In 1926, under a secret annex to the Treaty of Rapallo, the Soviet Union and Germany set up a joint tank school at Kazan, which was illegal under the Treaty of Versailles. Both countries learned much about tank design and tactics in this co-operative venture. The Germans provided advice on mechanisation of Soviet heavy industry, and helped develop a sense of professionalism in the Red Army. From 1929, an experimental Mechanised Brigade was formed, training and developing combined-arms tactics with foreign tanks, armoured cars, tractors, and lorries.