During the 1920s Herbert O. Yardley was chief of the first peacetime cryptographic organisation in the United States, the ancestor of today’s National Security Agency. Funded by the US Army and the Department of State, Yardley’s small and highly secret unit based in New York succeeded in breaking the diplomatic codes of several nations, including Japan. Despite its extraordinary success, the Black Chamber, as it became known, was disbanded in 1929. President Hoover’s new Secretary of State, Henry L. Stimson, refused to continue its funding with the now famous comment,`Gentlemen, do not read other people’s mail.’ In 1931 a disappointed Yardley caused a sensation when he published this book and revealed to the world exactly what his agency had done with the secret and illegal cooperation of nearly the entire American cable industry. These revelations and Yardley’s right to publish them set in motion a conflict that continues to this day: the right to freedom of expression versus national security.