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Trinity: The Treachery and Pursuit of the Most Dangerous Spy in History

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Klaus Fuchs knew more nuclear secrets in the last two years of the Second World War than anyone else in Britain. He was taken onto the Manhattan Project in the USA as a trusted physicist - and was the conduit by which knowledge of the highest classification passed to the Soviet Union. When Truman announced at the Potsdam Conference that the US possessed a nuclear bomb, Stalin already knew. This book, by an accomplished scientist as well as historian, is the first to explain the physics as well as the spying, and because Frank Close worked, like Fuchs, at the Harwell Laboratory, it contains much important new material.

528 pages, Hardcover

First published August 1, 2019

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About the author

Frank Close

50 books189 followers
Francis Edwin Close (Arabic: فرانك كلوس)

In addition to his scientific research, he is known for his lectures and writings making science intelligible to a wider audience.

From Oxford he went to Stanford University in California for two years as a Postdoctoral Fellow on the Stanford Linear Accelerator Center. In 1973 he went to the Daresbury Laboratory in Cheshire and then to CERN in Switzerland from 1973–5. He joined the Rutherford Appleton Laboratory in Oxfordshire in 1975 as a research physicist and was latterly Head of Theoretical Physics Division from 1991. He headed the communication and public education activities at CERN from 1997 to 2000. From 2001, he was Professor of Theoretical Physics at Oxford. He was a Visiting Professor at the University of Birmingham from 1996–2002.

Close lists his recreations as writing, singing, travel, squash and Real tennis, and he is a member of Harwell Squash Club.

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Displaying 1 - 21 of 21 reviews
Profile Image for Iain.
Author 9 books120 followers
August 10, 2023
Heavy on detail and meticulously researched, some may get weighed down in the detail about nuclear physics and atomic reactions, but they are key to understanding the role Karl Fuchs played in his work and his betrayal. There's an ominous sense in the destructive power being played with by young men, and the lack of realisation about the future they were creating, and which we live with today (mirrored I think in the people recklessly developing AI today). Alongside Ben McIntyre's A Spy Among Friends about the Kim Philby spy scandal, this is another book that calls into question the reputation of the British Secret Service and Security Service. Again they appear to be either hopelessly useless or willfully idiotic. A fascinating character study and history lesson.
Profile Image for Brian Clegg.
Author 162 books3,172 followers
August 3, 2019
Physicist Frank Close has a kind of dual writing life - which is ideal given he's here writing about the dual life of a German nuclear physicist who was also a Russian spy. Many of Close's books give plenty of detail on a specific aspect of physics - my favourite is his compact title Neutrino, a great introduction to this fascinating particle. However, Close also has a penchant for spy history. He's already given us the story of Bruno Pontecorvo in Half Life, and now we get a biography of the Klaus Fuchs.

A communist from his youth, Fuchs fled Nazi Germany for the UK, where the outbreak of war saw him first treated as a suspicious enemy alien, but his expertise in the suddenly desperately important field of nuclear physics saw him brought into the fold, working on theory for nuclear reactors and atomic bombs, both in the UK and in the US, where he made important contributions to the Manhattan Project. Shockingly, when it all came out in 1950, it was also discovered that most of the time between 1941 and 1949, he was passing nuclear secrets to Russia - and without doubt made it possible for Russia to catch up with the West in its development of nuclear weapons.

This isn't a heavy science book - Close only gives high level details of the physics involved - but instead it features a very detailed history of Fuchs' spying activity and the (frankly bumbling) process by which he was eventually caught. Rather than paint Fuchs in black and white as an evil betrayer of his adopted country, Close gives us a balanced picture that helps understand why Fuchs felt it was important to balance up what could have been total American nuclear world dominance after the Second World War and why his conscience seemed to force him to confess, when he had proved excellent at covering his tracks and dissembling in the past.

I have slightly mixed feelings about the level of detail Close goes into. We certainly get to experience the reality of spying in all its sometimes clever, sometimes pathetic detail - not to mention the goings on at the Harwell nuclear research establishment in the UK, which seemed to have enough bed-swapping to make it an ideal topic for a modern drama series. It is also really interesting to see how MI5 developed from practically nothing to a professional(ish) intelligence agency. However, it did almost feel that Close was too, erm, close to his subject, giving us so much detailed description of conversations, journeys and so forth that at times it could become a touch tedious if not being considered as an academic title.

Another small moan - perhaps because the focus isn't the science, there were a number of scientific typos. For example, chemical formulae are written incorrectly with the number of atoms shown as a straight number rather than a subscript, we're told 100 degrees Fahrenheit is the same temperature as 100 degrees Celsius, and uranium hexafluoride is described as a 'mixture of uranium and fluorine' rather than a compound. All trivial editing errors, but suggesting that the focus was elsewhere.

