181. The Imitation Game: How Alan Turing Broke Enigma (Ep 1)

16:58David:They will change the way they wire them. They will change the way they use them. So it's at this point, it's a very fragile hold that they've got on elements of enigma through 1940, which they are nervous about. And that is the secret of Bletchley Park. And that is the question, which is, do you trust the Americans to tell them?

17:17Gordon:And what do the Americans actually bring to the table as they come over to Bletchley Park? So maybe there, let's take a break. And when we come back, we will look at those Americans and what they are bringing to Bletchley Park. I see you.

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18:30David:Welcome back. So, David, we've looked a bit at the British success at code breaking. the work here at Bletchley, intense secrecy to use the bombs to try and crack the Enigma code. What about the Americans? How good are they at code breaking?

18:49Gordon:Well, I guess the bottom line is that maybe not quite as good as the Brits at this time, which pains me to say, but it is probably worth going back a bit to set up the context behind American code breaking as we get toward Bletchley. So the mission at the time will be known as the Sinkov mission. That's the one that comes here in February 1941. Led by Abraham Sinkov. Now, a decade earlier in 1930, Sinkov had been introduced to code breaking by William Friedman. Friedman himself is a very fascinating character. He's this kind of flamboyant son of a Hungarian-Russian-Jewish immigrant. And Friedman had taken charge of this very tiny unit inside the army called the Signal Intelligence Service.

19:33Gordon:And he has three young recruits that he brings in with him. Sinkov is one of them. Another one's Solomon Kolbach. They're close friends, classmates from Brooklyn. There's another guy named Frank Rowlett. They're all mathematicians. So they're not the crossword puzzlers of old. In 1930, Friedman takes his protégés and shows them a secret, really one of the kind of crown jewels of American code breaking at the time. Friedman takes him down the stairs, second floor of what's called the munitions building, goes into this deserted corridor, stops outside, and then pulls out a small card from his coat pocket.

20:13And it has a combination.

20:15Gordon:He opens a combination lock on the front of the steel door, swings the bolt open. Behind it's yet another steel door, because it's an older version of a skiff and inside the room is pitch black. Friedman turns the light on. Everything in the room is completely dusty, covered in dust. And Friedman turns to his protégés and says, welcome gentlemen to the secret archives of the American Black Chamber. Good name. Which is a great name, by the way. It feels like it was a real miss to not have the American Signals Intelligence Agency called the Black Chamber because that would be a great recruitment tool.

20:54Gordon:So Friedman basically explains that this room contains the working files, the archives of what had been America's really premier and only signals intelligence service up to that point. Now, the Black Chamber had been the creation not of Friedman, but of a guy named Herbert O. Yardley. Yardley is a kind of hysterical character in and of himself. Very colorful guy. He's bald. He's very short. He's very hard drinking. He's a skirt chaser. He is a major poker player. Loves playing poker. And in fact, we're going to talk in a minute about some of the other books that he's written. The only one that's still in print is called The Education of a Poker Player.

21:42Gordon:You can still get it today. That's right. So Yardley had started out as a code clerk for the State Department just before the First World War. After the First World War, he convinced his superiors at states and at the War Department to fund an organization that was operating under a commercial front called the Code Compiling Company in New York. And what they did was they spied on diplomatic traffic that's going in and out of Washington of around three dozen countries. Do you know what one of those countries was? Can I guess it might have been the United Kingdom? It was the United Kingdom. Shock.

22:24Gordon:Horror. Horror. Spies. The Americans spying on people. It never...

22:31David:We're always surprised. We might have been spying on you at the same time.

22:34Gordon:So I think it wasn't one-way traffic. It's maybe a moment to set up a bit of the US-UK intelligence relationship as it existed in the 1930s and the run up to Bletchley. I think it's one of the things that makes Bletchley so interesting is that we're recording this in 2026. the US-UK intelligence partnership. It has ups and downs, but it's largely strong. It's almost impossible to imagine a world where it wasn't the case. But in the 1930s, none of the existing architecture for this relationship and most of the organizations that now participate in it didn't exist. And in fact, I mean, the US at that time had no real intelligence community.

