The 'Battle of Kock' was fought between German and Polish forces within the context of 'Weiss' (i), and was the last battle of Germany’s conquest of western Poland (2/5 October 1939).

In this battle the Polish Independent Operational Group 'Polesie', commanded by Generał brygady Franciszek Kleeberg, fought the XIV Corps (mot.) commanded by General Gustav Anton von Wietersheim within Generaloberst Walter von Reichenau’s 10^th Army of Generaloberst Gerd von Rundstedt’s Heeresgruppe 'Süd'.

By this late stage of the 'Weiss' (i) campaign the Poles' overall battle plan had been wholly dislocated, in part by the lack of adequate numbers of effective officers. The Germans had destroyed the Polish reserves and forced the Polish forces into large-scale withdrawals to the east and south-east. Having taken heavy losses, the Polish armies fell back in the south to Kraków and in the centre to the Vistula river. From there, the central forces took the route from Warsaw to Sandomierz, and then from Sandomierz to the area of Lublin.

The western bank of the Vistula river had been held by weak forces centred on Lublin, and these forces were deployed only in areas where possessing east access to the points at which they could cross the Vistula river when the German attacked. The German forces advanced to the Vistula river and continued toward Zamość and Volodymyr-Volynskyi.

The Polish forces in the area of Kraków and Małopolska suffered heavy losses, and could not fall back to the line of the San river as had been planned. The Poles were thus unable to organise any form of effective defense. Marszałek Polski Edward Rydz-Śmigły, the Polish commander-in-chief, was now tasked with the defence of southern Poland, and Generał brygady Frantiszek Kleeberg, the commander of Army Area IX at Brześć, was responsible for the defense of the line between Pińsk and Brześć with the forces of his Independent Operational Group 'Polesie'.

On 8 September, Kleeberg was ordered by Rydz-Śmigły to organise a division of infantry from the depot division, in which reservists and recruits were trained. Kleeberg was also ordered to organise the defensive line between Brześć and Pińsk. While Kleeberg’s forces were well-trained, they lacked heavy weapons and much equipment as these had been despatched to bolster front-line divisions.

Kleeberg’s Independent Operational Group 'Polesie' was this a very mixed formation comprising Pułkownik Adam Epler’s 60^th Division 'Kobryń' (seven infantry battalions, one artillery unit and one anti-tank battery), Podpułkownik Kazimierz Gorzkowski’s 'Drohiczyn Poleski' Group (three infantry battalions and one anti-tank unit), the 'Jasiołda' Group (one infantry battalion, one machine-gun battalion, one anti-tank company and one unarmed labour battalion), the Brześć Fortress Group (three infantry battalions, one engineer battalion, two FT-17 light tank companies, two armoured trains and an artillery group), a river flotilla (several dozen small river motor boats, monitors and artillery craft) and eight batteries of anti-aircraft guns.

After breaking through the Polish line in the 'Battle of Wizna', General Heinz Guderian XIX Corps (mot.) started a rapid advance to the south. Comprising Generalleutnant Leo Freiherr Geyr von Schweppenburg’s 3^rd Panzerdivision, General der Panzertruppen Ferdinand Schaal’s 10^th Panzerdivision and Generalleutnant Mauritz von Wiktorin’s 20^th Division (mot.) with Generalleutnant Paul Bader’s 2^nd Division (mot.) in reserve, the corps was ordered to capture the old fortress in Brześć Litewski and then strike farther to the south toward Kowel and Galicia. The purpose of this attack was to cut Poland in two and paralyse the Polish defences to the east of the Bug river.

Initially, Guderian’s forces advanced almost unopposed. However, on 14 September, they were stopped in the area of Brześć Fortress and Kobryn by an improved force of four battalions under the command of General brygady Konstanty Plisowski. In a three-day battle which became known as the 'Battle of Brześć Litewski', each side suffered significant casualties. Although the Poles finally withdrew from the area on 17 September, the Germans did not start the pursuit soon enough to maul the retreating Poles. The simultaneous 'Battle of Kobryń' was inconclusive, with the Polish improvised Infantry Division 'Kobryń' under Epler withdrawing unopposed.

