Operation Battle of the Border
The 'Battle of the Border' was a series of battles fought between German and Slovak forces and Polish forces in Poland’s western border regions as the Germans launched their 'Weiss' (i) invasion of Poland (1/4 September 1939).
The Polish 'Plan Zachód' strategic scheme called for the defence of Poland’s western border regions in the event of a German invasion. Much of Poland’s new industry and major population centres were located in the border area, and especially in Silesia, but the length of the border was very difficult to defend properly. The plan was criticised by elements of the Polish military and Western, particularly French, advisers but supported by politicians who feared the effect of abandoning a significant part of the population to an enemy without a fight, and who were further discouraged from abandoning those territories as Poland’s allies, France and the UK, did not and indeed could not guarantee the Polish borders and might well decide to allow the Germans to take the Polish 'corridor' that they demanded in exchange for peace.
'Weiss' (i) called for the start of hostilities before any declaration of war and for the Blitzkrieg doctrine of lightning war to be pursued. In 'Weiss' (i), German formations and units were to invade Poland from three directions: eastward from the German mainland through the western Polish border, southward from the exclave of East Prussia, and northward and north-eastward from Slovakia with the support of allied Slovak formations and units. All three axes were to converge on Warsaw, the Polish capital, while the main strength of the Polish army was to be encircled and destroyed in the regions to the west of the Vistula river.
Possessing a smaller population and thus a smaller military budget and army than those of Germany, Poland was further disadvantaged by the fact that the country was unsure when the war would start, and its armed forces had not been fully mobilised by 1 September.
The 'Battle of the Border' began at about 05.00 as German forces began to cross the Polish border in many places. The 'Battle of Westerplatte', which is often described as having begun as 04.45 with firing of the salvoes from the German pre-dreadnought battleship Schleswig-Holstein against Polish coastal fortifications, is commonly described as the first battle of the war. Other sources have described the 04.45 salvoes as happening 'minutes after Luftwaffe attacks on Polish airfields'. Several historians have identified the war’s first action as the bombing of the key Tczew bridge in the Polish 'corridor' by dive-bombers at about 04.30. The Himmler' false-flag operation had begun hours earlier.
At 08.00, German troops attacked near the Polish town of Mokra, so triggering the 'Battle of the Border' proper. Later that day, the Germans opened fronts along Poland’s western, southern and northern borders, while German aircraft began raids on Polish cities. The main routes of attack were directed to the east from Germany proper through Poland’s western border. A second route carried supporting attacks from East Prussia in the north, and there was a collaborative German and Slovak tertiary attack from German-allied Slovakia in the south.
In the north-west, Heeresgruppe 'Nord' commanded by Generaloberst Fedor von Bock attacked Pomerania and Greater Poland, moving from Germany proper (General Günther von Kluge’s 4th Army) and from East Prussia (General Georg von Küchler’s 3rd Army). In the 'Battle of the Tuchola Forest', which lasted from 1 to 5 September, the German forces split Generał dywizji Władysław Bortnowski’s Armia 'Pomorze', which was tasked with the defence of the Polish 'corridor', though parts of this army, under the command of Admiral Józef Unrug continued to defend pockets of the coast over the next few days or weeks in the 'Battle of Westerplatte', the 'Battle of Gdynia', the 'Battle of Hel' and others, while the rest of the Armia 'Pomorze', together with Generał dywizji Tadeusz Kutrzeba’s Armia 'Poznań', was forced to retreat to the east from their defensive lines in Greater Poland towards Kłodawa in Kujawy.
In northern Polish region of Masovia, by 3 September, part of the 3rd Army had defeated Generał dywizji Emil Krukowicz-Przedrzymirski’s Armia 'Modlin' in the 'Battle of Mława'. The Polish forces retreated toward their secondary lines of defence on the Vistula and Narew rivers, allowing the Germans to move toward their main objective, the Polish capital of Warsaw.
In the south and south-west, Generaloberst Gerd von Rundstedt’s Heeresgruppe 'Süd' struck along the lines dividing Generał dywizji Juliusz Rómmel’s Armia 'Łódź' from the Armia 'Poznań' in the north and Generał dywizji Antoni Szylling’s Armia 'Kraków' in the south. Despite several Polish tactical victories, such as that in the 'Battle of Mokra' on 1 September, the Polish forces were soon and steadily forced to retreat, as the Armia 'Łódź' was being outflanked by General Johannes Blaskowitz’s 8th Army and General Walter von Reichenau’s 10th Army. The Armia 'Kraków' was retreating from Silesia, and, in the south, Generał dywizji Kazimierz Fabrycy’s Armia 'Karpaty' was being slowly pushed to the north in the direction of the Dunajec and Nida rivers by General Wilhelm List’s 14th Army.
By 6 September the Polish forces were in retreat and Marszałek Polski Edward Rydz-Śmigły, the Polish commander-in-chief, ordered all formations to fall back to the secondary lines of defences on the Vistula and San rivers.
Nearly all of the fighting is considered to have been part of the 'Battle of the Border', the major exceptions being the 'Battle of Hel, which lasted for more than one month, and the 'Battle of Mokra', a Polish defensive victory. The 'Battle of the Border' resulted in the rapid defeat of the Polish forces, which were forced to abandon the Pomerania, Greater Poland and Silesia. Those defeats in turn made it more difficult for the Polish forces to fall back in an organised manner to the secondary lines of defence behind the Vistula river and near the Romanian 'bridgehead'.
The 'Battle of the Border' included the 'Defence of the Polish Post Office in Danzig' on 1 September, the 'Battle of Chojnice' on 1 September, the 'Skirmish of Krojanty' on 1 September, the 'Battle of Lasy Królewskie' on 1 September, the 'Battle of Mokra' on 1 September, the 'Defence of Katowice on 3/4 September, the 'Battle of Pszczyna' on 1/4 September, the 'Battle of Grudziądz' on 1/3 September, the 'Battle of Mława and Ciechanow' on 1/4 September, the 'Battle of Jordanów' on 2 September, the 'Raid on Fraustadt' on 2 September, the 'Battle of Węgierska Górka' on 1/3 September, the 'Battle of the Tuchola Forest' on 1/5 September, the 'Battle of Borowa Góra' on 2/5 September, the 'Battle of Westerplatte' on 1/7 September, the 'Battle of Różan' on 4/6 September, the 'Battle of Piotrków Trybunalski' on 5/6 September, the 'Battle of Tomaszów Mazowiecki' on 6 September, the 'Battle of Wizna' on 6/10 September, and the 'Battle of Hel' on 1 September/2 October.