23:21Gordon:I mean, there were bits and pieces of signals intelligence and human intelligence, mostly in the military services, in the Army and Navy, very unlike in the UK, where you had a much more mature intelligence community. There's really no established trust as a result between the two intelligence communities on either side of the Atlantic. And in fact, you were spying on us.

23:43David:We were.

23:44Gordon:In New York.

23:45David:Yeah.

23:45Gordon:There is an MI6, essentially front operation running out of what was then called the Passport Control Office in New York. It comes to be known as British security coordination. There is some collaboration with Hoover's FBI in this period against Nazi networks in the States. There's also a lot of spying going on against the US and against the FBI. I mean, it's fascinating because it's really, I mean, it's an influence operation in many ways.

24:15David:That's what I was thinking is there's a bit where the Brits are spying on the Americans. There's a bit where they're basically trying to influence American politics and they should try and get them into the war. And so you're running an operation, which is if in modern terms, planting information, planting stories, feeding in stories to try and get the Americans into the war. So you're right. It's a very odd intelligence relationship at that time and nothing like what we have today as you get to the start of the war. But on this, the American signals intelligence the code breaking what's also fascinating is is they've got this legacy of the black chamber but the black chamber itself is shut down isn't it yeah by the time we get to

25:00Gordon:bletchley this thing is an art you know it's a relic of the past i mean it's why that room is so dusty uh that they go into and it's shut down essentially because the secretary of war henry Stimson says famously, gentlemen, don't read each other's mail. And he kind of shuts the place down once he figures out what's going on, what Yardley's up to.

25:26David:I mean, that's a very prissy diplomat, isn't it? Who's going to go, well, I would never want to know what my adversaries are doing. And so he shuts down Yardley's operation, doesn't he, in 1929. Meanwhile, the so-called

25:38Gordon:gentlemen in the security coordination, British security coordination, the Brits are like, yeah, Yeah, we'll keep spying. Well, I found this fascinating. I mean, so Roosevelt gives a speech in, I think in 1941, where he shows a supposedly captured Nazi map showing their plans for South America and this kind of partition of South America and Central America into different puppet states. And he cites this in a speech. Do you know what it was?

26:08David:No.

26:08Gordon:It was created by MI6 and fed to the Americans to make us concerned about Nazi plans for the Western Hemisphere. Right. So this shows you how immature the U.S. intelligence community is at this point in time, because at the same time you were very cleverly seeding false Nazi maps into our decision making. We have a guy saying, gentlemen, don't read each other's mail. Yeah, we do.

26:36David:So, but, I mean, Stimson shuts down the Black Chamber. And this is so interesting, isn't it? Because it gets shut down in 1929. But then I think it's the War Department go, actually, you know, the State Department might not want this. We'll take it. We'll take it. So we're going to do it, which is where William Friedman comes in, I guess. So American code breaking does continue, we should say, after the Black Chamber is shut down. But by Friedman, who's going to set up a new organization through the 1930s.

27:05Gordon:And the focus for the U.S. in this era is really Japan, and in particular, Japanese diplomatic traffic, where the U.S. will start to have some successes. Now, very interesting, there's a system that the U.S. has codenamed Purple. And this is Japan's highest level kind of diplomatic ciphers. And it has stumped American codebreakers by the late 1930s for a very long time. And it stumped the Brits too. Yeah. Because the Brits have not cracked it.

27:39David:They've all been trying to work against it.

27:41Gordon:Right?

27:41David:Yeah.

27:41Gordon:And finally, though, in the autumn of 1940, the Americans get a breakthrough. Friedman and Sinkov and these guys who've taken over the legacy of the Black Chamber and really focused it, in this case on Japanese diplomatic traffic, have finally been able essentially to recreate the purple machine, the machine that the Japanese are using to encrypt their diplomatic traffic. Now, Friedman ends up having a nervous breakdown on the tail end of this. Probably, it's a little bit unclear, but probably from just essentially overworking himself constantly. And it's a very fascinating story of how Friedman and his team back-solved for the Purple device from intercepted communication.

28:29Gordon:So they didn't have one in their possession. They actually built one out of old telephone equipment. And it constructed this analog version of this Purple machine. And that, I think, it's a very important piece of the Bletchley context, because by the time we get to late 1940, early 1941, the Americans actually have something to offer.