Both Polish forces from Kobryń and Brześć were soon joined by the 'Podlaska' Cavalry Brigade. This unit, commanded by General brygady Ludwik Kmicic-Skrzyński, successfully evaded encirclement by withdrawing through the Białowieża forest. Kmicic-Skrzyński and his chief-of-staff went to Vawkavysk, from which Kmicic-Skrzyński established telephone contact with Kleeberg. The two officers agreed to join their forces and move southward in the direction of the Romanian 'bridgehead' on the upper reaches of the Dniestr river.

Oberst Hans Kreysing’s 16^th Infanterieregiment (mot.), with artillery and Luftwaffe support, began an attack on the positions of the 83^rd Infantry Regiment on 18 September, capturing a number of Polish positions. The Polish counterattack, which began at 17.00, regained some territory, and Kleeberg began withdrawing his forces to Romania and Hungary. Over the next two days Polish forces were ordered to concentrate in he area to the north of Kowel. While on the march, a formation of the Independent Operational Group 'Polesie' was attacked by fifth columnists and from the air, but scattered bands of Polish soldiers joined the group.

After a battle with Soviet forces, Kleeberg decided on 22 September to march to the relief of Warsaw, starting with the seizure of crossing places on the Bug river. The concentration area was to be in the area of Włodawa. Polish units organised by Pułkownik Brzoza-Brzezina, fought only against the Germans as they had been ordered not to fight the Soviets unless they were themselves first attacked. Between 22 and 25 September, elements of the Independent Operational Group 'Polesie' were attacked by German aircraft during their march to Włodawa. On the last day of these attacks, Kleeberg received information that Włodawa had been recaptured by unknown Polish units, most of them comprising men from destroyed Polish formations who had not been caught by the Germans and were looking for commanders and formations which were still in the fight. Kleeberg’s staff began to organise the defence of a bridgehead in Włodawa.

Elsewhere, between 17 and 26 September, elements of the Independent Operational Group 'Polesie' crossed the Bug river and reached the area of Włodawa. After receiving information about the surrender of Warsaw, Kleeberg asked his subordinate commanders for their opinions after informing them of the political and military situation. He also asked Generał brygady Zygmunt Podhorski, commander of the Cavalry Division 'Zaza' (comprising the 'Pils' Cavalry Brigade, the 'Eduard' Cavalry Brigade, the 'Olek' Infantry Battalion, the 'Wilk' Infantry Battalion and the divisional artillery, to join him. Podhorski initially agreed, but then decided that he would first go to Stawy near Dęblin, the location of the Polish army’s main arsenal, before moving to the Holy Cross mountains and engaging in guerrilla warfare.

Kleeberg decided to reorganise his command. The Infantry Division 'Kobryń' was to received little in the way of resupply but would be renamed the 60^th Division under Epler’s command and with three infantry regiments, divisional artillery, one motorised company of 37-mm anti-tank guns, and a miscellany of smaller units. The 'Brzoza' and 'Drohiczyn' groups would be merged to create Brzoza-Brzezina’s 50^th Division with three infantry regiments and divisional artillery. In all, therefore, by this time Kleeberg had some 18,000 men.

On 28 September, the Polish forces began to march south to the Parczew-Wojcieszków line with the Cavalry Division 'Zaza' providing mobile defence. One of the Uhlan regiments of the 'Eduard' Cavalry Brigade crossed the Wieprz river and captured Spiczyn, and another cavalry regiment of the 'Zaza' Cavalry Division captured Jawidz and Wymysłów after some resistance. The Germans suffered heavy losses. The next day there was more fighting between the 'Zaza' Cavalry Division and the Germans near Spiczyn. That evening, the 60^th Division made contact with the Germans and entered a forest near Czeremniki. Deploying an infantry force supported by two tanks, the Germans attacked the 1/182^nd Regiment unsuccessfully.

