On the southern side of the bulge produced by Panzergruppe 1’s advance, Karpezo’s 15th Mechanized Corps was joined by General-leytenant Dmitri I. Ryabyshev’s 8th Mechanized Corps, which had just completed a 600km road march to the front. Ryabyshev’s corps had lost almost half its tanks due to mechanical breakdown, including forty-four out of forty-eight T-35 heavy tanks. Ryabyshev’s corps conducted a forward passage of lines early on 26 June, passing through Karpezo’s disorganized corps. Karpezo opted to remain on the defensive, allowing Ryabyshev to make the main effort in assaulting the right flank of General der Panzertruppen Werner Kempf’s XXXXVIII Armeekorps (mot.) between Leshnev and Kozyn. Ryabyshev began a premature attack with General-major Timofei A. Mishanin’s 12th Tank Division at 0900 hours, but the rest of his corps could not be committed until the afternoon. Ryabyshev intended to capture the village of Leshnev, then push on to seize Berestichko, which would isolate the 11.Panzer-Division at Dubno. Ryabyshev was confident that Mishanin’s division, which had a company of KV-1 tanks and a full battalion of T-34 tanks, could accomplish this mission.
Unfortunately, Mishanin’s armour was committed nearly straight off the line of march, with no time to reconnoitre the unfamiliar terrain or for his artillery and engineers to arrive. Consequently, Mishanin conducted a nearly pure-armour attack with his two tank regiments, but only minimal infantry support. The tanks immediately encountered very marshy terrain along the Syten’ka River, which was little more than a stream, but the Soviet tank crews lacked the skill to negotiate even this minor obstacle. Three T-34 tanks were stuck in the marshy terrain and Mishanin was forced to look for an alternate crossing in full sight of the German troops from the 57.Infanterie-Division in Lishnev. As the Soviet tanks bunched up around the river, the Germans called for artillery fire, which pounded the massed armour. Eventually, Mishanin was able to get his tanks across the marshy terrain and assault into Leshnev. The German panzerjäger were overwhelmed by the T-34 and KV-1 tanks and a number of Pak guns were crushed under their tracks. The German infantry abandoned Leshnev and fell back. However, before Mishanin could consolidate on the objective, an armoured kampfgruppe from Hube’s 16.Panzer-Division attempted to retake Leshnev. While the Pz.III and Pz.IV tanks were seriously out-gunned by the T-34 and KV-1 tanks, the German panzers enjoyed artillery and air support, as well as better C2, which evened the odds considerably. German gunners concentrated on hitting the tracks on the bigger Soviet tanks and succeeded in immobilizing some of the T-34s. Eventually, the German panzers broke off the action and retreated. Mishanin had twenty-five tanks stuck in the marshes or knocked out around Leshnev and was in no position to continue the attack with his unsupported armour. Instead, he sent a company of KV-1 tanks forward to sever the Berestichko-Dublin road and to shoot up some of the German wheeled traffic along this route. Ryabyshev’s other two divisions, the 34th Tank and 7th Mechanized, only got into the fight late in the day and achieved little or nothing.
Amazingly, one of the most powerful Soviet armoured units of June 1941 had failed to inflict significant damage on a single German infantry division. The Red Army’s failure to use combined arms tactics – which was mostly due to impatience in the higher command – almost completely negated the superior capabilities of the T-34 and KV tanks. By the end of 26 June, it appeared that Ryabyshev and Karpezo were still in an excellent position to smash in von Kleist’s right flank on the next day, but the Germans had their own surprise in store. German reconnaissance aircraft had been observing the mass of Soviet armour around Brody all day and they had spotted the GAZ-AAA radio trucks belonging to both the 8th and 15th Mechanized Corps command posts. Around 1800 hours, several groups of low-flying Ju-88 bombers from Fliegerkorps V came in and bombed both command posts. Karpezo was badly wounded but Ryabyshev survived, minus his radio truck, which was left burning. This one air strike – which was a result of poor operational security in the Red Army – seriously degraded Soviet C2 in the armoured battles around Dubno. On top of these difficulties, the Stavka reiterated its order at 2100 hours that Kirponos would continue attacking with all armoured forces and forbid even tactical retreats to prevent encirclements.
Despite Kirponos’ intent to launch a pincer attack from Rovno and Brody to encircle the German forces in Dubno, the lack of coordination between the mechanized corps and other Red Army units resulted in a series of piecemeal battles throughout 27 June. The pincer from Rovno collapsed as Feklenko’s and Rokossovsky’s understrength corps dashed themselves to pieces against 14.Panzer-Division and two supporting infantry divisions. Von Kleist’s panzers now had the benefit of infantry support, which had caught up with them, greatly increasing the staying power of the frontline units. Once the Soviet armour from the 9th and 19th Mechanized Corps was spent, the Germans committed their armour: both 13 and 14.Panzer-Divisionen attacked, threatening to envelop the remnants of Feklenko’s and Rokossovsky’s corps. Meanwhile, Crüwell’s 11.Panzer-Division blasted its way through a thin blocking force of Soviet infantry and captured Ostrog. A counterattack by fifteen BT-7 light tanks against Panzer-Regiment 15 in Ostrog failed to budge the Germans. Kirponos was forced to cobble together Task Force Kukin, a small mechanized formation, to block Crüwell from pushing even further east.
