It was a bright sunny day in New Mexico, the sort of dry, hot day that is the hallmark of the American Southwest.  The intense sun reflected off the light tan buildings, blinding anyone out in the noonday sun without sunglasses.  On a small attractive bridge situated in the heart of Santa Fe, two men met.  One was in short sleeves and khaki slacks, of average height, slim and somber, with steel-rimmed glasses and clip-on sunglasses.  The other was short and dumpy, incongruously wearing a fedora and a raincoat. He was dressed inappropriately for the desert heat, and was squinting against the bright sun and its reflection off the bone-dry buildings. 

They came together on the bridge, in full view of anyone who would care to glance their way. No one noticed them ─ they were merely two of the many strangers that had appeared in Santa Fe during the war years.  However, on this June day in 1945, this apparently innocent meeting was not a casual happenstance.  The taller of the two men handed an envelope to the short, fat easterner.

It contained the principal elements of the design of the atomic bomb.

This was not the first time the two had met.  Five or six times prior to the meeting on the bridge in Santa Fe, the taller man had given the shorter one envelopes containing scientific documents.  These other meetings had been in New York.  Most of them were brief, lasting only a few minutes.  The two men did not really know each other. The short man ─ the courier ─ was known to the taller man only as “Raymond.”  In New York, four days after the meeting in Santa Fe, the courier delivered the envelope to his Russian contact, just as he had delivered similar packets of secrets after other meetings.

The detonation of the atomic bomb at Trinity (CORIBS)

A month after the Santa Fe meeting, in July 1945, the Trinity Test ─ the explosion of the first atomic bomb ─ took place in the New Mexico desert.  The taller man watched the momentous event from the bridge, five miles from the desert explosion. After all, he had a vested interest in this unique detonation.  He had helped to make  this new and terrible weapon.  He watched as a column of orange fire blossomed into a huge, white mushroom cap.  A month after that, in August, the United States dropped the atomic bomb on Hiroshima.  The nuclear age was now official and public.

Then, on September 23, 1949, four years and a month after Hiroshima, President Truman announced that the Soviet Union had detonated an atomic bomb.  The exclusive possession of the greatest weapon of mass destruction then known to man was no longer the sole province of the United States.  The Cold War now had a new element ─ the concept of shared mutual destruction.

How could this be?  American scientists had assured the president and his advisers that Russia’s development of the atomic bomb was at least two years off, perhaps as many as five years in the future.  Could the Russians have been making more rapid scientific progress than we believed?  More significantly, had they somehow stolen our secrets?

A few months after the Russians tested their atom bomb, a British physicist who had worked on the Manhattan Project ─ the American atom bomb ─ at Los Alamos, New Mexico, and who was now the assistant director of the British atom bomb project at Harwell in England confessed that he had indeed been passing atomic secrets to the Russians.  He  was the taller man from the bridge.

Klaus Fuchs at Los Alamos

His name was Klaus Emil Fuchs, and he was, as it has been shown by history, the most important atom spy in history.  Not any of the notorious names in the saga of the theft of the atom bomb secrets ─ Allan Nunn May, Julius and Ethel Rosenberg, and David Greenglass ─ had been as important to the Russian effort as Klaus Fuchs.

Even the famous Cambridge University spies ─ Philby, Burgess, Maclean, and Blunt ─ had not done as much damage to American and British secrecy.  Only a young American named Theodore Hall, working at Los Alamos during the same period, provided as much information as Fuchs, and then only to confirm what Fuchs had delivered to Raymond, the short courier.

Who was Klaus Fuchs?  What motivated him to betray Britain, his adopted country and her allies?  What exactly did he give the Russians?  What makes up the personality and psyche of the greatest of the atom spies?  How was he caught?

With the exception of the last of these questions ─ how he was caught ─ there are only partial answers.  Fuchs was, as Winston Churchill said of the Soviet Union, “an enigma wrapped in a mystery.”