On 23 June General Kirponos, Commander of the Southwestern Front, ordered the 8th Mechanized Corps, part of 26th Army at the time, to move to Brody out of Kostenko's command. Afterwards, the formation operated assigned to the N. I. Muzychenko's 6th Army. During the road march from its initial positions in the Drogobychskaja sector in the Ukraine to the Brody area, the corps lost about half its older tanks to mechanical breakdown and enemy air attack. It then became embroiled in the Battle of Brody (1941). On 25 June 1941, 12th and 34th Tank Divisions were clearing the hills south of Brody before the whole corps opened its attack later that day. "...Its 34th Tank Division and elements of the 12th Tank Division advanced northwards, cutting the main road between Dubno and Brody. This forced the 16th Panzer Division to wheel round and attack the 34th Tank Division in the area of Kozin, in order to clear the road."