By 30 September, the Polish forces were situated between the Tyśmienica and Wieprz river, and on the following day elements of the Independent Operational Group 'Polesie' passed the Świderki and the outlying hamlets of Bystrzyca, Wola Osowińska, Bełcząc and Ostrówek. The 'Zaza' Cavalry Division had halted in forests near the Tyśmianka river. One squadron of the 2^nd Uhlan Regiment, which was defending a road, destroyed a German reconnaissance patrol. The command element of 5^th Uhlan Regiment and the 'Olek' and 'Wilk' Infantry Battalions attacked the Germans in Kock and captured the town.

On 30 September, von Reichenau, commander of the 10^th Army, ordered his staff to plan the destruction of the large Polish force located between the Bug and Vistula rivers. This task would involve the XIV Corps (mot.), and comprised Generalleutnant Joachim Lemelsen’s 29^th Division (mot.), Generalleutnant Paul Otto’s 13^th Division (mot.) and several smaller units. Each of the motorised divisions had an establishment strength of 16,445 men, 2,676 trucks and staff cars, 1,944 motorcycles and 18 armoured cars.

von Wietersheim, commander of the XIV Corps (mot.), knew that Polish forces were located in the forests to the north-west of Kock, and believed that the Polish commander was ignorant of Warsaw’s capitulation.

Otto, commander of the 13^th Division (mot.), was of the opinion that the Polish forces had become so demoralised that they were incapable of effective combat, and that a single German battalion would be enough to disarm and take prisoner the Poles. Otto therefore despatched a force comprising only the 3/93^rd Infanterireregiment (mot.) supported by the 8^th Batterie of the 13^th Artillerieregiment. The battalion commander decided to divide his forces into two groups which were launched toward Serokomla and Kock. He could count on support from the 93^rd Infanterieregiment (mot.) and some smaller units.

At 08.30, a column of German half-tracked vehicles and truck-mounted infantry came under fire from a guard platoon of No. 2 Company of the 'Wilk' Infantry Battalion. After a protracted engagement the German troops withdrew. The 179^th Infantry Regiment was alerted and moved to defensive positions near and within Kock. At about 11.00 the leading German elements attacked the Polish positions, which were now held by two battalions. Despite supporting artillery fire, the German attack failed. At dusk, German motorcyclists appeared near the church in Kock and began firing, but subsequently withdrew when the fire was returned.

One company of German motorised infantry entered the village of Serokomla. This led to the beginning of a chaotic action between the Germans and Uhlans of the 'Pils' Cavalry Brigade. The Poles were supported by an artillery unit of the same brigade, and the Germans were forced to withdraw to the south of the village.

The German losses for the day were in the order of 300 to 400 men killed or wounded, and the Poles also took prisoner five officers and 180 other ranks. The committed units of the 'Pils' Cavalry Brigade lost about 200 men killed or wounded.

The stiff Polish resistance forced Otto to commit all his forces for an assault on 3 October. Otto’s plan was to divide the Polish forces into two groups for defeat in detail. Otto decided that Oberst Gustav Fehn’s 33^rd Infanterieregiment (mot.), supported by part of the divisional artillery, would attack Annopol, Pieńki and Talczyn and thus to destroy the 50^th Division. Oberst Dr. Ing. Karl Ritter von Weber’s 93^rd Infanterieregiment (mot.) was ordered to capture Serokomla and then Hordzież, and to destroy a defensive force of the 'Zaza' Cavalry Division. Oberst Traugott Herr’s 66^th Infanterieregiment (mot.) was committed to the battle during the afternoon.

Kleeberg believed that the Germans would commit their main strength against the 'Zaza' Cavalry Division in the area of Serokomla and Hordzież, and decided that only part of the cavalry would be adequate to fend off the German attack, while the rest of the division would join a counterattack alongside the 50^th Division on the right wing and rear of the 13^th Division (mot.). The 60^th Division and the 'Podlaska' Cavalry Brigade would close off potential German attack routes. If this counterattack was successful, the German division would be forced to withdraw behind the Wieprz river.

