Page "Blitzkrieg" Paragraph 22

The Reichswehr and the Red Army collaborated in war games and tests in Kazan and Lipetsk beginning in 1926.

Set within the Soviet Union, these two centers were used to field test aircraft and armoured vehicles up to the battalion level, as well as housing aerial and armoured warfare schools through which officers were rotated.

This was done in the Soviet Union, in secret, to evade the Treaty of Versailles's occupational agent, the Inter-Allied Commission.