This chapter offers biographical sketches of Otto Frisch and Rudolf Peierls: Their childhoods, educations, early careers, how they came to be together in Birmingham in 1940, their wartime work, family lives, and postwar careers. The changing political fortunes of the wartime British nuclear program are also discussed. Together, Frisch and Peierls possessed just the right combination of experimental and theoretical backgrounds and skills needed to prepare the memorandum.