Between 07.50 and 09.30, two regiments the 180^th and 178^th, the latter less its 2^nd Battalion) of the 50^th Division attacked with support from a howitzer battery. The attack was commanded by Gorzkowski. Initially successful, the Polish units were brought to a halt and then forced onto the defensive. The cavalry attack by the Uhlans was also stopped and forced to withdraw to the west of Wola Gułowska.

At 10.30, German artillery began to fire on the Polish cavalry positions and the 93^rd Infanterieregiment (mot.) began an attack on the 'Wilk' Battalion’s positions, inflicting heavy losses. The 33^rd Infanterieregiment (mot.) began a creeping attack on the Polish 50^th Division.

After heavy fighting, the German advance was stopped. Otto next decided to support the 33^rd Infanterieregiment (mot.) with the 2/66^th Infanterieregiment (mot.). German units now captured Wola Gułowska but, during the evening, were forced to withdraw from the eastern part of the area and go onto the defensive in the western part.

On 4 October, following the failure of the 13^th Division (mot.), von Wietersheim was forced to commit the 29^th Division (mot.). Otto ordered the 93^rd Infanterieregiment (mot.) to move from the Wieprz river to Dęblin. The 66^th Infanterieregiment (mot.) was to attack Adamów and Wola Gułowska, and the 33^rd Infanterieregiment (mot.) was to clear the area to the north of Kock.

Kleeberg suspected that the main attack of the 13^th Division (mot.) and the 29^th Division (mot.) would fall on Adamów and Krzywda, and believed that there was an opportunity to destroy the 13^th Division (mot.) as this had already sustained heavy losses in men and matériel. The 'Zaza' Cavalry Division and the 50^th Division were therefore to defend their positions while the 60^th Division attacked the 13^th Division (mot.). The 'Podlaska' Cavalry Brigade was to oppose the 29^th Division (mot.).

In the morning, the main elements of 13^th Division (mot.) attacked the 'Zaza' Cavalry Division and the 50^th Division. By 12.00 part of the 66^th Infanterieregiment (mot.) had captured Zakępie and advanced on Adamów, where it were halted by the 1/180^th Regiment.

About 11 hours apart, first from the west and then the east, elements of the 66^th Infanterieregiment (mot.) attacked the 'Olek' and 'Wilk' Battalions defending Czarna. The defenders sustained heavy casualties from artillery fire and the 'Wilk' Battalion was compelled to withdraw to the eastern edge of the Adamów forest. The 'Olek' Battalion, moving to Adamów, later deployed to Gułów. Between 10.00 and 11.00 elements of the 66^th Infanterieregiment (mot.) attacked units of the 5^th Uhlan Regiment, which then withdrew from Wola Gułowska and Adamów to the south-east.

At about 12.00 the 66^th Infanterieregiment (mot.) attacked the 2^nd Squadron of the 2^nd Uhlan Regiment in Zarzecze, and the squadron had no option but to withdraw with heavy casualties. The regimental commander moved the 4^th Squadron to the south from Helenów in an effort to aid the 2^nd Squadron while the 3^rd Squadron held the Germans to the west of Wola Gułowska. The 3^rd and 4^th Squadrons, together with elements of the 10^th Uhlan Regiment, fought near Turzystwo village cemetery and the church in Wola Gułowska. Ground was lost and retaken repeatedly until an attack by the 2/184^th Regiment and the Uhlan squadron enabled the Polish to dig in.

On 5 October, von Wietersheim decided that he would use two of his divisions, which were to attempt an encirclement and destroy the Polish forces. The 13^th Division (mor.) was to advance on Bystrzyca and Adamów and then on Nowa Wróblina and Stanin; and the 29^th Division (mot.) was to advance on Radoryż Kościelny and Nowa Wróblina, where it was to link with the 13^th Division (mot.).

