ADFGVX was in fact an extension of an earlier cipher called ADFGX which was first used on 1 March 1918 on the German Western Front.
Nebel designed the cipher to provide an army on the move with encryption that was more convenient than trench codes but was still secure.
ADFGVX was cryptanalysed by French Army Lieutenant Georges Painvin, and the cipher was broken in early June 1918.
His method of solution relied on finding messages with stereotyped beginnings, which would fractionate them and then form similar patterns in the positions in the ciphertext that had corresponded to column headings in the transposition table.
[3] Painvin broke the ADFGX cipher in April 1918, a few weeks after the Germans launched their Spring Offensive.
However, the claim that Painvin's breaking of the ADFGX cipher stopped the German spring offensive of 1918, while frequently made,[5] is disputed by some.
In his 2002 review of Sophie de Lastours' book on the subject, La France gagne la guerre des codes secrets 1914-1918, in the Journal of Intelligence History, (Journal of Intelligence History: volume 2, Number 2, Winter 2002) Hilmar-Detlef Brückner stated: Regrettably, Sophie de Lastours subscribes to the traditional French view that the solving of a German ADFGVX-telegram by Painvin at the beginning of June 1918 was decisive for the Allied victory in the First World War because it gave timely warning of a forthcoming German offensive meant to reach Paris and to inflict a critical defeat on the Allies.
Its aim had to be grossly exaggerated, which the German High Command did by spreading rumors that the attack was heading for Paris and beyond; the disinformation was effective and apparently still is.
However, the German offensive was not successful because the French had enough reserves at hand to stop the assault and so did not need to bring in additional reinforcements.
Moreover, it is usually overlooked that the basic version of the ADFGVX cipher had been created especially for the German Spring Offensive in 1918, meant to deal the Allies a devastating blow.
When Painvin presented his first solution of the code on 5 April, the German offensive had already petered out.The ADFGX and ADFGVX ciphers are now regarded as insecure.