On September 10, 1949, Michael Perrin’s phone rang in the middle of the night. The message was simple, direct, and urgent: come to the American embassy immediately.
Perrin, deputy director of Britain’s longtime atomic energy program, jumped in a taxi for the five-mile trip south from Hampstead to 1 Grosvenor Square, where U.S. State Department officials hustled him into the communications room. There he learned the content of several coded telex messages from the Pentagon. The U.S. Air Force, using specially equipped planes, had detected radiation in the atmosphere. The only explanation could be the explosion of an atomic bomb. The United States needed an RAF plane to conduct additional tests to confirm the findings.
One week later, Perrin gathered with other experts for a meeting of Britain’s Joint Intelligence Committee at the Ministry of Defense at Whitehall. To the surprise of many JIC members, the room was first cleared of secretaries and “anyone else who could not keep what was going to be said to himself,” placing the meeting, as one observer described it, “under a melodramatic bond of secrecy.”
A balding physicist with a serious countenance, Perrin somberly explained that the radiation detected was most likely the result of a Russian A-bomb test, most likely in the area of Lake Baikal. RAF airplanes outfitted with special filters had “obtained particles which have been definitely identified as plutonium,” though he acknowledged that there was still some doubt about the specifics.
The committee approved Perrin and the director of MI6 to brief Prime Minister Clement Attlee at his country home, and the two men hastened up to Putney. But Attlee was already aware of these dire developments. He and President Harry Truman had been in contact by telegram.
Four years had passed since the American bombing of Hiroshima and Nagasaki, and the end of the war had brought a significant realignment of the world’s major powers. Having sided with the Western democracies against the Nazis, the Soviet Union had emerged from the war—at least in the eyes of its former allies—as the greatest threat to the current peace. Joint Intelligence Committee papers had projected that the Russians would have a bomb by 1950 at the earliest, more reasonably in 1952. British military forecasting relied on these assessments. If the radiation was truly from a Russian test, how could this have happened so quickly? How could Soviet science have leaped so far ahead?
In classic understatement, one participant in the meeting noted the significance of the A-bomb test in his diary: “The [Joint Intelligence Committee] papers will, of course, have to be revised.”
Not far from Buckingham Palace, in an unassuming office building of ordinary brick and limestone near Hyde Park Corner, a man sat examining top secret memos that might provide the answer to Russia’s mysterious go-ahead. There was nothing about the man, Arthur Martin, to suggest international intrigue, even less so derring-do. The same was true of the building nestled in among the pubs and grocery shops of Curzon Street—except perhaps for some bricked-in windows. The gun ports on one side might strike an equally odd note for the careful observer. The bricks and the ports had been devised as last-ditch insurance against German paratroopers landing in Hyde Park during the war. The architectural anomalies made sense only if one knew that the unassuming building, Leconfield House, was the headquarters of MI5, the section of military intelligence tasked with hunting down spies on British soil.
The memos in Martin’s care had originated across the Atlantic, where American and British code breakers toiling in Arlington, Virginia, had at long last made sense out of seeming nonsense. They had labored long and hard over a stack of coded messages sent between the Soviet consulate in New York and Moscow in 1944, back when the United States and the U.S.S.R. were closing in on German forces from opposite sides of Europe.
Now, five years later, the decoded threads revealed evidence of a wartime traitor. Urgency and dread pulsated through a telegraph from the British embassy in Washington:
We have discovered Material, which, though fragmentary, appears to indicate that in 1944 a British or British-sponsored scientist working here on atomic energy or related subjects was providing Russians with policy information or documents.
Agent’s cover name was initially Rest subsequently changed to Charles. In July 1944 he had been working for 6 months.
On one occasion he handed over through cut-out report described as M.S.M. -1(part 3) subject of which appears to be fluctuations in stream or ray. . . .
My present opinion is that this will prove grave matter.
Again, British understatement held sway.
Arthur Martin was relatively new as an intelligence officer at MI5, but he had a history with signals intelligence and encryption. He had spent five years at the Government Communications Headquarters securing its systems and examining those of foreign powers. Just recently he had been made liaison between GCHQ and MI5’s B Branch, counterespionage and counter-subversion, a division that was often the focus for high-profile action.
For decades, MI5 had bugged the British Communist Party headquarters, routinely opened the mail of its members, and kept an eye on fellow travelers, and since the war it had doubled its efforts. It worried as it looked to the East. Moscow’s persistent pressure on Central and Eastern Europe had undermined nascent democratic governments. In March 1946, in a famous speech in Fulton, Missouri, Winston Churchill had described the Soviet menace with characteristically memorable prose: “From Stettin in the Baltic to Trieste in the Adriatic, an iron curtain has descended across the Continent.”