28:51David:Yeah, they've got something to bring to the table. And it is the fact that they've solved the purple machine. They've got their own working version of it. It is interesting, as you said, that Friedman, who's a curious character, does have a breakdown. And it is thought to be related to the stress of trying to break purple as the war is coming. And it started in Europe and obviously not yet. You know, the US hasn't yet been attacked by Japan. That's going to come later in 1941. And it would have been Friedman, I think, coming to the UK in February 1941 if he hadn't had this breakdown and needed to be hospitalized for it.

29:28David:And you get the sense of just the intensity of the work that's been going on within the American code breaking community at that point. It's interesting as well, because they've also had issues about secrecy, haven't they? Because they've got worries about having their truths exposed. Because right at the start, Yardley, to go back to him, had gone public about the black chamber and he'd written a book about it. And so they had this kind of huge exposure of their codes and their information. And so they're also worried about secrecy as a result. And they've also got these fears. So you can see on all these sides, there is this question, well, we've had this breakthrough, a bit like the Brits have had with Enigma, the Americans have had with the Japanese.

30:12David:But do we dare share that with the public?

30:14Gordon:And neither know that the other side has had that breakthrough. It is fascinating, and it really does lend some credence to, I think, maybe British skepticism about how trustworthy the Americans might be. Because I think at one point in the 30s, Yardley went to work for Chiang Kai-shek on code breaking. He essentially leaves. A lot of American SIGINT community at that time thinks that Yardley is a traitor. He's also done, I think, a very damnable thing because he left the intelligence community and he started writing spy thrillers. Right?

30:52David:The Blonde Countess was one. I was reading about the Blonde Countess, actually. I went down a slight diversion of reading about she's someone, I think, who seduces Americans to try and steal their codes.

31:03Gordon:She seduces a balding, poker-playing, short American codebreaker. Apparently, I was not aware of these spy thrillers before we started looking at this series. They weren't a big influence on you. No, they were not. they have been widely panned. I mean, they're not, basically what, basically he wrote them because he tried to write a sequel to The Black Chamber and there was a gag order put on him. The galleys, the advanced copies of his, of his second book were seized. So he couldn't, he couldn't make money off of it. And so he started writing spy thrillers as a workaround

31:42David:to get his story out there. I think the importance of Yardley is the fact that You know, he exposes the fact this black chamber existed. The Japanese actually in the 30s improved their codes because he's revealed they've broken them. I mean, it's a bit like Snowden in its time, you know, Yardley's impact. You know, it's revealing the truth or the reality that code breakers are stealing communications and breaking the communications. And it goes back to that idea of the sensitivity and the importance of secrecy. And also, I think it does make the Brits a little bit fearful because the Americans have just, you know...

32:18Gordon:Is there another Yardley? Is there another Yardley? That might be coming over here.

32:21David:Are the Americans leaky? It goes back to that question about what can you trust them with about your co-breaking successes?

32:29Gordon:The American team that comes over is interesting, isn't it? Because it's a reflection in many ways of the fragmentation inside America's signals intelligence community. because Sinkov and Leo Rosen are both in the army. They're in the signals intelligence service of the army. Friedman's outfit. But with them are two guys from the Navy, Robert Weeks and Prescott Courier. And in many ways, even though they're working for the same government, these two branches of the armed forces have kind of been doing their own thing on code breaking. So there's not a unity of purpose on the American side either as they come over to Bletchley.

33:10David:No, they kind of compete on the American side. Quite a lot of, and this may be familiar to you, fractious competition within the American intelligence community. All 17 of our agencies work seamlessly together. But I think in those days, the Navy and the Army codebreakers did not get on. They also have, it's interesting, different views of the Brits. The U.S. Navy, much less keen to cooperate with the Brits. They see actually this competition between the US Navy and the Royal Navy. So they're worried that any cooperation will actually help the Brits break American codes. Because it goes back to that idea that actually they've all been spying on each other.

