Atomic Heritage Foundation

In partnership with the National Museum of Nuclear Science & History National Museum of Nuclear Science & History

The British Mission

The British Mission

William Penney, Otto Frisch, Rudolf Peierls, and John Cockroft. Photo courtesy Atomic Heritage Foundation.

The British Mission

Bathtub Row in the snow

Chadwick's Advice

  • The British Mission

    The British Mission

    Historian Dr. David Kaiser explains the important role many British scientists played in the Manhattan Project, from Nobel Prize winner Sir James Chadwick to Soviet spy Klaus Fuchs.

    Narrator: The Manhattan Project was truly an Anglo-American effort. In 1939, Sir James Chadwick, Rudolf Peierls and other British scientists began exploring how to create an atomic bomb, and urged their United States counterparts to join them. As MIT professor David Kaiser explains, the physicists who were part of the British Mission in Los Alamos made valuable contributions. Unfortunately, not all of them were trustworthy.

    David Kaiser: The British actually had been, as with radar, they had been ahead of the game—certainly ahead of the Americans—in thinking about the implications of nuclear fission, possible wartime weapons, devices, bombs, that could be made. There were at the time top-secret calculations done by British researchers on, what would the critical mass be? How much enriched uranium would one need to build a runaway nuclear explosion, to build a bomb?

    There was all kinds of knowledge and expertise on a fairly small scale, before the Manhattan Project really got up and running. And then, many of those figures were able to come over and work at various sites across the United States during the war.

    Sir James Chadwick, who was famous for discovering the neutron, an experimental physicist who brought his expertise. Rudolf Peierls, himself an émigré to Britain from Central Europe, and then he came over and further helped the war effort here in the United States.

    As we now know, they also brought people like Klaus Fuchs, who was another German émigré who had naturalized in Britain, and then came over to work both at Oak Ridge with the efforts to separate isotopes of uranium and eventually made his way to Los Alamos as well. That’s relevant because as we now know, Fuchs was sending information to his Soviet handlers throughout the war and continued to do so even after he went back to Britain, working on the British nuclear program, throughout the late 1940s. 

  • Chadwick's Advice

    Chadwick's Advice

    British physicist Anthony French remembers Sir James Chadwick’s advice on how to dress for American weather.

    Narrator: Sir James Chadwick led the British Mission’s group of accomplished physicists in Los Alamos. Anthony French remembers Chadwick’s advice on how to prepare for life in New Mexico.

    Anthony French: Chadwick was a very taciturn man. He was given to sitting for minutes puffing on his pipe before saying anything. So we didn’t learn much from him.

    One amusing thing that happened actually was, he more or less told us that we were going to a place in America. He said, “Now the winters are rather severe, and you had better get yourself a really good overcoat.” That was about the size of it.

    I followed his advice and bought an expensive tweed overcoat, which I never actually wore. New Mexico weather wasn’t quite that severe at all, even on the top of the mesa. 


Quick Fact:
The British Mission was made up of scientists from Britain who contributed to the Manhattan Project. Many were refugees from other European countries who had fled their homes to escape the Nazis.