The campaign against Poland in September 1939 (Part I). Deployment, the German attack and the advance on Warsaw until 9 September.
The German attack on Poland began on September 1, 1939, at 4:45 a.m., when the old German pre-dreadnought ‘Schleswig-Holstein’ fired on the Polish fortification on the Westerplatte off Danzig (Gdansk).
Deployment for the Polish campaign
For the Polish campaign the Wehrmacht was able to deploy 37 infantry and 3 mountain divisions and all existing 6 Panzer divisions, 4 light divisions and 4 motorized divisions as well as a cavalry brigade.
These included 3,195 tanks, of which only 98 were Panzer III and 211 Panzer IV.
With 38 infantry divisions, a motorized brigade and 11 cavalry brigades, the Polish Army was almost equally strong on paper. However, there were only 1,134 light and small, older tanks.
In addition, another motorized brigade and two infantry divisions were close to completion.
However, the Polish Air Force had only 745, mostly outdated, aircraft. See also: Polish Armed Forces.
The German Army Group North under General von Bock was ready with the 4th Army (von Kluge) and the XIXth Panzer Corps in Pomerania, as well as with the 3rd Army (von Küchler) in East Prussia. The Army Group South under Colonel General von Rundstedt in Silesia consisted from North to South of the 8th Army (Blaskowitz), the 10th Army (von Reichenau) and the 14th Army (List). See also: German Orders of Battle for September 1, 1939.
The allied French had been urging the Poles for some time to adopt a flexible strategic defense in order to gain time until the Allied troops were built up in the West. Poland, however, was dependent on securing its important cereal and industrial centers, which is why they originally intended to defend only a ‘rump area’.
However, Poland had already begun a partial mobilization in March 1939, including the entire corridor between East Prussia and the German Reich, as well as the fortress of Poznan in this area of defense. Optimistic deployment plans for a thrust from the Poznan area to Berlin were also planned, after France and Britain had been determined as allies.
Thus, in September the Polish units were distributed and fragmented over the entire border, so that instead of defending everything, nothing could be defended at all. By August 27, 1939, Polish mobilization had entered its final phase.
France began pre-mobilization as early as 21 August 1939, whereupon war readiness was achieved ten days later.
Germany had only begun an initial secret mobilization on August 26, whereby full readiness for war could only be achieved after at least eight days. However, the active army was already made war-ready on 16 August and the reservists for the reserve divisions of the first wave were called up. The deployment against Poland was camouflaged in East Prussia with troop parades for the celebrations of the anniversary of the Tannenberg Battle and in Silesia and Pomerania with autumn maneuvers and the construction of an ‘Eastern Wall’.
The German attack had originally been planned for 26 August 1939, but Hitler hesitated and hoped for a diplomatic solution for Danzig (Gdansk) and the corridor and postponed the ‘Fall Weiss’ (‘White Case’) by six days.
Since after the ‘Great War’ from 1914 to 1918 a lively and controversial discussion had broken out about the question of war guilt in Europe, which primarily referred to the course of the ordered mobilizations as the cause instead of the formal declarations of war that actually only after that took place, all governments endeavored to keep their war preparations as secret as possible and did not want them to be understood as ‘official mobilization’.
Hitler also considered another trick necessary to convince the world of the Polish war guilt. He ordered a fictitious attack with men in Polish uniforms on the German radio station Gleiwitz carried out shortly before the German attack. But the swindle was soon discovered and nothing happened with the alibi.
He also considered formal declarations of war after the experiences in the days before World War One and their evaluations by the war guilt clause of the Treaty of Versailles as outdated.
German attack on Poland
Thus, on this fateful early morning of 1 September 1939, German troops already crossed the Polish border in numerous places without declaring war, which was actually only supposed to be a limited local campaign.
Also, the German air force began with strong attacks on the Polish airfields, which were however in vain, since the Polish squadrons were already distributed the day before on provisional field airfields. However, the Germans had absolute air superiority from the beginning and could support their ground troops at will and attack important operational and tactical targets in Poland.
The German plan was aimed at rapid success in the first modern ‘blitzkrieg’ in history, as time was scarce because of the danger of Western intervention. For this, the German 10th Army in the south should trap strong Polish units close to the border in order to rule out further resistance in the interior behind the Vistula and the 3rd Army should quickly establish the connection with East Prussia through the corridor. Then the 3rd Army was to advance south to close a huge pocket in western Poland together with the 10th Army.
Both failed because the 10th Army had to advance over 185 miles (300 kilometers) of bad sand roads and the Polish Uhlans Brigade of Colonel Filipowicz – fighting mainly on foot as infantrymen – on the southern flank of the Lodz Army (General Ròmmel – not to be confused with the later German ‘Desert Fox’) stopped the German 4th Panzer Division (one of the two tank divisions of the 10th Army) on the very first day. This battle is one of the few in World War II where a cavalry unit was successful against tanks.
The Poles, on the other hand, distributed their available tank combat vehicles among 15 independent tank companies, each of which was distributed among an infantry division and thus had no meaningful operational combat power.
In the north there are also delays, because the Poles succeed in blowing up the Vistula Bridge near Dirschau before the arrival of a German armored train with Stuka support. In addition, the German Panzer Corps under Guderian had been integrated into an infantry army, which reduced its speed. The German leadership still lacked the necessary experience in motorized warfare.