33:50Gordon:Well, we obviously have the benefit of coming to this story with hindsight, right? I mean, at the time, it is deeply uncertain if the US is even going to get into the war. Yeah. much less what kind of partnership might exist between the US and the UK on the other side. So, you know, looking back on it, it can be kind of hard to understand, well, why is there so much skepticism on both sides of the Atlantic about sharing? But in that political context, I mean, in a context where in the US, there's still, you know, very powerful isolationist political tendencies, right? There's actually a residual kind of concern about British intelligence going back even to the first world war where you know you you actually were intercepting some of german and mexican communications and leaking them to get the americans involved in the first world which many americans were still frustrated about in the 1930s so the cryptology the cryptanalysis is the most sensitive stuff that's going on on either side of the atlantic so it is very interesting like why does the bletchley visit even come about because neither side actually knows in advance what the other side has broken but it is happening in this bigger context of a lot of technical and scientific sharing that's beginning to open up i think as both countries see a shared sense of purpose in needing to defeat or diminish nazi germany yeah and i think you're right in a

35:24David:way it's surprising it does happen but there's a bit where the code breakers themselves are curious about what the other side is broken the other side is doing and they think maybe we can learn something you know it's a bit like talking to the polls you go oh hang on a sec there's a different way of doing this but then the other bit is i think they have the the political direction from the very top from you know eventually it'll be churchill and roosevelt to try and work together And I think that is important because you've got both those things coming together. And November 1940, in the context of some of these scientific and technical exchanges, you've got the chief of MI6 telling Churchill that there's a desire to talk to them about what they've done against Japan and to learn what the Americans have done against Japan.

36:13David:but acknowledging it would be awkward then to not reveal what bletchley was doing on german codes and he says you know it would be obvious we have something to hide and and churchill agrees and he says maybe we should show a little leg which is one of those you know which is you know we'll just just show him a little bit and i think that is the context as you hit november 1940 ahead of this February 1941 visit is the idea, well, let's just open up a little bit, but not too much. Let's see what we can get from them. But there is one British official, when Churchill says this, adds a telling note to the memo about this discussion.

36:52David:They says, what will they think if they find we've been reading their stuff? You know, so that's the... It's like maybe you don't tell them. Yeah. You know, they might work out that if we've broken these codes, we've broken their codes. So That's absolutely clear right through the 1930s.

37:09Gordon:The four Americans, now Friedman, as we said, stays back because he's had some kind of nervous breakdown. They leave Annapolis, Maryland on a frigid cold day in January of 1941. Their journey itself is kind of an interesting part of the story as well. Yeah, dangerous. Yeah. So they're going to travel on the British battleship King George V. Now, all of these guys were essentially Army and Navy Reserve who then have to be formally called up in order to be able to travel on a foreign flagged battleship over the duration of what will become a two week voyage, a very unpleasant, I think, two week voyage across the Atlantic.

37:50Gordon:They pretend to be Canadian. Lucky them. For the sake of protecting their real identities. It's a promotion, isn't it? Right. It's all right. I'll hold my tongue because we're trying to get some Canadian intelligence guests to come on for our declassified club members, so I will say nothing. One of them, I forget who it is, said that the ruse of them being Canadian fooled no one on the voyage. None of the Brits were confused. The ship heads for the Orkneys at Scapa Flow.

38:21David:Yeah, which is a sheltered harbour at the north of Scotland. and from there the plan is for two flying boats to come and take the four americans and the equipment that they brought down towards the south but the problem is that they've got this equipment in big crates and they've got nearly two tons of equipment and it actually won't fit through the doors of the flying boats they suddenly realize we can't do that we're stuck so instead they go on the neptune a pretty battered old ship i mean barely afloat i think is the honest truth and that comes up to pick them up and it comes down then the eastern coast of scotland and then england problem is this is where it gets dangerous because it gets spotted by a german reconnaissance plane on the way next thing two german dive bombers appear and prescott courier one of the American says, I was trying to eat some soup, but my mouth was so dry I couldn't swallow it.

39:29David:I've never been so scared in my life. We heard a bomb landing on one side and one on the other side, and the ship would bounce out of the water and back down again. Then I heard something that sounded like someone dragging chains along the deck.

39:43Gordon:Did he have a bowl of soup that whole time

39:45David:in his hands?

