailed—and his interviewer talked all around it—but jobs were then hard to come by. Twinn was hired, together with another mathematician, J. C. T. Dryden, and in mid-February 1939 they reported to Broadway Buildings. When G.C.&C.S. moved to Bletchley Park in August, Twinn found himself working as a cryptanalyst side by side with Knox in the Cottage.