with radios so that each tank commander could hear instructions from the unit commander allowing each tank to work with all others in an organized fashion. Soviet armour At the beginning of June, the Red Army included over 19,000 tanks in their inventory, most of them light tanks such as the T-26 or BT-7. The front armor of the T-26 was just 15mm thick, and the BT-7, just 22mm, offering virtually no protection against any anti-tank weapon at any range. Furthermore, the poor design of Soviet shells meant that most rounds shattered on contact, rather than penetrating. More modern tanks, such as the KV-1 and the T-34, were only beginning to roll off production lines and were not available in anywhere near the numbers that were needed to throw back the German advance. During the interwar years, farsighted military theorists such as Mikhail Tukhachevsky came to similar conclusions as Heinz Guderian regarding tanks in modern warfare. However, during the Great Purge Tukhachevsky was executed. Red Army tanks were dispersed widely throughout infantry divisions in the 1930s. Then came the shock of the Fall of France. Surviving armored warfare theorists such as Konstantin Rokossovsky were quickly and quietly reinstated in their positions and began assembling tanks into concentrated formations with all possible speed. However, by June 1941 this process was barely half complete, so many of the 19,000 tanks in the Red Army arsenal were still dispersed among infantry divisions on the eve of the invasion. This ensured that even if the Red Army had a unified command, many of its armored units would be committed piece-meal. German logistics At full strength, a German panzer division was a balanced formation with between 150 and 200 tanks, motorized infantry, motorized artillery, and motorized engineers. To support its logistical needs, each panzer division included 2000 trucks. Furthermore, each panzer division had its own integral artillery and infantry support, which meant that rather than providing a supporting role for infantry, German panzers performed a leading role, with infantry providing support. Furthermore, Wehrmacht doctrine stressed the importance of training soldiers in roles performed by other men. Tank crews were trained in artillery roles, infantry trained as tank crews, etc. Most importantly, tank crews were also trained as mechanics, giving them the knowledge to fix broken equipment in the field. Soviet logistics In the immediate pre-war period, few preparations were made, and the Red Army was