39:46Gordon:That seems like it's just the whole time he's holding onto the soup. They're bringing with them that reconstruction of the purple device. It's one of the most valuable pieces of technology that the US government has in its possession at that point in time. So, and the problem is, is it destroyed? It's on the deck. It's on the deck.

40:10David:It's on the deck of the boat. And when Prescott Courier talks about the sound of someone dragging chains along the deck that is actually german guns strafing the deck of the boat and firing along the boat where the purple machine is being stored and there's something like half a dozen passes by these german dive bombers and courier thinks god i thought all that gear is stacked up on deck unprotected absolutely unprotected and i was so scared i couldn't go up and do anything about it anyway and he thinks well that's the purple analog gone i mean it's a pretty close run thing but fortunately the bullets don't penetrate into the crates themselves interesting enough this is thought to be one of the first times americans come under fire in world war ii because they're being shot at by germans of course america isn't yet into the in the war it's not till later in the year after pearl harbor and here they are because they're undercover as canadians that they're getting shot at by Germans.

41:14David:And so they're experiencing, and I think this is one of the important things about this visit to Bletchley, and there'll be other moments where they feel this, they're experiencing the reality of war. And they're seeing what it's like to come over the Atlantic at risk from German U-boats and then to see the German planes strafe them as they're on the Neptune coming down the coast. They are seeing that this is the reality of what it is to be a country at war and to be under attack. And I think that's going to have quite a powerful emotional impact on these Americans as well.

41:45Gordon:So then at Sheerness Port, Kent on the southeast coast, they arrive on February the 8th, probably a little bit sort of worked up from the journey. They're met by a gentleman named John Tiltman, and they head here. They come to Bletchley Park, where they will arrive late at night and be served sherry. Now, was the sherry... Why sherry? Was it rationing from... Because I would assume... Maybe this is wrong. Maybe this is my American ignorance. I would assume sherry isn't maybe the first choice in that instance. Do you not drink sherry? Well, I think it'd be like a whiskey or something.

42:23David:You know what? I think whiskey was maybe harder to come by. Okay. But as we started this episode, you've got the head of Bletchley Park, Alistair Dennison, saying to his assistant, get ready for these Americans, get the sherry ready. Because I think that he just knows they need a drink. Yeah, I think that's what it is. I think the fact it's sherry is that's the only drink that they've probably got. And he knows they're going to need a drink. He knows it's going to be a long journey. And he knows, I think that this is going to be a very important meeting. And I think you can, if you go back and imagine what it would have been like at this moment, a lot is riding on this, because you're trying to kind of build cooperation but also you're fearful aren't you because you're fearful about giving away too many secrets how far do you go what do you tell the americans do you trust them with the secret of what's happening inside the huts of what turing has managed to achieve when it comes to breaking

43:19Gordon:enigma well especially from from the british perspective the cracking of enigma could be the difference between life and death, being able to survive 1942 and 1943. And then also, frankly, and we'll talk more about this in the next episode, the impact, but the number of people, soldiers, civilians, otherwise, who could be potentially saved if you crack this code is very significant. And so as the Americans arrive, I mean, it seems, again, in retrospect, inevitable that it would be shared. But if you share it with the Americans and then you have another Yardley situation and it gets leaked. It's probably the most important piece of technology that your country has, the most important capability.

44:08Gordon:So when the Americans show up at Bletchley, the plan at that point is, as Churchill said, to show them a little leg, but not to share Enigma. Yes. And that's the crucial fact, is that night in February, when they come up the drive,

44:23David:when the sherry is waiting, the plan is not to tell them about Enigma and the breakthrough that's been made by Turing and by others here at Bletchley Park into breaking the code there. And so that is the key question, which is what will happen during this visit? And can you trust the Americans?

44:45Gordon:That sounds like a proper cliffhanger there, Gordon. Let's end it there. And when we come back next time, we will see if you actually can trust the Americans.

44:53David:A reminder, though, that if you want to hear that episode straight away, you can if you're a member of the Declassified Club. And you'll get access as well to the bonus episodes, including a Q &A here at Bletchley Park. And we've got some other great material coming up and some big series and some very exclusive interviews. So do join up at therestisclassified.com. But otherwise, we'll see you next time.

45:15Gordon:We'll see you next time.

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