Rain fell softly through the dark night as a team of Soviet soldiers started pushing their shovels into the wet ground of East Berlin.
It was more than ten years since the end of the Second World War and 50 men from the Red Army had been instructed to find underground cables that, it was said, were in urgent need of repair.
They didn't have to work long. By 2 AM, after only an hour of digging, one of the Russian soldiers hit something solid with his shovel just two feet from the surface.
Audacious: the route of the tunnel from the Rudow base in East Berlin, Germany. The cables were only 27 centimeters below street level, making the construction of the tunnel very dangerous and open to discovery
The confused soldiers cleaned up a larger piece of mud and stared at a reinforced concrete roof. They broke a small hole and then a larger one and carefully looked inside. Under their feet lay a room that inexplicably contained cables and a trap door.
Unearthed: a photographer in the tunnel after it was opened by the Russians for public tours
It was a much more important find than they or even most Soviet generals could ever have imagined – their excavation had discovered the most daring Western intelligence plan of the post-war era.
Eight years earlier – almost overnight – the United States had suffered the worst loss of intelligence in the history of the Cold War. For years, they intercepted and decoded Soviet radio communication and collected valuable secrets about the military capabilities and intentions of the USSR. Then the Soviets suddenly changed their code systems and the game was over. The coding systems of the codebreakers went dark one by one.
The Soviets had switched to a much safer method of communication – encrypted messages sent via cables and landlines – and the consequences for Western intelligence collectors were catastrophic.
Only later would America find out that their espionage program had been betrayed by two Soviet spies, one of them Harold "Kim" Philby – a member of the notorious circle of agents recruited by the KGB at Cambridge University.
The intensity of the intelligence failure was so great that the Americans were completely blinded when the Soviet-backed North Korean army invaded South Korea in June 1950. Now the West was terrified that a new war was looming and they could not know what the Red Army was planning.
In the midst of this increasing tension, American and British intelligence services came under pressure to find a new way to penetrate into crucial Soviet communication.
The answer they came up with was Operation Gold. The plan was breathtakingly risky and yet ingenious: dig a tunnel in East Berlin occupied by the Soviet Union and tap the fixed communication that came from the Red Army headquarters.
The tunnel must be 1,476ft long – 20ft longer than the height of the Empire State Building in New York – and extend below and beyond the heavily guarded border.
It should intercept a series of cables that ran almost parallel to the border along a main road. The cables were only 27 centimeters below street level, making the construction of the tunnel very dangerous and open to discovery. It is clear that the entire project must be carried out in complete secrecy. It was the largest secret operation that the American Central Intelligence Agency (CIA) and British Secret Intelligence Service (SIS) had ever carried out.
Traitor: George Blake, who smuggled tunnel plans to the KGB
But there was an even more dramatic turn: they were betrayed, and the Soviets knew about the daring plan before construction even started.
The cause of the leak was the Soviet mole George Blake who, while working for the SIS, smuggled plans for the so-called Berlin tunnel to the KGB.
Blake, codenamed Agent Diomid, spent a decade passing Western secrets to the KGB, and his flood of information contained, unforgivably, the names of other agents working for the West behind the Iron Curtain.
In September 1953, Blake worked at Section Y, a new SIS office in London, where the emphasis was on the ability to tap Soviet landlines. As a respected member of the team, Blake became familiar with his highest-quality intelligence.
One day in January 1954 he boarded a double-decker bus armed with confidential notes from a SIS-CIA meeting about the tunnel and a sketch of the plans. KGB handler Sergei Kondrashev was waiting for him on the upper deck.
Stunned by the significance of the material, Kondrashev placed it in his inner pocket. He would later describe how he felt & # 39; it burned in my chest & # 39 ;. It was explosive information, but it left the KGB with a dilemma. If they tried to protect their communications or even block the tunnel, Western intelligence services would immediately suspect a betrayal – and Blake would almost certainly be an obvious candidate.
It meant astonishing that the KGB chose not to do anything that would risk losing their most productive agent. No one outside of the KGB leadership was told about the tunnel or the role of Blake in its discovery. It meant that Britain and the US could collect a wealth of information on a scale that had never been seen before.
DIGGING started in Rudow, a remote corner of West Berlin, occupied by the Americans, in September 1954. The operation had been in the planning of the CIA and SIS for three years, with accurate calculations, practice excavations and the construction of a large warehouse to hide the tunnel entrance and the 3,000 tons of land that would be excavated during the excavation.
Construction equipment – including a steel liner, a mini forklift truck and hydraulic equipment – was covered with rubber to minimize ringing noises.
The scale of the tunnel was such that there was skepticism in Washington and London that this was even possible. "No one had ever tunneled 1,476 feet under clandestine conditions with the expectation of hitting a target two centimeters in diameter and 27 centimeters under a German / Soviet highway," later a CIA history.
The team set up three six-person crews who dig around the clock by hand, with each crew taking an eight-hour shift. They used trenchers for the army – short-shovel shovels normally used for digging foxes. Complications were experienced almost immediately. The flood table in the area meant that the tunnel had to be built much closer to the surface than planned, making the potential easier to detect.
But in February 1955, after only six months, it was complete.
Now it was time to bring in "the Mole" – an ingenious vertical excavator designed by a team of British Royal Engineers.
