From Sixteenth-Century Cryptography to the New Millennium — The Last 500 Years - Codes: The Guide to Secrecy from Ancient to Modern Times - page 82

In the spring of 1918, the Germans were planning a major offensive, presum-
ably to ensure the defeat of the Allies before the arrival of American troops.
The ADFGVX cipher turned out to be the toughest field cipher known up to
that time, and the Allies could not break the initial cryptograms. Then some
of those cryptograms were brought to the attention of the best cryptanalyst
in France's Bureau du Chiffre, Georges Jean Painvin (1886-1980) (see Figure
2.12). 2.6 The Bureau du Chiffre was considered to be one of the best black
chambers of the day, and Painvin was one of their top stars. The Allies needed
to know where the Germans were planning to make their major thrust in the
upcoming invasion. They needed Painvin to break the ADFGVX cipher.
Figure 2.12: Georges Painvin.
2.6 The photograph of Painvin is courtesy of the site owner who cited it as public domain at
http://www.annales.org/archives/x/painvinimages.html .