Kleeberg decided to destroy the 13^th Division (mot.) using forces of the 50^th and 60^th Divisions and the 'Zaza' Cavalry Division. The 'Podlaska' Cavalry Brigade defended the position under Radoryż Kościelny and Nowa Wróblina.

The 13^th Division (mot.)'s artillery began to fire on the 180^th Regiment battalion’s positions in Adamów and the 'Olek' Battalion in Gułów at 05.30. Some 150 minutes later, the 66^th Infanterieregiment (mot.)'s advance began. After a short fight at 10.00, the Germans captured Adamów, and then attacked the Polish position on Hill 170 and Gułów, which they captured after heavy fighting. In this fighting the 66^th Infanterieregiment (mot.) sustained substantial losses. The Polish division occupied positions on the eastern edge of the Adamów forest. Podhorski sent the 'Pils' Cavalry Brigade to provide support, After contact with the German forces, the brigade began an attack on the German positions in the forest. The Poiles took the forest area and established defensive positions in it.

After the 66^th Infanterieregment (mot.)'s capture of Adamów and Gułów, the 33^rd Infanterieregiment (mot.) began to advance, capturing Wojcieszków and Glinne. The 178^th Regiment withdrew. The commander ordered his men to retake Wojcieszków and Glinne, which they did, but they then withdrew after taking heavy losses. The advance of the 180^th Regiment on Adamów failed. Brzoza-Brzezina committed the 178^th Regiment, which soon met the German advance. The 1^st Battalion included part of an engineer company, and the 2^nd and 3^rd Battalions took heavy losses and withdrew to Burzec.

Meanwhile, an attack by the 184^th Regiment, with the support of a battalion of the 179^th Regiment, recaptured the church and cemetery in Wola Gułowska. An advance by the 182^nd Regiment with the help of three 100-mm (3.94-in) howitzers broke the German defense in Helenów.

At 16.00, the final German advance from Adamów began on positions of the 10^th Uhlan Regiment in the Krzywda forest, the 182^nd Regiment in Helenów and the 184^th Regiment in Wola Gułowska. The 10^th Uhlan Regiment, after a hard fight, withdrew into the forest. Most forces of the 'Brzoza' Division successfully defended its positions in Burzec. The 182^nd Regiment also held its position, but the 184^th Regiment had to withdraw after all the artillery ammunition had been expended. During this time two key Polish advances began. The 2/183^rd Regiment, with artillery support, began a bayonet assault on the Germans who had attacked the southern wing of the 'Pils' Cavalry Brigade. The assault succeeded and the Germans began to retreat, being chased by infantry and cavalry. The rear of the southern wing of the 13^th Division (mot.) was attacked by the 'Eduard' Cavalry Brigade, which took the village of Poznań, including a German artillery battery though this had to be destroyed when the cavalry were forced to withdraw as it came under the fire of another German artillery battery. Elements of the 13^th Division (mot.) began to withdraw. One of the last attacks was delivered by the 29^th Division (mot.) on the 'Podlaska' Cavalry Brigade’s positions and on the rear of the 'Brzoza' Division. Both of these Polish forces were then withdrew to the south of Krzywda.

At 16.30, Kleeberg gave his last order in Hordzieżka, and then, as the Hordzieżka forest was being shelled, returned to his headquarters in Krzywda. At 20.40, Podpułkownik Kazimierz Gorzkowski and Podpułkownik Tadeusz Śmigielski left to establish contact with the headquarters of the 13^th Division (mot.), finding this near Adamów, and both sides agreed to a ceasefire lasting until 06.00 on the following day, before which a surrender was to be concluded.

The Independent Operational Group 'Polesie' surrendered at 10.00 on 6 October. In his last order, Kleeberg wrote that the reason for his decision to capitulate was that the Polish forces were surrounded and ammunition and food supplies were very low. Kleeberg’s surrender took place on 6 October at the Jabłonowskich Palace in Kock.