In 1922 U.S. Army cryptologist William F. Friedman published The Index of Coincidence and its Applications in Cryptography, Department of Ciphers. Publ 22. Geneva, Illinois, USA: Riverbank Laboratories.
Friedman's report presented the coincidence counting, or index of coincidence method of code-breaking.
This work appeared in 1922, and antedated the French translation noted below which was falsely dated 1921. Shulman, An Annotated Bibliography of Cryptography, 1976, pp 84-5 noted that the French translation was by General Cartier, and that both editions were printed in Paris by Col. Fabyan as anonymous publications.