There is no doubt that Close - who personally knew some of those involved - is ideally placed to tell this story, and does so with immense care. This was a crucial period in the development of the modern world, and whether or not Fuchs deserves the cover epithet of being 'the most dangerous spy in history', it's a story that is still important today.
Profile Image for John Gribbin.
165 reviews110 followers
October 27, 2019
If you like the books by Ben Macintyre about the real life activities of 20th century spies, you will love this. Frank Close is a nuclear scientist and author of several excellent books of popular science, so who better to tell the story of Klaus Fuchs, the man who gave the secrets of the atom bomb to the Russians in the 1940s? The science is impeccable, as you might expect, and I now know how to make a hydrogen bomb. But the personal story is even more interesting, and leaves this reader at least with a great deal of sympathy for Fuchs, whose motives, given his personal background and the situation at the time, were much more honorable than the usual portrayal suggests. It is also a bit of an eye-opener (without giving too much away) to realise how much his work at Los Alamos "unofficially" helped the British. Most eye-popping of all, though, is the sheer incompetence of the members of MI5 who overlooked his activities for so long.
613 reviews2 followers
January 14, 2020
Somehow I just couldn't get into this book. Maybe it was because I was lost in the technical aspects and didn't fully appreciate what Fuchs knew and how much harm his spying did. Actually the back story is that his objective in passing on the information was to ensure mutually assured destruction, and by ensuring MAD he may have just ensured that the world never again used nuclear weapons. Besides being lost in the technical details, I thought there was a lot of repetition and the book could have been a lot shorter and still covered what was needed to understand Fuchs and his actions.
3 reviews
August 19, 2019
Excellent book but a bit too detailed

A very important book. Extremely well documented but too detailed for the general reader.
Fuchs was idealistic but not realistic.
Profile Image for Laurence Westwood.
Author 5 books20 followers
February 29, 2020
In 1949, the Soviet Union exploded its first atomic bomb. In 1951, the US Congressional Committee on Atomic Espionage concluded, ‘[Klaus] Fuchs alone has influenced the safety of more people and accomplished greater damage than any other spy not only in the history of the United States, but in the history of the nations.’ Trinity by Frank Close is the story of the spy Klaus Fuchs, of how he arrived in England as a refugee from Nazi Germany just prior to the Second World War, of how the theoretical physicist Rudolf Peierls recognised Fuch’s mathematical brilliance and invited him into his home and into his laboratory, of how the pair of them at the University of Birmingham were the first to develop the theoretical underpinnings of the atomic bomb, of how they both went to work for the Manhattan Project at Los Alamos under Robert Oppenheimer, and of how Fuchs came to betray Rudolf Peierls, his fellow scientists, and his adopted country by leaking all the details of this work to the Soviet Union. Trinity was the codename for the test explosion of the atomic bomb in New Mexico. But Frank Close also uses the term in this book to refer to the bomb’s metaphorical father, Rudolf Peierls, his intellectual son, Klaus Fuchs, and the ghosts of the security services in the UK, the US, and the USSR.

Frank Close is a theoretical physicist himself and he brings to this story not only his own knowledge of the physics involved in the design and building of first the atomic bomb and then, subsequently, the building of the hydrogen bomb, but also his personal recollections of Rudolf Peierls, having once worked for him as a graduate student back in the 1960s. This accounts for the unusual (but very effective) framing of the book, in which Frank Close not only focuses on the Klaus Fuchs, the science, and the espionage, but also the very important human relationships: the people known to Fuchs – those who depended upon Fuchs, and those on whom Fuchs depended – who were so badly affected by his betrayal.

First off, this is not an easy book to read. It is certainly not for the faint-hearted. It reads more like an academic history at times. If anyone is expecting a spy thriller in the style of Le Carré (as oddly stated by a review quote on the dust-jacket) they will very likely be disappointed. Instead, this book is a highly detailed, forensic examination of Klaus Fuch’s work, his espionage and the sometimes farcical investigation conducted by the Security Service (MI5) into his activities. Though the book is challenging in terms of all the detail presented – very possibly, too much detail – it never ceases to be both fascinating and humane. The story is, of course, a tragedy of epic proportions. Klaus Fuchs was not coerced into espionage by agents of the Soviet Union. Once a member of the communist underground in Germany and fanatically anti-Nazi, he freely offered up to the Soviet Union all the details of his work on atomic energy and atomic weaponry. And, after seven years of betraying all around him, he had become an excellent spy, and very careful at all times. Even when arrested he was prepared to only give up the names of his espionage contacts once he knew that they had also been arrested or were out of danger of arrest themselves. He was, by all accounts, a very decent man who cared deeply about his friends and colleagues.

