David Kahn has written a first-rate biography of Herbert O. Yardley, the celebrated (and notorious) codebreaker and poker player, the cryptographic whiz who was, in Kahn's judgment, "the most colorful and controversial figure in American intelligence."
As one of the most distinguished scholars of military intelligence, he is ideally suited to tell the tale.
Why didn't the United States have "an agency of its own to solve and read foreign messages"? "As I asked myself this question I knew that I had the answer to my eager young mind which was searching for a purpose in life. I would devote my life to cryptography."
All in all Yardley was a pretty weird guy.
The Reader of Gentlemen's Mail