Herbert O. Yardley

(Photo taken at the National Cryptologic Museum located at Fort Meade in Maryland)

In his book "Best Kept Secret", John Bryden writes that '"The American Black Chamber" (1931) is a classic in the annals of secret intelligence. It is mostly the story of Yardley's First World War experiences as the head of the War Department's cryptanalysis bureau. Written in a crisp, anecdotal style, it is a very readable narrative of early code- and cipher-breaking, wireless and cable interception, secret inks, and spy-catching. These revelations were enough to make it an instant best-seller but, unfortunately for him, Yardley went too far.'

It is reported that in May 1941, General Joseph Mauborgne (Chief Signal Officer, U.S. Army) recommended to the Canadians that they hire Herbert Yardley whom he described as "an expert cryptographer and fine organizer". Yardley worked for the Canadian cryptographic section from June to December 1941. There had been great pressure by the U.S. and U.K. to have him dismissed.