In the face of Soviet expansion and propaganda, a weakened postwar economy that included continued rationing for food and gas in particular, as well as an acute housing shortage, made Britain vulnerable to leftist pressure. On the heels of World War II and the Great Depression, the austerity had pushed out Conservative governments and elevated left-wing ones to power, with Churchill sent back into the wilderness and Clement Attlee’s Labour government in control.
A bright spot in the British firmament was science, a positive side effect of weapons research that included development of the atomic bomb. The nuclear age could give Britain the capacity to develop new forms of power and medicine, and new weapons. Many of its top scientists, partnered with their American counterparts, had tirelessly slogged in the Manhattan Project, the joint U.S.-U.K. effort to build an atomic bomb, and now Britain wanted its own. Until the British achieved that milestone, the Americans had a monopoly—or so they had thought before detecting radiation in the atmosphere.
If Russia did have a bomb, and well ahead of schedule, it would shatter the West’s atomic hegemony. What would this portend for the security of Europe, and in particular the security of England? Moscow was only fifteen hundred miles from London. One burdened soul later agonized that with sufficient bombs the Soviets could “blot this country out entirely.”
Arthur Martin chased suspects through clues on paper: studying the messages, reviewing the files, and slowly filling in the pieces of the puzzle. The tighter the pieces fit, the clearer the patchwork scheme became, and the more effectively field agents could operate.
For this assignment, he had to penetrate the clues available in the decoded messages of the Russians and try to ferret out the traitor and what secrets he had betrayed. Hamstrung from lack of information, he could do little until the endless blocks of numbers in the coded messages yielded treasure. He waited.
In a move to lift the veil, British intelligence officers in Washington told Martin that they were keen to dig into the 1944–45 files on the Manhattan Project. Their information was still fragmentary, but using the specifics they had—a scientist, perhaps British or British sponsored, working in the United States on a project probably related to atomic energy in 1944—they thought they could link the clues and identify the scientist who had betrayed them. A week later, they cabled Martin that they had come up empty, and any notion of an easy solution had evaporated.
As the second week of the hunt rolled in, some light peeked through the clouds. The relentless chipping away of the code breakers in Arlington had extracted more information hidden in the blocks of numbers. The embassy sent Martin actual text from ten partially deciphered messages. But with the mixed bundle of fully deciphered sentences, partial ones, and large chunks of code that defied best efforts, he had plenty of head-scratching ahead. A message from New York to Moscow dated June 15, 1944, typified the decoded material he had in hand:
To VIKTOR.
[1 group unrecovered] received from REST the third part of report MSN-12 Efferent Fluctuation in a Stream [STRUYA]
[37 groups unrecoverable]
Diffusion Method—work on his specialty. R. expressed doubt about the possibility of remaining in the COUNTRY [STRANA] without arousing suspicion. According to what R. says, the ISLANDERS [OSTROVITYaNE] and TOWNSMEN [GOROZhANE] have finally fallen out as a result of the delay in research work on diffusion. . . . *
*Only the latter part of the word has been recovered, but “Diffusion” is probable from the context.
The code breakers had to turn seemingly random number blocks into Russian words and then into English, with specific code names requiring identifiers as well. Some of the identifiers were clear—“COUNTRY” was the United States, “ISLANDERS” were the British, and “TOWNSMEN” were the Americans. R, “REST,” was the mystery.
Martin was different from most other officers in counterintelligence. He didn’t belong to the class of “gents” recruited from Oxbridge by way of Eton or Harrow, the toffs who dominated the intelligence establishment. His education was plebeian, and he made no attempt at clubbiness. Baby-faced and a heavy smoker, he kept a bottle of scotch in the desk drawer and drank it out of a coffee cup when needed. But he was a dedicated professional and a lawyer with meticulous focus, good intuition, and an analytical mind.
The director of B Branch, Dick White, had brought him in, and they had a close relationship, both professionally and personally. Martin had married White’s secretary, Joan. Of course, in the symbiotic underworld of spying, the connection didn’t stop there. Before her marriage to Martin, Joan had carried on an affair with White.
Scrutinizing the text of the ten new messages, Martin carefully extracted and listed the certainties along with the uncertainties. He could document that the spy called Rest was male, had been in the United States between March 1944 and July 1944, had worked on an Anglo-American scientific project, had contact with the report “MSN I-Efferent Fluctuations in the Stream,” and had a sister who probably lived in the United States. At least, the sister’s time in the United States overlapped with his. In 1944, an unknown Soviet agent visited this woman in October and possibly again in November. The key uncertainties were the nationality of the scientist, his possible transfer back to the U.K., the location of his sister, and the nature of the scientific project he’d worked on.
