The Interwar Period: 1919–1941

In the period between the two World Wars Americans struggled with the morality and the cost of reading other people’s mail. Herbert YardleyYardley, H.O. created his American Black Chamber and established for the first time that the United States should be in the position to protect itself and further it’s own interests with the use of permanent professional cryptographers and cryptanalysts. William Friedman, working in the Army, established the organization that would be the Army cryptologic backbone during the Second World War. Friedman and the team he put together during the 1930s would move American cryptology into the machine age in both cryptography and cryptanalysis. Despite Yardley’s flaws and failures America would never again be without a cryptanalytic bureau. This chapter briefly examines the professional lives of Herbert Yardley and William Friedman during this period and discusses their contributions to the growth of the American cryptologic infrastructure.