Battle of the Bzura

The battle can be divided into three phases:


Modlin (16–19 September)^[1]


On the night of 9 September, the Polish Poznań Army commenced a counterattack from the south of the Bzura river, its target being the German forces from the 8th Army advancing between Łęczyca and Łowicz towards Stryków.^[13][14] The commander of Poznań Army, Tadeusz Kutrzeba noticed that the German 8th Army, which was commanded by General Johannes Blaskowitz, was weakly secured from the north by only the 30th Infantry Division, which stretched over a 30 km defensive line while the rest of the army was advancing towards Warsaw. The main thrust of the Polish offensive were the units under General Edmund Knoll-Kownacki, which were known as the Knoll-Kownacki Operational Group (Polish 14th, 17th, 25th and 26th Infantry Divisions).^[13][14][15] The right wing of the offensive, in the area Łęczyce, included the Podolska Cavalry Brigade under Col. L. Strzelecki, and on the left, advancing from Łowicz to the area of Głowno, the Wielkopolska Cavalry Brigade under General Roman Abraham.^[13][14][16] These groups inflicted considerable losses on the German defenders from the 30th Infantry Division and the 24th Infantry Division, with some 1,500 German soldiers killed or wounded and an additional 3,000 lost as prisoners during the initial push.^[13][14][17] The cavalry brigades, supplemented with TKS and TK-3 reconnaissance tanks, moved to threaten the flanks and the rear of the advancing German units.^[18]


The German forces were thrown back approximately 20 km, and the Poles recaptured several towns, including Łęczyca and Piątek, and the village of Góra Świętej Małgorzaty.^[13] On 10 September, the Polish 17th Infantry Division met the German 17th Infantry Division at Małachowicze. The following day, Polish forces continued their attack and advanced on Modlna, Pludwiny, Osse and Głowno.^[13]


Initially underestimating the Polish advance, the Germans decided on 11 September to redirect the main force of the German 10th Army, the German 4th Army, the reserves of the Army Group South and aircraft from 4th Air Fleet towards the Bzura. The forces included the German 1st Panzer Division, German 4th Panzer Division and the newly-formed SS Infantry regiment Leibstandarte Adolf Hitler.^[19] German air superiority had a significant impact by making it very costly and difficult for the Poles to move units during the day.^[14] The following day, the Poles reached the line Stryków-Ozorków. That day, General Tadeusz Kutrzeba learned that units of Army Łódź had retreated to the Modlin Fortress and decided to stop the offensive and instead sought to try to break through Sochaczew and the Kampinos Forest to reach Warsaw.^[14][19]


On the morning of 14 September, General Władysław Bortnowski's 26th and 16th Infantry Divisions crossed the Bzura near Łowicz. The Polish 4th Infantry Division reached the road linking Łowicz with Głowno. At that point, however, Bortnowski ordered the 26th Infantry Division to retreat. He had learned of the withdrawal of the German 4th Panzer Division from the outskirts of Warsaw and was concerned that the Panzer division posed a threat to his men.^[19]


On 15 and 16 September, Army Pomorze took up defensive positions on the north bank of the Bzura. General Stanisław Grzmot-Skotnicki's group between Kutno and Żychlin, General Michał Karaszewicz-Tokarzewski's units near Gąbin and parts of Army Poznań by the Bzura near Sochaczew were ready to begin their drive towards Warsaw. To encircle and to destroy the Polish forces, the Germans used most of their 10th Army, including two armoured, one motorized and three light divisions, which was equipped with some 800 tanks altogether. The attack from all sides on Polish positions started on 16 September with the support of the Luftwaffe. On 15 September, the Poles were forced out of Sochaczew, a town on the Bzura river, and were trapped in a triangle of Bzura, Vistula and German forces.^[14][20] The German 1st Panzer Division, after crossing the Bzura between Sochaczew and Brochów and engaging the Polish 25th Infantry Division, managed to capture Ruszki, but its advance was then halted. Poles began to cross the Bzura near the Vistula, north of Sochaczew, and retreat towards Warsaw.^[14][20][21]


The Polish forces were forced to abandon most of their heavy equipment while they crossed the river.^[20] On 17 September, German heavy artillery was shelling the crossing north of Brochów, and the largest air operation of the campaign began, with the Luftwaffe attacking the retreating Polish forces.^[14][20]


During the night of 17 September, the main forces of Army Poznań attacked the German forces to break out of the German encirclement between Witkowice and Sochaczew. The 15th Infantry Division and Podolska Cavalry Brigade again crossed the Bzura in Witkowice. In Brochow, the 25th and the 17th Infantry Divisions crossed the Bzura. The 14th Infantry Division was concentrated in Łaziska. At the same time, Army Pomorze marched towards the villages of Osmolin, Kierozia and Osiek.


In the morning, the Germans started their drive towards the south along both banks of the Bzura and were supported by more than 300 aircraft and heavy artillery.^[20] German howitzers, taking advantage of their position on the high ground of the Vistula's right bank, shelled Polish positions for the entire day.^[20] After two days of heavy fighting, with no ammunition or food rations remaining, further attempts at a breakout for the Poles became impossible.^[10]