In spite of the myriad problems afflicting the Red Army’s armour units at the outset of the war, Ryabyshev’s 8th Mechanized Corps came close to achieving a real success southwest of Dubno on 27 June. Assembling Mishanin’s 12th Tank Division, Polkovnik Ivan V. Vasil’ev’s 34th Tank Division and Colonel Aleksandr G. Gerasimov’s 7th Motorized Division north of Brody, Ryabyshev was able to mount a fairly organized attack that managed to envelop and isolate the 11 and 16.Panzer-Divisionen, as well as part of the 75.Infanterie-Division, by midday on 27 June. A number of Soviet tanks were lost crossing the marshy terrain, but a mobile group with about 200 tanks succeeded in fighting its way to the outskirts of Dubno. Mishanin was wounded in the attack and Soviet losses were heavy, but the situation for Kempf’s XXXXVIII Armeekorps (mot.) was equally desperate. By the end of the day, German and Soviet armour units were thoroughly intermixed southwest of Dubno and there was no distinct front line.
Although Zhukov abruptly returned to Moscow, he continued to hound Kirponos by teletype messages to continue the counter-offensive against von Kleist’s Panzergruppe 1. Kirponos, intimidated by his commissars, complied and thereby sentenced much of the remainder of his armour to annihilation. Rokossovsky managed to scrape together a battle group with about fifty T-26 and BT light tanks, a handful of KV-2 heavy tanks and some infantry, which he used to attack into the northern flank of Panzergruppe 1’s bulge on the morning of 28 June. However, by this point the infantry from 6.Armee had arrived in force to bolster von Kleist’s exposed flanks and the panzerjägers from 299.Infanterie-Division stopped Rokossovsky’s attack cold. Polkovnik Mikhail E. Katukov led his thirty-three BT-2 and BT-5 light tanks into battle and lost all of them. As usual, Soviet armoured attacks went in with little or no reconnaissance support and negligible artillery support. Massed artillery, anti-tank fire and flak destroyed most of the Soviet armour, although a single damaged KV-2 limped away. Once the Soviet attack was spent, Generaloberst von Mackensen deftly coordinated the 13 and 14.Panzer-Divisionen into an all-out attack that smashed in the flanks of the Soviet 9th and 19th Mechanized Corps. The fragments of seven Soviet tank and motorized infantry divisions were routed and fled back behind the Goryn River. Feklenko abandoned Rovno, which was quickly occupied by the 13.Panzer-Division.
While disaster was striking the northern group of Soviet armour, Ryabyshev’s 8th Mechanized Corps found itself being encircled. This was the first instance in the war in the East of Soviet armour achieving a significant penetration of German lines, and Ryabyshev set a precedent that would occur again and again over the next two years. First, no follow-on forces were available to support the breakthrough; the nearly leaderless 15th Mechanized Corps mounted only a demonstration attack against the infantry of the German XXXXIV Armeekorps which provided no help to Ryabyshev. Second, the Germans reacted quickly to sever the narrow penetration corridor used by the attacking Soviet armour, isolating the bulk of the 12th and 34th Tank Divisions in a kessel just west of Dubno. Third, morale and C2 within the trapped forces quickly disintegrated, resulting in rapid loss of any unit cohesion. The German 75.Infanterie-Division played a vital role in isolating the bulk of Ryabyshev’s forces, which speaks volumes about the Soviet lack of battlefield situational awareness at this point. A foot-marching infantry unit could envelope fully motorized units. Once Ryabyshev’s armour was encircled, Hube’s 16.Panzer-Division began a series of attacks that quickly reduced the kessel. German heavy artillery and flak was brought up to finish off the trapped Soviet T-34 and KV-1 tanks, which were now low on fuel and ammunition; twenty-two tanks were knocked out. Ryabyshev, who was outside the kessel, personally led the 7th Motorized Infantry Division in an effort to break through to his two trapped tank divisions, but failed after crippling losses. By the end of 28 June, Ryabyshev’s corps had been neutralized and von Kleist’s Panzergruppe 1 had driven a deep wedge into the boundary of the Soviet 5th and 6th Armies. In just six days of battle, four of Kirponos’ mechanized corps had been defeated and the remainder had been seriously reduced.