It remains unclear quite why he supplied the Soviet Union with atomic secrets, whether it first began because he hated and feared Nazi Germany so much and was naïve in his understanding of the Soviet Union, but what is clear is that by the time of his arrest in 1950 in England, he had grown to love his adopted country and hoped – again, naively – that after explaining to the MI5 officers just what he had done, he could continue his work on atomic energy and atomic weaponry in the UK as if nothing really had happened. It was only when he had received a letter from the wife of Rudolf Peierls while awaiting trial in Brixton Prison, a letter that held nothing back in regard the feelings she had about his betrayal that he probably began to understand the true depth and scope of what he had done. He served 14 years in prison. On release, he travelled to the German Democratic Republic (East Germany) and continued with his academic work there. He never visited England or communicated with Rudolf Peierls again.

As I have said, for you are looking for a gripping, fast-paced narrative, this is not a book for you. If, instead, you are looking for a highly-detailed examination of the life of Klaus Fuchs, the science behind the atomic bomb, Soviet espionage, and the work of the Security Service in the UK to counter Soviet espionage during the 1930s, 40s and 50s, then I highly recommend this book.
95 reviews
February 14, 2020
A well written and detailed history of the passing of British and American atomic secrets to Russia, and American secrets to Britain, by nuclear theoretician Klaus Fuchs.

The book is particularly exciting and tense in the middle parts where it describes Fuchs' espionage activities. It is also fast paced as the path narrows to his admission and arrest.

Descriptions of the scientific concepts are concise and well done, and made interesting in context so they should not trouble a general reader. A few simple diagrams might have helped.

A large amount of research in primary sources and synthesis of earlier histories is included with rich referencing. A stylistic choice was made to also use extensive footnotes which adds interest but can be a little over-eager and risks being distracting.

Atop the storytelling is an attempt to understand the motivations of the players in this saga. Many of these such as MI5's errors and denial, the FBI's self-aggrandisement and the betrayal of fellow scientists are obvious. However, there is also an interesting contrast between the choices of Peierls to engage in public debate versus Fuchs to distribute information that could have been explored more by giving some more compemporary context.

The main criticism is that the book abandons objectivity about some of its subjects. It is highly positive towards Peierls and Arnold, but unapologetically scathing about Hoover and Skardon. Some individuals such as Jane Sissamore/Archer and Laura Arnold seldom appear without association of a loaded adjective. This is probably an inevitable consequence of the author knowing a number of the characters personally and professionally, or having met them later in life.

The book does attempt to portrary Fuchs' motivations and particular sense of honour without simplistic morals. It is very difficult for us to appreciate the strong political forces, the heady intellectual atmosphere, the foresight of uses for the energy, and the dread of annihilation that surrounded the early development of nuclear technologies for war and peace.
Profile Image for Yasir Noori.
41 reviews
December 30, 2019
I chose to listen to the book because it was featured in Nature's (the science journal) list of top ten books in 2019 (link below). While the list is described as "reviews of the essential science reads of the year" I don't think the book is really a science read. It is a mixture of the drama related to the story of Fuchs espionage activity and the science which he contributed to or worked on, particularly Nuclear bombs and nuclear reactors. Although I am a Physicist, I have learned several scientific things from the books related to enriching uranium, and the make of the super H-bomb.

I found the book to be a bit too detailed regarding the investigation of Fuchs. It describes in too much details his days and the activities of MI5 personnel between 1949 and 1950. However, it gives a very good impression of how lengthy and tedious such a processes can be, which I may not appreciate from watching similar stories through movies or documentaries.

I personally would have preferred to see more details of the technicalities of making the trinity bomb and the technicalities behind deciphering the messages obtained from the Venona project. That would make the book a bit less focused on the life of Fuchs and more interesting scientifically.