Nevertheless, Guderian managed to reach the Vistula and trapped two Polish infantry divisions with a cavalry brigade in the ‘corridor’. The Pomeranian army lost almost half its troops and had to retreat to Thorn and Bydgoszcz, allowing the German troops to connect with East Prussia.
On the next day, Sunday, September 2, 1939, the situation for the Krakow army facing the German 10th Army became critical, however, and the latter had to begin its retreat in the evening. This retreat took place under strong pressure of the German motorized units. Here was also the focus of the German tank troops, as it was the shortest route to Warsaw.
But despite the Polish mistakes in the deployment and night-long, exhausting retreat marches of their troops, the Wehrmacht did not succeed in encircling any significant parts of the Polish army.
Also, the advance from the north was stopped by the Polish field fortifications near Mlawa and before Warsaw itself was the strong fortress Modlin, so that the two armies of the Army Group North had to overcome the defended river systems east of the Polish capital.
On September 2, the governments of London and Paris demanded the cessation of the German attack on Poland, and when the ultimatum expired, Britain and France declared war on Germany on September 3, 1939. Thus, to Hitler’s surprise, the limited range of arms had turned into another world war. From now on the ‘Great War’ from 1914 to 1918 was to be called the ‘First World War’ and Hitler’s attack on Poland would enter history books as the outbreak of the ‘Second World War’.
Mussolini refused to enter the war on German side without such great material aid, which Hitler could not afford, and Italy remained neutral. Thus, Germany was once again in a war on two fronts against overpowering opponents with worldwide resources, which had to appear hopeless. For Hitler, however, there was now only the flight to the front, namely a victory over Poland as quickly as possible.
Advance towards Warsaw
Already on 3 September, the Polish Minister of War, General Kaspruycki, received the order to prepare the defense of Warsaw. The army Modlin north of the capital still successfully defended the fortification line near Mlawa against the German I Army Corps, but has to retreat in the night from 3 to 4 September due to imminent outwit.
On September 4, the Southern Army Group ordered its 14th Army to advance to the San to prevent the withdrawal of Polish units from the Kielce and Radom regions and to march on Warsaw. This would also cut off the Polish troops at Lodz and Poznan.
On the same day, the Polish army Modlin was subjected to heavy German air raids and, under this pressure, crossed the Vistula to the east, leaving Warsaw uncovered to the north.
On 6 September, the French armed forces launched an alibi offensive against the Saar, to which they were committed in their long-standing alliance treaty with Poland. The ‘offensive’, however, only led to the occupation of the apron of the Siegfried Line (Western Wall) evacuated by the Germans, and British and French missed the unique opportunity to advance as far as the Rhine and the Ruhr, and instead stood idly by and watch Poland’s perish.
Due to the French activities and the failure to trap significant parts of the Polish army in the first days of the Polish campaign, the German High Command of the Army adopted a daring maneuver. Despite the imminent danger in the West, the German motorized divisions were to advance in a sweeping encircling movement east of the Vistula in Poland as far as to Przemysl and Lemberg in order to carry out a decisive pincer movement in the third attempt.
Thus, the risk was taken that the Western Allies could advance as far as the Ruhr area before the German tank divisions could be brought in from the depths of Poland to the West.
This decision was very serious for the German chief of general staff Halder and the commander-in-chief of the army, von Brauchitsch, but they wanted to eliminate the Polish armed forces in order not to have to leave any more troops in the East. Then the Wehrmacht in the West would be as strong as the French and the British together.
The next day, September 7, the Polish head of government and commander-in-chief Marshal Rydz-Smigly moved his headquarters from Warsaw to Brest Litovsk and ordered his commanders to gather with their troops east of Lviv.
The German leadership rightly recognized that the Poles would refrain from defending the Vistula in order to be able to retreat in the east into friendly Romania. Therefore, the 4th Army of the Army Group North should advance along the Vistula to the southeast on Warsaw, while the Army Group South should enclose the Army Group Lodz even before the Vistula. The 14th Army of the Army Group South, on the other hand, was to advance in the direction of Lublin – later Lemberg – in order to prevent the Poles from retreating to Romania.
In the next three days a race to the Vistula took place between the Poles and the Germans.
Already on Friday, September 8, German tank troops arrived at the middle reaches of the Vistula River and the southwestern suburbs of Warsaw in the evening, thus thwarting the withdrawal of the Polish armies Pmorze, Pozan, Lodz as well as large parts of the Prusy and Krakow armies.
The German 10th Army trapped the rest of the Prusy Army at Random and reached the Vistula, while the 4th Panzer Division of Lieutenant General Reinhardt reached Warsaw.
These movements trapped the reserves of the Poles and practically eliminated the first eight divisions, which was the first great success of German ‘Blitzkrieg’ Panzer tactics. The rapid advance of these motorized troops without flank protection differed greatly from the battles of the First World War and reminded nostalgics of the fast cavalry corps of the times up to the end of the Napoleonic Wars.
However, Warsaw could not be conquered practically from the movement and the 4th Panzer Division lost 57 of its 120 attacking tanks to the Polish defenders within three hours on 9 September. The Polish troops cut off to the west of the Vistula were now all pushing in the direction of their capital.
Here to Part II: End of Polish campaign.