Working from the Mole, the engineers could gently drill an inch or two into the ground in the roof of the tunnel, subtly searching for the telephone cables above it. After a few tense weeks, the team discovered the valuable Soviet lines.
This led to the arrival of another crack team of British technicians from the Special Investigations Unit of the General Post Office, who had designed a "tapping room" to amplify signals intercepted by the cables. In the sweaty, claustrophobic room at the end of the tunnel, a "spur" cable was meticulously attached to each Soviet wire and fed to the amplifiers.
Back in the warehouse, translators with headphones connected to equipment in the tap room listened carefully.
Suddenly there was a voice.
"Da?" The Russian voice asked.
"Tovarishch Polkovnik?" A second voice answered – "Comrade Colonel?"
The team had won the jackpot.
A message announcing their success was sent to London and Washington: & # 39; The baby was born & # 39 ;.
It was like finding an oasis in the desert. All of a sudden the Allies had access to detailed information about the Soviet army and air force, weapons, equipment, plans, combat readiness, personnel and military administration. An industrial-scale operation began to transcribe the approximately 1300 calls that are intercepted every day. Some, such as those that explained new call sign and coding procedures, were invaluable. But the most useful calls were those involving high Soviet officers who had problems with their phones.
SIS officer Peter Montagnon recalled: "All normal caution – saying things in a code – would fail and they would just discuss what was going on in a clear, clear Russian language. We would hear more abusive words than anything. & # 39;
Indeed, one of the greatest challenges for the translators was dealing with the amazingly productive and creative curses of the Russians.
A glossary has been created with the label TOP SECRET OBSCENE.
Many reports were "gloomy as hell," as Montagnon said, or slightly amusing, with the Soviets "largely talking about sex and the incompetence of their officers."
While some of what was gained was encouraging, including military deficits and budget problems, other information was worrying.
The West learned that the Soviet Air Force in East Germany had improved its nuclear delivery capacity and was armed with new bombers and jet interceptors with radar in the air.
Little by little, a mosaic was made of the Soviet war order.
It led the CIA to quadruple its estimate of the production of radioactive uranium-235 by the USSR and concluded that the Soviets had the capacity to build nuclear weapons with a higher megaton.
But of course the Allies were not the only ones who kept a secret. Soviet intelligence had little idea of how many military, political and scientific secrets were lost. Neither the Soviet leader Nikita Khrushchev, who was well aware of the existence of the tunnel.
And while the Russians continued to do nothing, concern grew as the months passed.
Khrushchev came up with the idea of exposing the tunnel and imposing the blame solely on the Americans, seeing it as an opportunity to drive a wedge between the United States and Britain.
It would support the Soviet story that the United States is the real obstacle to peace. With the Suez Crisis coming, he wanted to get Britain going.
In April 1956, his order finally came – and that Red Army unit was told exactly where to dig for those & # 39; damaged underground cables & # 39 ;.
About 50 men stood in the middle of the night at 3 to 5 ft intervals along the Schonefelder Chaussee road and started digging. The faucets were switched off after 11 months and 11 days.
The Allies considered blowing up the tunnel to prevent the Soviets from coming through, but, fearing the start of a war when Russians were killed, decided not to do anything.
They were convinced that the Soviets would suppress the knowledge of the tunnel instead of admitting that Western intelligence was capable of such a successful operation of this size. But there was another surprise to come.
Not only did the Russians announce the discovery of an "American spy tunnel," journalists were invited to see it for themselves. It was later opened seven days a week from 9 a.m. to 5 p.m., with a free 30-minute tour. In October 1956, when the most unique tourist attraction in Berlin was finally closed, about 90,000 visitors had visited the tunnel.
reaction in the West was not what Khrushchev or the East Germans had expected.
The US decided not to say anything, which was generally seen as a recognition of responsibility.
Western media usually produced admiration stories for the Americans. Prime Minister Anthony Eden gladly embraced the fiction that Britain had not played a role in the escapade.
SIS was instructed to closely monitor the country's involvement. But behind the scenes, the CIA and SIS carried out an urgent investigation to determine whether the tunnel's discovery was accidental or if the operation had been betrayed.
It was a tense time for Blake. Analysis of the bugged conversations, however, has provided no evidence that the Soviets were aware of the tunnel. He was off the hook – until the revelations five years later of a Polish defector, Michael Goleniewski, who eventually identified Blake as a double agent. He was sentenced to 42 years, but escaped from Wormwood Scrubs in 1966 and reached the USSR. He is now 96 and lives in the Moscow area.
However, neither the betrayal of Blake nor the discovery of the tunnel prevented it from being one of the most successful intelligence operations of the Cold War long before reconnaissance satellites and other advanced systems were in use.
The 40,000 hours of telephone calls were further transcribed in the coming two years and remained usable for the next decade.
Perhaps the most valuable intelligence of all was proof that the Soviets were not preparing to launch an invasion of Western Europe – crucial at a time when tensions between Russia and the West were constantly in danger of overflowing to a real, perhaps nuclear, conflict.
The information collected in the tunnel protected millions of lives, an advantage that can never be underestimated.
© Steve Vogel, 2019
- Betrayal In Berlin, by Steve Vogel, is published by John Murray, for £ 25. Offer price £ 20 (20 percent off) until October 15. To order, call 01603 648155 or go to mailshop.co.uk.
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