https://www.nature.com/articles/d4158...
Profile Image for Laurielib.
630 reviews11 followers
October 15, 2019
Trinity by Frank Close is a fascinating look at the development of the Atomic Bomb at Los Alamos. Seen through the eyes of a spy, Klaus Fuchs, who for eight years gave the Soviets all the information on the development of the bomb. In fact due to Fuch’s efforts Stalin knew all about the bomb before President Truman. Fuchs was central to the creation of the bomb from its theoretical conception in the UK to the test explosion at the Trinity Site in New Mexico and beyond as the key player in Britain’s development of nuclear power. Fuchs is a fascinating psychological study whose motivations were a belief in the purer aspects of Communism, maintaining equality among the superpowers and a hatred of Hitler’s Nazi Party. His conviction in the UK is a fascinating legal drama that leaves the reader with many unanswered questions. While most of the physics were over my head I appreciated Close’s detail. We’re visiting the Trinity Site in October and this book makes that trip even more exciting.
78 reviews
June 1, 2020
This is a meticulous accounting of the life, career, arrest and fallout of British-naturalized citizen Klaus Fuchs, a German-born spy who gave secrets about the atomic bomb and atomic energy to the Soviets during a 7-year period in the 1940s. The author, Frank Close, a nuclear physicist himself, provides a detailed history of Fuch’s anti-Nazi, Communist leanings and why he became a spy. It also is a window into the early days of how spy agencies operated, before the Internet and cell phones, when the use of phone wiretapping and bugging rooms was just getting started, and provides insight into how the FBI and the early CIA interacted and shared (or didn’t share) information with their British counterparts, MI5 and MI6. It’s a story of a man who, in 1951, was described as causing ‘greater damage than any other spy’, and a very good read.
Profile Image for Ralph Burton.
Author 61 books22 followers
March 23, 2024
Klaus Fuchs has gone down as a historical villain but in a world where thousands of missiles are pointed at each other either side of the Atlantic, his legacy is muddier. He may even be considered a hero. Who knows what the US would have done with total control of The Bomb (though this waas never likely)? It's amazing how much the story of Fuchs mirrors that of Oppenheimer, who was innocent. Maybe for this very reason Frank Close limits Oppenheimer's story in this book -- his name is said, I counted, four times. What I would say is that this is marvelously researched and edited but lacks an insight into Fuchs' inner-psychology, not a flaw of Nolan's Oppenheimer despite Nolan often being dinged for being icy and cold (or just British).
Profile Image for Brian Hanson.
363 reviews6 followers
February 7, 2021
Not only an excellent tale of espionage, by someone who knew some of the key characters, but one of the best accounts (for a layman like me) of the theories and applied science behind the atomic bomb. It's good to be reminded how shittily the US treated the UK over the issue of nuclear energy and weapons - the UK having been indispensable in supporting the development of the fundamental theories. It does make one wonder whether Klaus Fuchs did the world a favour by helping ensure that America did not, in the end, have exclusive possession of the weapon. Could have done with the cool hand of an editor, to prevent the many repetitions.
Profile Image for Carol Ann.
54 reviews
February 18, 2024
This book is a WW2/Cold War spy thriller. Except it really happened! Klaus Fuchs, an atomic scientist who became a spy. It is an incredibly detailed history into how Russia got details for the atomic bomb. A brilliant description of the design of the atom bomb is interesting, if long winded, but I understand the need for this, as it shows what an incredible mind Fuches had. It may well be too detailed for some readers, but it is worth persevering.
4 reviews1 follower
January 7, 2020
Enjoyed the science part, but for me the story of the espionage was too detailed. Facets that, whilst being historically accurate, made it something of a effort to get through. The balance between story and historical accuracy/detail was not best placed for my taste. Excellent research gone into it though and pleased to have read it.
Profile Image for Grant Hodgson.
37 reviews1 follower
February 17, 2021
A fascinating and well told story that leaves one more informed and sympathetic about Fuchs, more interested in the question as to whether Roger Hollis may have been a Soviet mole in MI5, and somewhat more despondent at the willingness of top scientists and politicians to pursue the development of such insanely destructive weapons as the H-bomb.
42 reviews
December 8, 2022
An interesting story but a repetitive book.

Frank Close clearly did a ton of research, and it was interesting getting an authentic look into spy craft and counter espionage in the 40's and 50's. But the book was a continual circle of poor investigations by MI5 and simple information drops by Fuchs.
Profile Image for F.R..
Author 37 books221 followers
May 17, 2025
For someone who only knew the broad outline of the Fuchs case, this was a fantastic telling of the story - even if it did occasionally lose me when trying to explain how the physics work.

The stakes might have been huge, but the real, flawed human beings are always at the centre of this tale.
Profile Image for Mike.
101 reviews
January 13, 2020
One of the best spy books I have read, very detailed but it moves along quickly. It was hard to put it down
54 reviews2 followers
April 9, 2021
A very detailed account of Klaus Fuch's activities.
Profile Image for Chris.
521 reviews
August 24, 2023
An excellent and very detailed account of Fuchs: his origins, work and finally exposure - in which a meeting in a pub in our village had a small but vital part.
Profile Image for Ellen.
1,206 reviews7 followers
November 19, 2023
Pacy for the most part. It lost a bit of steam in the last 70 pages or so.
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