“Nazi Germany invaded the Soviet Union on June 22, 1941. Beginning on June 23 between Dubno, Lutsk and Brody in far western Ukraine, six Soviet mechanized corps under Gen. Mikhail Kirponos launched a counter attack into the advancing 1st Panzer Group advancing toward Kiev.” (yahoo.com)
“What’s all the more remarkable is that the Soviet corps had considerable numbers of heavier KV and T-34 tanks, tougher than the German army’s best tanks at the time. The Soviet 10th Tank Division of the 15th Mechanized Corps alone had 63 KVs and 38 T-34s” (medium)