The messages indicated that the British had considered transferring their researchers back to the U.K. because of tensions with the Americans. When confronted with this, the Americans countered that it would be a violation of the secret, scientific agreement that was part of the Atlantic Charter, signed by Churchill and Roosevelt. The messages didn’t indicate a decision about the transfer. Had Rest been posted to another position in the United States or sent back to the U.K.? Martin was left hanging.
The British security officers in Washington worked closely with the FBI, the British shuttling between their embassy on Massachusetts Avenue and the FBI’s Washington field office housed in the Old Post Office Building near the White House. They both concluded that Rest had most likely infiltrated the Manhattan Project on the atomic bomb.
MI5 and the FBI agreed on a concerted effort, which was to protect the top secret decoding project Venona, even if it slowed uncovering the identity of the spy. Initiated on February 1, 1943, and continuing for decades, Venona was run by the U.S. Army’s Signal Intelligence Service (later absorbed into the National Security Agency) as a means of decrypting messages transmitted by Soviet intelligence agencies. The longer the Russians stayed in the dark about Venona and the extent of Venona’s access, the longer Washington and London had an intelligence edge. Five-year-old messages could still betray valuable secrets.
Martin met with his counterparts in MI6, the military’s division of foreign intelligence, to pinpoint the best entry into the maze of Rest’s identity. On September 1, the embassy in Washington cabled him that the FBI had identified two possibilities. Following the trail of clues from the report “Efferent Fluctuation in a Stream” that Rest had handed over, they made a breakthrough.
That report had originated from the British scientific team. A particular physicist had written some papers for a research series, and his movements matched Rest’s. The FBI offered up the name of one Karl Fuchs, a naturalized British subject of German origin. According to their information, he had arrived in New York on December 3, 1943, and had then been transferred to Oak Ridge, Tennessee, on August 14, 1944.
The Washington team requested all information on this man. Their main questions: Did he have a sister in the United States? And if so, where was she?
Martin now had a name to work with, except his request for a personal file on Karl Fuchs from MI5’s Registry came back unfilled. Klaus Fuchs, who had been a member of the British Mission on Atomic Energy in the United States, did have a file several inches thick, fattened with hundreds of documents.
The file followed the standard MI5 format. Every letter or memo, every set of notes from a meeting, a phone call, or report, was paginated and clipped in the file chronologically. An index at the front of the file, denoted as “Minute Sheets,” briefly listed each document, its arrival date, and page number. Those privy to the file wrote comments to each other—called minutes—directly onto the index sheets. Plowing through it, Martin could follow the thread of confidential office dialogue to pry into the past interpretations and opinions of MI5 personnel.
MI5 quickly “Y-boxed” the file with a new sticker that overlaid its cluttered cover of stamps and file numbers. This new designation added security and meant that “this file when in transit must be in a closed envelope, addressed personally to the officer. HELD BY R5.” A specific person, rather than the Registry, would hold it to ensure against peeks from curious personnel, mistakes in delivery, and leaks. In this case, that person was Arthur Martin. “Indoctrinating” officers—that is, granting access to the secrets in this file—had to be approved by him or the director general of MI5.
Klaus Fuchs’s security file was one for Martin to ponder. Clearly, Fuchs had kept MI5 busy throughout his sixteen years in England and Scotland—no speedy thumb through here. The details in the hundreds of pages led to vague connections and baffling contradictions. In Martin’s real-life game of whodunit, there was no answer card to correct a wrong guess.
Fuchs had been investigated at least seven times, an unusually high number. Few months passed between 1939 and 1949 without his folder landing on someone’s desk for a review or approval. In Fuchs’s case, there was a work permit in 1941, naturalization in 1942, an exit permit to the United States in 1943, and security clearance in 1946 for his employment at Harwell, the main nuclear research facility in Britain and center for all projects on atomic energy.
The last one was for a position as the head of the Theoretical Physics Division at Harwell. The letter requesting the security clearance explained that “there is, as far as we are aware, only one other person in this country who possesses qualifications and experience of Dr. Fuchs.”
Clearances for top secret jobs and promotions required careful consideration and, on their own, would cause the formation of a security file. As Martin was about to discover, Fuchs’s file had a different origin. MI5 had opened it within a year of his arrival in England.
