Three Soviet formations deployed a potent force of modern T-34 and
KV tanks: the 4th, 8th, and 15th Mechanized Corps. The 717 such tanks comprised almost a half of the country's 1,600 production of these two models. Throughout the battles, the scale of the intended operations and the precise role of each corps in the plan were communicated poorly or not at all. Ryabyshev noted that "the Corps battle orders spoke only to its own mission objectives". There was little to no communication between the individual corps to ensure co-ordination.
10th Tank Division The Soviet 10th Tank Division was subordinate to 15th Mechanized Corps. On 22 June 1941, the forward battalions captured Radekhiv from the German infantry, losing two tanks. The next day it faced the German 11th Panzer Division there, destroying 20 German tanks and losing 6 T-34 tanks and 20 BT tanks. It withdrew in an orderly fashion because of a lack of ammunition. On 26 June 1941, the division destroyed 23 German tanks and an infantry battalion near Radekhiv, losing 13 KV and 12 BT-7 tanks.
15th Mechanized Corps Commanded by I. I. Karpezo. The 15th Mechanized Corps as a whole had 749 tanks, including 136 T-34 and KV tanks. Due to a series of inconsistent orders, the Corps spent the battle moving chaotically in the Radekhiv–Brody–
Busk triangle. Except for the two engagements with the 10th Tank Division, its forces were not in combat. On 7 July 1941 it reported in
Berezovka ( from the former border) with nine per cent of its tanks.
22nd Mechanized Corps Commanded by Major-General S. M. Kondrusev. On 24 June the 22nd Mechanized Corps attacked towards . On 29 June it reported having only 19 per cent of its former number of tanks. On 1 July one regiment unsuccessfully attacked toward Dubno. On 15 July 1941 the 22nd MC had 4 per cent its tanks remaining. Major General Semyon Kondrusev was killed by a shell during fighting near the village of Aleksandrovska in the
Volyn region on June 24, 1941.
41st Tank Division, 22nd Mechanized Corps Thirty-one of this unit's KV tanks, its most effective fighting element, blundered into swampy terrain and were lost.
19th Mechanized Corps Commanded by Major General
Nikolay Feklenko. On 26 June it attacked towards Dubno from the north, but failed to reach it by a few kilometers. On 29 June the corps had 32 tanks remaining out of the original 453.
8th Mechanized Corps Ryabyshev's 8th Mechanized Corps finally arrived on the scene on the 25th. On 26 June 1941, the 8th Mechanized Corps as a whole successfully attacked in the direction of Brody–
Berestechko against parts of the German 11th Panzer Division. Despite haphazard arrangements and difficulties, the Soviet attack met with some initial success, catching the Germans on the move and outside their prepared positions, their tanks sweeping aside hastily arranged German anti-tank positions manned by motorcycle troops attached to the
48th Panzer Corps. Later the 8th MC split, with some amalgamating into
Nikolai Popel's group and a second force remaining under the command of Ryabyshev.
12th Tank Division Fifty-six KV and 100 T-34 tanks of this division ran out of fuel and ammunition while attacking near Dubno. Combat operations were forced to a standstill.
Popel's group tank Popel's group had about 300 tanks, including no less than 100 T-34 and KV tanks. On 27 June, Popel's group surprised and defeated the rear of 11th Panzer Division and captured Dubno, a road crossing of strategic importance. This was the most successful Soviet action of the battle, as it cut off supply lines of the German armoured spearhead (the 11th Panzer Division). However, this was not exploited by Soviet command, who failed to communicate with Popel and to provide supplies or reinforcements. The group waited in Dubno and prepared for defence, losing the operational initiative. The situation was considered "serious" by the German high command: By 28 June the Germans had gathered enormous forces. Popel's group came under attack by elements of the
16th Motorized,
75th Infantry Division, two other infantry divisions, and the
16th Panzer Division. Encircled in Dubno, Popel defended until 1 July, when he retreated.
Ryabyshev's group Ryabyshev's group had 303 tanks, including 49 T-34 and 46 KV. On 28 June, in an attempt to follow Popel, it met and attacked the German 57th Infantry and 75th Infantry Divisions, as well as elements of 16th Panzer Division. The attack was unsuccessful and the Soviets quickly retreated. On 1 July Ryabyshev reported in
Tarnopol with 207 tanks, including 31 T-34 and 43 KV tanks. With no further combat, the 8th MC moved to
Koziatyn, where on 7 July 1941 it had 43 tanks – 5 per cent of the pre-war number.
4th Mechanized Corps The 4th Mechanized Corps commanded by
Andrei Vlasov was the strongest in the Ukraine, having 313 T-34 and 101 KV among its total of 979 tanks. It reacted slowly to orders and failed to assemble for attack. The most it achieved was on 28 June, when it secured the retreat of 15th Mechanized Corps from the pushing German infantry. Whilst not attacking or being attacked, the corps reported it retained no more than 6 per cent of its KV tanks, 12 per cent of its T-34 tanks, and 4 per cent of its light tanks on 12 July. Besides these, there were no more notable Soviet counter-attacks in this battle. ==Decision, indecision, and confusion of command: the historical debate==