Operation Epsilon

This was a Allied undertaking at the end of World War II in which 10 German scientists, all believed to have worked on Germany’s nuclear programmes, were held at Farm Hall, a house in Godmanchester, England, fitted with secret microphones and recording equipment (3 July 1945/3 January 1946).

The object of the undertaking was to determine how close the Germans had been to constructing an atomic bomb. The results of the transcripts were inconclusive, and all of the scientists seemed to be genuinely surprised when informed of the US atomic bombing of Hiroshima on 6 August 1945. The transcripts seem to indicate that the physicists, in particular the quantum physicist Werner Heisenberg, had overestimated the amount of enriched uranium that an atomic bomb would require, and that the German project was at best in a very early, theoretical stage of thinking about how atomic bombs would work. The transcripts were originally sent as reports to British military officers, and were then forwarded to the US Department of War, from which they were later passed to Lieutenant General Leslie Groves, heading the ‘Manhattan’ Project, as part of ‘Alsos’.