 John Cockcroft became the director of the Anglo-Canadian Montreal Laboratory.The British mission to the Los Alamos Laboratory led by James Chadwick, and later Rudolf Peierls, included distinguished scientists such as Geoffrey Taylor, James Tuck, Niels Bohr, William Penney, Otto Frisch, Ernest Titterton and Klaus Fuchs, who was later revealed to be a spy for the Soviet Union.As overall head of the British Mission, Chadwick forged a close and successful partnership with Brigadier General Leslie R. Groves, the director of the Manhattan Project, and ensured that British participation was complete and wholehearted.