Synopsis
The Reader of Gentlemen's Mail: Herbert O. Yardley and the Birth of American Codebreaking by David Kahn is a meticulously researched biography of Herbert O. Yardley, one of the pioneers of American cryptology. The book traces Yardley’s life and career, focusing on his role in establishing the first organized American codebreaking unit, known as the Black Chamber, and his contributions to the field of intelligence during the early 20th century.
Yardley’s story begins with his early life in Indiana, where he developed a fascination with puzzles and codes, skills that would later define his career. His entry into the world of cryptanalysis came during World War I when he joined the U.S. Army’s Military Intelligence Division. Recognizing his talents, the government placed him in charge of breaking enemy codes, and he quickly proved his ability by deciphering diplomatic communications. His success led to the establishment of MI-8, the first peacetime codebreaking unit in the United States, which later became known as the Black Chamber.
Under Yardley’s leadership, the Black Chamber flourished throughout the 1920s, secretly intercepting and deciphering messages from foreign governments, particularly Japan. His most notable achievement came when his team cracked Japanese diplomatic codes, providing valuable intelligence to U.S. policymakers. However, despite these successes, the Black Chamber’s activities were not widely known or appreciated outside of intelligence circles.
Yardley’s career took a dramatic turn in 1929 when newly elected President Herbert Hoover’s Secretary of State, Henry Stimson, shut down the Black Chamber, famously stating, “Gentlemen do not read each other’s mail.” This decision abruptly ended Yardley’s official career in government cryptanalysis and left him disillusioned. Struggling to find employment, he made the controversial decision to publish The American Black Chamber in 1931, a book that detailed his work and the successes of the unit. The book became a sensation, revealing to the public the extent of American codebreaking efforts and the vulnerabilities of global diplomatic communications.
While The American Black Chamber cemented Yardley’s fame, it also made him a pariah within government and intelligence circles. Many viewed his revelations as a breach of national security, and he was effectively blacklisted from further cryptographic work in the United States. Despite this, Yardley continued his career in codebreaking, offering his services to the Canadian and Chinese governments during World War II.
Kahn’s biography paints a complex portrait of Yardley—a brilliant but flawed figure whose contributions to American intelligence were groundbreaking but whose personal ambitions and lack of discretion ultimately led to his downfall. The book explores the tension between the need for secrecy in intelligence work and the public’s right to know, a theme that remains relevant in modern discussions about national security and government transparency.
The Reader of Gentlemen's Mail is not only a biography of Yardley but also a history of the early days of American cryptology, showing how the foundations of modern intelligence agencies were built on the work of pioneers like him. Kahn, a leading historian of cryptography, brings his expertise to the narrative, providing rich historical context and an in-depth analysis of Yardley’s techniques, successes, and failures. The book ultimately portrays Yardley as a man ahead of his time, whose legacy in codebreaking endured despite his contentious decisions and fall from grace.