1929–1931: A Transition Period in U.S. Cryptologic History.

The years 1929 through 1931 were among the most turbulent in American cryptology. During this period, the joint War and State Department Cipher Bureau of Herbert Yardley was closed. The Army created the Signal Intelligence Service under William Friedman. Finally, the Army and Navy began their first tentative steps towards inter-service cooperation. This article examines these events in detail and also takes a look at the relationship between Yardley and Friedman. [ABSTRACT FROM PUBLISHER]