Sitting in his office in Leconfield House, a supply of cigarettes within reach, Martin began his journey through Fuchs’s refugee life in Britain—the file pages worn, rumpled, and faded after fifteen years of scrutiny by others. The first nine dispelled expectations of typical interoffice squabbles and dictates from those in charge. The naked condemnation contained in this initial information—together with its questionable reliability—was stunning.
The file began with a letter dated August 7, 1934. Four days before, twenty-two-year-old Klaus Fuchs had gone to the German consulate in Bristol to renew his passport, a seemingly innocent activity. He had been studying for a PhD in physics at the University of Bristol for about a year, and his German passport had expired in June. Staff at the consulate took his passport and forwarded it to the German embassy in London. The letter of August 7 was its response to Fuchs. For him to obtain a new passport, the police at his last place of residence in Germany had to certify that they had no objections.
Two months later, Fuchs submitted his request for a certificate to the police in Kiel, his last official residence. Within the week, the German embassy sent him a letter refusing him a new passport. It gave him no reason. Instead, it offered to issue him “a short-term certificate”—one way only—to return to Germany.
Britain had granted Fuchs asylum as a refugee from Nazi oppression. His life endangered in Germany, he couldn’t go back.
Without a passport, Fuchs was stateless, stranded in Britain. It was a status becoming increasingly common to German refugees fleeing the Nazis and relatively easy to change. One simply applied to the Home Office to extend the time-limited residence permit.
Martin requested the Home Office’s records on Fuchs, and they showed that year after year the government had rolled over his residence permits until 1938, when he gained permanent residence without a time limit. The only restriction imposed because of his statelessness was on travel outside the U.K. For this he needed official approval.
What Martin read next suggested more than a citizenship problem. At the time of the passport request in 1934, the German Foreign Office in Berlin had returned Fuchs’s original letter to the consulate. On the back, the Gestapo in Kiel had scrawled a note. Translated, it read,
The Student Klaus Fuchs, born 29.12.11 at Russelsheim was as per card presented here and dated 31.8.31 until 3.3.32 member of the Social-Democratic Party. Here he was excluded 1932. Fuchs joined then the Communist Party and worked for this Party as orator in the election-campaigns. Fuchs was leader of the Nazi commission of the Sea District, the task of which it was to break up the National-Socialist Party.
Under strict confidentiality, the consul had forwarded the denunciation to the chief constable of Bristol, who sent a report to the director general of MI5 and the Home Office:
The above-named German subject landed at Folkestone on the 24th September, 1933, conditionally that he registered at once with the Police, and that he did not remain in the United Kingdom longer than three months. . . . Information has now been given to the Police by Mr. Carl Ludwig Herweg, Secretary to Mr. C. Hartley Hodder, German Consul . . . that Fuchs is a notorious Communist. . . . During his stay in this City Fuchs is not known to have engaged in any communist activity.
Disadvantaged by the fifteen-year gap since the incident, Martin didn’t know how intelligence officers had weighed the chief constable’s paraphrase of Fuchs as “a notorious Communist” against his observation that Fuchs’s record in Bristol was unblemished.
He tracked the critiques through the file’s pages and found that during the war, with Nazi atrocities emblazoning headlines, MI5 had treated this report from the Gestapo as highly suspect—most likely propaganda. For a start, the Nazis lumped all Jews, Social Democrats, and communists together. MI5 analysts awarded Fuchs the benefit of the doubt, especially given that the government wanted and needed his scientific expertise.
Martin skipped through the next eight years in the security file to find another troubling incident. Back in 1942, an MI5 informant had asked whether Klaus Fuchs was “identical with a certain CLAUS FUCHS.” Claus Fuchs was a physicist of about thirty years old, had been interned in Canada, and in the camps became a close friend of a German communist named Hans Kahle, who was very active politically.
The question referred to the British internment of about thirty thousand “enemy aliens” at the outset of the war. Most of these—German and Italian refugees who were not yet naturalized British citizens—were Jewish, like the vast majority of émigrés, although Fuchs and Kahle were not. Wary of the costs of corralling masses of scared and angry young men, the British had simply transferred several shiploads to Canada. The camps there were full-fledged prison compounds: barbed-wire fences, spotlights, and sentry towers. Some had volatile mixtures of Germans: Jews, Nazi POWs, and communists.
Was “Claus Fuchs” the same as Klaus Fuchs? The file gave Martin no immediate response, but digging through the minutes, he did find a later internal dispute that led to a conclusion: Klaus Fuchs had been shipped to Canada. Therefore, Klaus Fuchs and Claus Fuchs were probably “identical,” and thus he was the friend of Hans Kahle, someone whose own security file included charges of being a Soviet agent.
