The remaining 763 machines were obsolete models averaging barely 500 kilometres (310 mi) between maintenance checks, and 197 of them were in need of a full factory overhaul.

During the 500 kilometres (310 mi) road march from its initial positions in the Drogobychskaja sector in Ukraine to the Brody area, the corps lost about half its older tanks to mechanical breakdown and enemy air attack.

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.

Thus much of the unengaged remnants of 34th Tank Division were formed into an about 9,000-strong strike group led by Brigade Commissar Popel of corps headquarters, whose attack saw some initial success.

Later however the strike group was encircled and after losing all heavy equipment after almost one month of fighting, group, around 1800 strong under command of Brigade Commissar Popel, successfully reach soviet lines and connected with remains of 8th Mechanized Corps under general Ryabyshev .