For the first six days of the battle, while Kirponos was grinding up his own armoured forces in piecemeal battles, von Kleist held back the 9.Panzer-Division and his four motorized divisions. Once the best Soviet armoured formations were spent, von Kleist began to commit his second-echelon motorized forces on 28–29 June. The 9.Panzer-Division attacked unexpectedly into the flank of the Soviet 6th Army north of L’vov and quickly broke through its infantry. The 16 and 25.Infanterie-Division (mot.) used their superior mobility to quickly reinforce the flanks of Panzergruppe 1 at Berestichko and Rovno, which enabled the panzer divisions to resume their attacks eastward. Von Mackensen’s III Armeekorps (mot.) sliced into the fragments of Rokossovsky’s forces and pushed them back. After heavy fighting with Hube’s 16.Panzer-Division southwest of Dubno, Ryabyshev retreated with the remnants of his corps, reduced to 35 per cent of their initial tank strength, four infantry battalions and four batteries of artillery. The rest of his corps, roughly 10,000 troops and 200 tanks, were left in the kessel outside Dubno. With the Southwest Front’s forces in retreat or faced with encirclement, the Stavka finally ordered Kirponos to withdraw to the Stalin Line on the old border.
In the final actions near Dubno, the trapped tankers of the 34th Tank Division took advantage of fog along the Ik’va to stage a breakout operation on the night of 30 June, which succeeded in saving some troops, but not much equipment. In a confused night action – rare on the Eastern Front – the Soviets massed their remaining tanks and punched through Hube’s cordon. The Germans massed artillery, flak guns and tanks to destroy the fleeing Soviets, but some German troops panicked when T-34 and KV heavy tanks appeared out of the mist and overran their positions. Corps Commissar Nikolai Popel, leading the breakout, later wrote:
One of our T-34s flared up like a torch, darting around a field. Over a dozen Pz.IVs ganged up at the same time on a KV-1. We were shooting German vehicles pointblank. When ammunition ran out, we rammed them … Sytnik’s KV-1 [Major A. P. Sytnik, commander 67th Tank Regiment], in the heat of battle, rushed ahead of the others. [He] rammed several Pz.IIIs. His vehicle became a pile of shapeless metal. He began retreating with his crew deeper into the thickets.
By 1 July, the Southwest Front was in full retreat and Panzergruppe 1 had achieved its initial objectives. The tank battles fought between Panzergruppe 1 and elements of seven Soviet mechanized corps around Lutsk-Rovno-Dubno-Brody in the first week of Barbarossa were the largest tank battles to date, involving over 600 German and 3,800 Soviet tanks. While it is true that von Kleist failed to encircle and destroy any Soviet mechanized corps, as occurred in the battle of the Bialystok-Minsk kessel, the 8th, 15th and 19th Mechanized Corps were badly mauled and three other mechanized corps lost at least half their strength. Approximately two-thirds of the Soviet armour, or 2,500 tanks, were lost in the battle between 22–30 June 1941; the majority of losses were caused by non-combat factors, including mechanical failure and lack of driver training. The technical superiority of the Soviet KV-1 and T-34 tanks counted for very little in the Battle of Dubno due to untrained crews and inept tactics. The Stavka’s insistence on launching a premature counteroffensive resulted in the best Red Army armoured units being thrown into battle piecemeal, where they were chopped to ribbons by veteran panzer units. In addition to material losses, losses of senior armoured leaders included two of six mechanized corps commanders, six of eighteen division commanders and ten of thirty tank regiment commanders. The surviving formations were reduced to division-size battle groups with little artillery or support services left after the retreat to the Stalin Line. The one bright spot for the Red Army in the Ukraine was that second-echelon armoured units near Kiev and the 2nd and 18th Mechanized Corps, deployed with the Southern Front near Odessa, were too distant to be significantly affected by the initial German Blitzkrieg; these formations would greatly assist Kirponos in slowing Heeresgruppe Süd’s advance upon Kiev in July–August.
In contrast to the damage suffered by Kirponos’ first-echelon armour, the German panzer units in Panzergruppe 1 suffered very light losses in the first week of combat; no senior panzer leaders were casualties and total personnel losses were around 5 per cent or less. Excluding Pz.I and command tanks, no more than twenty-five tanks in Panzergruppe 1 were totally destroyed by 30 June, with about another 100 damaged or down for mechanical defects, but all five panzerdivisions were still fully combat-capable. German leadership, from von Kleist, to von Mackensen and Kempf at corps level, to Crüwell and Hube at division level, had demonstrated great flexibility and aggressiveness. Even when briefly isolated, the panzer divisions retained their cohesiveness and fought their way out of trouble. To be sure, the Pz.III tanks armed with the 3.7cm KwK 36 L/46 cannon had proven to be a liability in combat against Soviet tanks, but the German skill at combined arms warfare and air-ground coordination had carried the day against Soviet numerical superiority and technical advantages. As Heeresgruppe Süd continued its advance to the Stalin Line in early July 1941, von Kleist was still outnumbered but his forces were better handled and, thus, capable of achieving decisive local superiorities.