The last document that drew Martin’s attention originated from an MI5 informant who gathered gossip from communist groups in various British cities. The informant, “Kaspar,” had heard that both Klaus and his brother, Gerhard, who now lived in Switzerland, had belonged to the German Communist Party. According to the rumor, Klaus never achieved any prominence in the party, but Gerhard was part of the “German Communist Apparat.” Klaus had fled to Prague and was not involved in political activity there. In the U.K., he was part of “the usual Communist propaganda,” according to Kaspar, but again not prominent. He concluded, “He bears a good personal reputation and is considered a decent fellow.”
Was what Martin had extracted enough? Condemnation by the Nazis; a possible communist friend in an internment camp; and a report from Kaspar that stressed the actions of Gerhard and diminished those of Klaus. Did this give him an understanding of who Klaus Fuchs was? Most of the content argued and reargued Fuchs’s reliability. Forms gave a basic timeline. There were no interviews of friends or colleagues. Voluminous though MI5’s file was, Fuchs the person was a vague figure.
One thing was clear: that during the war everyone knew that Fuchs could be a problem but hoped he wouldn’t be. At a point when bombs pelted England, killing residents and burning cities, an MI5 officer had to decide about a work permit for Fuchs to do secret research. He called a colleague and asked if it was “really serious” if the research ended up with the Russians. Could they “employ someone else instead of FUCHS”? the other person responded. Notes on the conversation read, “I said I thought that was the crux of the matter, and that if the work could not be done properly without FUCHS, we should have to accept such risk as there might be.” With devastation surrounding them, the British desperately looked to science for an edge to victory. After all, Hitler was still on their doorstep and could win. Fuchs received the permit.
Not all agreed with this rationale. One MI5 officer, a hardened veteran of the Battle of Dunkirk, asked “whether a man of this nature who has been described as clever and dangerous, should be in a position where he has access to information of the highest degree of secrecy and importance.” To him, the evidence was enough to bar Fuchs from war research.
Martin read a particularly telling exchange from 1943 when Fuchs needed an exit permit to go to the United States with the British Mission on Atomic Energy. An MI5 officer wrote to Michael Perrin, already a highly respected scientist and administrator with the government’s Department of Scientific and Industrial Research. DSIR was the official employer of the British team in the United States. Was Fuchs scheduled to stay in the United States? MI5 wanted to know. Perrin said no.
A month after the British mission’s and Fuchs’s arrival in the United States, Perrin reversed his reply because Professor Rudolf Peierls, a close colleague to Fuchs and a senior member of the British team, requested that Fuchs remain there. Knowing that some MI5 officers had “slight doubts” about Fuchs, Perrin wanted to ensure that there was no problem. “This is a very important matter vis-à-vis the Americans,” he wrote, “and I want to be quite sure that we do not slip up in any way.”
From the vantage point of 1949, Martin followed MI5’s internal deliberations in the file, one that Perrin wasn’t privy to:
[Fuchs is] rather safer in America than in this country . . . away from his English friends. . . . [I]t would not be so easy for FUCHS to make contact with Communists in America, and that in any case he would probably be more roughly handled were he found out.
Martin saw that the letter Perrin received from MI5 had said much less. It read,
It is considered that there would be no objection to this man remaining in the U.S.A. as he has never been very active politically, and recent reports endorse the good opinion you have of his behaviour in this country.
And then came the caveat, which MI5 had added for Perrin’s eyes only:
It would not appear to be desirable to mention his proclivities in the U.S.A. and we do not think it at all likely that he will attempt to make political contacts in that country while he is there.
The restraint and composure of MI5’s approval belied the serious consequences of a miscalculation. Then, and throughout the war years, the agency’s calm tone of denial covered a sea of doubt.
From Fuchs’s file sprang contradictions built on misinformation and misunderstanding that befuddled MI5’s insight into what drove him. But even if they had grasped the inner sense of justice that dictated his actions, they might have been confused. He came from a world that had to be lived or seen in deep relief to comprehend. For perspective, they might have harked back to the sixteenth- and seventeenth-century religious turmoil of their own ancestors whose beliefs were indestructible in the face of torture and death. Those days of beheadings over faith and hiding holes for priests were not so different from the turbulent times that shattered post–World War I Germany. In this light, they might have understood that it wasn’t science that compelled Fuchs but an unwavering commitment to ideals that grew out of early years engulfed in political strife. That was the root of his story and of his being. That is what they needed to know, but didn’t.
Clearly, what the Brits did know was that they were playing the odds, Russian roulette perhaps. And just as clearly, they intentionally failed to tell the Americans about the bullet in the chamber.