The Battle of the Bzura (or the Battle of Kutno) was the largest battle of the German invasion of Poland and was fought from 9 to 19 September 1939.The Second World War: An Illustrated History , Putnam, 1975, , Google Print snippet (p.38)Sources vary regarding the end date, with some giving 18 September and others 19 September. Brockhaus Multimedial Lexikon gives 19 September 1939 as to the battle's end date. It was a Polish counter-attack against the Germans.
The battle took place west of Warsaw, near the Bzura River. It began as a Polish counter-offensive and achieved some initial success, but it faltered as the Germans ultimately outflanked the Polish forces with a concentrated counter-attack, which significantly weakened the Polish forces and resulted in the destruction of the Poznań and Pomorze Armies. The conclusion of the battle marked the completion of the German occupation of Western Poland.Zaloga, S.J., Poland 1939, Oxford, Osprey Publishing Ltd., 2002,
Background
The Polish plan to defend from the German invasion, Plan West, called for the defence of the borders.Seidner, Stanley S. Marshal Edward Śmigły-Rydz Rydz....,34-128. This strategy was dictated more by political than military concerns, as the Poles feared that the Germans, after they had taken over the territories that they had lost by the Treaty of Versailles, would try to end the war by retaining those territories. Defending the borders was risky, but the Poles were counting on a British and French counteroffensive, which never came. As a result, Army Pomorze, under General Władysław Bortnowski, found itself surrounded in the Polish Corridor by German forces on two fronts. Army Poznań, under General Tadeusz Kutrzeba, was pushed to the westernmost fringes of Poland and was separated from its primary defensive positions and from other Polish Armies.
The German offensive proved the folly of the Polish border defence plan during the first days of the war.Cisowski, Zalewski, Bitwa..., p.5 Army Pomorze was defeated at the Battle of Bory Tucholskie and was forced to retreat to the south-east. Army Poznań, meanwhile, did not face heavy German assaults but was forced to retreat to the east by defeats of its neighbours (Army Pomorze in the north and Army Łódź in the south). Both of them were retreating and so Army Poznań was in danger of being flanked and surrounded by the German forces. On 4 September, Army Poznań moved through Poznań and abandoned it to the enemy although at that point, it was not in contact with any significant German forces. By 6 September, Armies Pomorze and Poznań had linked and formed the strongest Polish operational unit in the campaign, and General Bortnowski accepted the command of General Kutrzeba.
On 7 September, the Polish forces became aware of the German push towards Łęczyca, which, if successful, could cut off the retreat route of Polish forces. By 8 September, advanced German troops reached Warsaw, which marked the beginning of the Siege of Warsaw. At the same time, German forces had lost contact with Army Poznań, and the German command assumed that the army must have been transported by rail to aid Warsaw's defence. They were unaware that in fact Army Poznań had merged forces with Army Pomorze, which they considered, since its defeat at Bory Tucholskie, to be no longer a significant threat. On 8 September, the Germans were certain that they had eliminated major Polish resistance west of the Vistula and so prepared to cross it and to engage the Polish forces on the other side.
Meanwhile, General Kutrzeba and his staff officers had suspected, even before the German invasion, that it would be the neighbouring armies that would bear the German attack and so they had developed plans for an offensive to the south to relieve Army Łódź.Cisowski, Zalewski, Bitwa..., p.6 During the first week of the campaign, however, those plans were rejected by the Polish commander-in-chief, Marshal Edward Rydz-Śmigły. By 8 September, Kutrzeba had lost contact with Rydz-Śmigły, who had relocated his command center from Warsaw to Brest. Those factors made Kutrzeba decide to go forward with his plan. His situation was dire, as German forces were close to surrounding his units: the German 8th Army had secured the southern bank of the Bzura river, and the German 4th Army had secured the northern bank of the Vistula, from Włocławek to Wyszogród, and its elements were attacking the rear of the Armies Pomorze and Poznań from the direction of Inowrocław and crossing the Vistula near Płock.
Opposing forces The Polish forces consisted of Army Poznań and Army Pomorze. The German forces included the 8th Army under Johannes Blaskowitz and 10th Army under Walther von Reichenau of Army Group South (Heeresgruppe Süd), elements of the 4th Army under Günther von Kluge of the Army Group North (Heeresgruppe Nord) and air support (Luftflotte 1 and Luftflotte 4).
