After the First World War the German Army was in crisis. Limited in the size and its equipment by the Versailles Treaty which ended the war, it was a shadow of the mighty force it had been in 1914. Help came from a surprising source. Soviet Russia.

Historian Ian Johnson explains to Dan how it was the Soviets who helped rebuild the German military machine before World War Two.

30% of Weimar Germany's defence spending took place in the USSR. 25% of German officers passed through camps in Soviet soil. This is the shocking conclusion reached by Ian Johnson who has trawled through the archives to understand just how much the German war machine owed to Soviet support. The cash strapped communists were happy to take German money in return for training areas, tank development labs and other activities banned by the Versailles Treaty.

The Soviets helped turn the Wehrmacht into a military machine that in 1941-2 came very close to toppling the Soviet state.