Polish Division or BrigadeRegiments Army Poznań Kutrzeba Wielkopolska Cavalry Brigade Abraham 15th Uhlan Regiment 17th Uhlan Regiment 7th Mounted Rifles Regiment Podolska Cavalry BrigadeStrzelecki 6th Uhlan Regiment 9th Uhlan Regiment 14th Uhlan Regiment elements of Pomorska Cavalry Brigade 14th Infantry DivisionWład 55th Infantry Regiment 57th Infantry Regiment 58th Infantry Regiment 17th Infantry DivisionMozdyniewicz 68th Infantry Regiment 69th Infantry Regiment 70th Infantry Regiment 25th Infantry DivisionAlter 29th Infantry Regiment 56th Infantry Regiment 60th Infantry Regiment 26th Infantry DivisionBrzechwa-Ajdukiewicz 10th Infantry Regiment 18th Infantry Regiment 37th Infantry Regiment Army Pomorze Bortnowski 4th Infantry DivisionLubicz-Niezabitowski 14th Infantry Regiment 63rd Infantry Regiment 67th Infantry Regiment 15th Infantry DivisionPrzyjałkowski 59th Infantry Regiment 61st Infantry Regiment 62nd Infantry Regiment 16th Infantry Division Bohusz-Szyszko 64th Infantry Regiment 65th Infantry Regiment 66th Infantry Regiment 27th Infantry Division Drapella 23rd Infantry Regiment 24th Infantry Regiment 50th Infantry Regiment German CorpsDivision or BrigadeRegiments 8th Army Blaskowitz X Corps Ulex 24th Infantry Division Olbricht 31st Infantry Regiment 32nd Infantry Regiment 102nd Infantry Regiment 30th Infantry Divisionvon Briesen 6th Infantry Regiment 26th Infantry Regiment 46th Infantry Regiment XIII Corps von Weichs 10th Infantry Divisionvon Cochenhausen 20th Infantry Regiment 41st Infantry Regiment 85th Infantry Regiment 17th Infantry DivisionLoch 21st Infantry Regiment 55th Infantry Regiment 95th Infantry Regiment SS Leibstandarte "Adolf Hitler"Dietrich. 10th Army Reichenau XI Corps Leeb 18th Infantry Division Cranz 30th Infantry Regiment 51st Infantry Regiment 54th Infantry Regiment 19th Infantry Division Schwantes 59th Infantry Regiment 73rd Infantry Regiment 74th Infantry Regiment XVI Corps Hoepner 1st Panzer Division Schmidt 1st Panzer Regiment 2nd Panzer Regiment 1st Infantry Regiment 4th Panzer Division Reinhardt 35th Panzer Regiment 36th Panzer Regiment 12th Infantry Regiment 14th Infantry Division Weyer 11th Infantry Regiment 53rd Infantry Regiment 116th Infantry Regiment 31st Infantry Division Kämpfe 12th Infantry Regiment 17th Infantry Regiment 82nd Infantry Regiment XV Corps Hoth 2nd Light Division Stumme 25th Panzer Regiment 6th Mechanized Cavalry Regiment 7th Mechanized Cavalry Regiment 3rd Light Division Kuntzen 10th Panzer Regiment 8th Mechanized Cavalry Regiment 9th Mechanized Cavalry Regiment 4th Army Kluge II Corps Strauß 3rd Infantry Division Lichel 8th Infantry Regiment 29th Infantry Regiment 50th Infantry Regiment 32nd Infantry Division Böhme 4th Infantry Regiment 94th Infantry Regiment 96th Infantry Regiment III Corps Haase 50th Infantry Division Sorsche 121st Infantry Regiment 122nd Infantry Regiment 123rd Infantry Regiment Netze Infantry Brigade Gablenz Wehrmacht Reserves 208th Infantry Division Andreas 309th Infantry Regiment 337th Infantry Regiment 338th Infantry Regiment 213th Infantry Division Courbiere 318th Infantry Regiment 354th Infantry Regiment 406th Infantry Regiment 221st Infantry Division Pflugbeil 350th Infantry Regiment 360th Infantry Regiment 375th Infantry Regiment Luftwaffe Göring 1st Air Fleet Kesselring 4th Air FleetLohr
Battle The battle can be divided into three phases: Phase I – Polish offensive towards Stryków, aiming at the flank of the German 10th Army (9–12 September) Phase II – Polish offensive towards Łowicz (13–15 September) Phase III – German counterattack and eventual defeat of the Poles, who withdraw towards Warsaw and Modlin (16–19 September)
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.Cisowski, Zalewski, Bitwa..., p.8Cisowski, Zalewski, Bitwa..., p.11 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).Seidner, Stanley S. Marshal Edward Śmigły-Rydz Rydz...., 120-22. 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.Seidner, Stanley S. Marshal Edward Śmigły-Rydz Rydz....,124. 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.Elble Rolf, 1975, Die Schlacht an der Bzura im September 1939 aus deutscher und polnischer Sicht The cavalry brigades, supplemented with TKS and TK-3 reconnaissance tanks, moved to threaten the flanks and the rear of the advancing German units.Seidner, Stanley S. Marshal Edward Śmigły-Rydz Rydz....,124-125.
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. 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.
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.Cisowski, Zalewski, Bitwa..., p.9 German air superiority had a significant impact by making it very costly and difficult for the Poles to move units during the day. 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.