Operation Fall Weiss



29 September Britain and France agree to German demands that Czechoslovakia cede the Sudetenland at the Munich conference,

1-7 October German troops occupy the Sudetenland in Czechoslovakia


15 March German army invades the remainder of Czechoslovakia, occupies Bohemia-Moravia and eventually allows Slovakia to form puppet state

22 March Germany seizes port of Memel from Lithuania

25 March Hitler orders start of preparations to invade Poland March Polish army begins partial mobilisation in response to German diplomatic pressure to cede Pomeranian corridor and allow return of Danzig to Germany

31 March British government announces its guarantee of Polish security, including maintaining the status quo of Danzig

May Polish and French general staff hold meetings in France, during which France pledges major offensive against Germany two weeks after an invasion

23 August German foreign minister Ribbentrop and Soviet foreign minister Molotov announce German-Soviet non-aggression pact; which includes secret clauses agreeing to the dismemberment of Poland

24 August Britain gives written assurances to Poland in the event of war with Germany

26 August Hitler planned to start war today, but postpones the attack in wake of British security announcement

1 September War begins at 0400hrs with German battleship Schleswig-Holstein firing at Polish garrison on Westerplatte near Danzig

2 September German advances out of East Prussia force Army Modlin to withdraw to Vistula line

3 September France and Britain declare war on Germany

5 September Piotrkow falls, and the gateway to Warsaw is opened to German Panzers; in the evening, Armies Lodz, Krakow, Prusy and Poznan ordered to begin retreat behind the Vistula

7 September German tanks reach outskirts of Warsaw, but are thrown back in intense street fighting. Marshal Rydz-Smigly decides to shift headquarters from Warsaw to Brzesc-nad-Bugiem

9 September Army Poznan launches counter-attack along the Bzura River, catching the German 8th Army off guard

15 September Army Group North reaches northern outskirts of Warsaw, siege resumes

16 September Polish forces along the Bzura subjected to massive artillery and air attack; retreat to Warsaw ordered that evening

17 September Red Army begins to invade Poland from the east

19 September Army Krakow attempts to break out towards Romania through Tomaszow Lubelski

21 September Last units from Bzura counter-offensive finally surrender

22 September Encircled by German and Soviet troops, city of Lwow finally surrenders

25 September 'Black Monday', a massive Luftwaffe attack on Warsaw causes heavy civilian casualties

26 September Southern Warsaw forts captured

27 September Warsaw garrison surrenders

29 September Fortified Modliri garrison surrenders

6 October Battlegroup under General Franciszek Kleeberg surrenders after a four-day battle around Kock; last major Polish unit in the field

The Invasion of Poland 18, also known as Fall Weiss (Case White) in Germany, was an invasion of Poland by Germany, the Soviet Union, and a small Slovak contingent that marked the beginning of World War II in Europe. The German invasion began on 1 September 1939, one week after the signing of the Molotov–Ribbentrop Pact, while the Soviet invasion commenced on 17 September 1939 following the Molotov-Tōgō agreement which terminated the Nomonhan incident on 16 September 1939. The campaign ended on 6 October 1939 with Germany and the Soviet Union dividing and annexing the whole of Poland.

The morning after the Gleiwitz incident, German forces invaded Poland from the north, south, and west. As the Germans advanced, Polish forces withdrew from their forward bases of operation close to the Polish–German border to more established lines of defence to the east. After the mid-September Polish defeat in the Battle of the Bzura, the Germans gained an undisputed advantage. Polish forces then withdrew to the southeast where they prepared for a long defence of the Romanian Bridgehead and awaited expected support and relief from France and the United Kingdom. The two countries had pacts with Poland and had declared war on Germany on 3 September, though in the end their aid to Poland in the September campaign was very limited.

The Soviet Red Army's invasion of Eastern Poland on 17 September, in accordance with a secret protocol of the Molotov–Ribbentrop Pact, rendered the Polish plan of defence obsolete. Facing a second front, the Polish government concluded the defence of the Romanian Bridgehead was no longer feasible and ordered an emergency evacuation of all troops to neutral Romania.

On 6 October, following the Polish defeat at the Battle of Kock, German and Soviet forces gained full control over Poland. The success of the invasion marked the end of the Second Polish Republic, though Poland never formally surrendered. 19

On 8 October, after an initial period of military administration, Germany directly annexed western Poland and the former Free City of Danzig and placed the remaining block of territory under the administration of the newly established General Government. The Soviet Union incorporated its newly acquired areas into its constituent Belarusian and Ukrainian republics, and immediately started a campaign of sovietization. In the aftermath of the invasion, a collective of underground resistance organizations formed the Polish Underground State within the territory of the former Polish state. Many of the military exiles that managed to escape Poland subsequently joined the Polish Armed Forces in the West, an armed force loyal to the Polish government in exile.

In 1933, the National-Socialist German Workers' Party20, under its leader Adolf Hitler, came to power in Germany. As early as the autumn of 1933 Hitler envisioned annexing such territories as Bohemia, Western Poland, Austria to Germany and creation of satellite or puppet states without economies or policies of their own.21 As part of this long term policy, Hitler at first pursued a policy of rapprochement with Poland, trying to improve German–Polish relations, culminating in the German–Polish Non-Aggression Pact of 1934. Earlier, Hitler's foreign policy worked to weaken ties between Poland and France, and attempted to manoeuvre Poland into the Anti-Comintern Pact, forming a cooperative front against the Soviet Union. Poland would be granted territory of its own, to its northeast in Ukraine and Belarus if it agreed to wage war against Soviet Union, but the concessions the Poles were expected to make meant that their homeland would become largely dependent on Germany, functioning as little more than a client state. The Poles feared that their independence would eventually be threatened altogether. To provoke war with Poland in order to gain Lebensraum, Nazis used as a pretext a claim to Free City of Danzig and Polish territory that separated German exclave of East Prussia from the rest of the Reich. The so-called Polish Corridor constituted land long disputed by Poland and Germany, and inhabited by a Polish majority. The Corridor became a part of Poland after the Treaty of Versailles. Many Germans also wanted the city of Danzig and its environs (together the Free City of Danzig) to be reincorporated into Germany. Danzig was a port city with a German majority. It had been separated from Germany after Versailles and made into a nominally independent Free City of Danzig. Hitler sought to use this as reason for war, reverse these territorial losses, and on many occasions made an appeal to German nationalism, promising to "liberate" the German minority still in the Corridor, as well as Danzig. 22 Poland participated in the partition of Czechoslovakia that followed the Munich Agreement, although they were not part of the agreement. It coerced Czechoslovakia to surrender the region of Český Těšín by issuing an ultimatum to that effect on 30 September 1938, which was accepted by Czechoslovakia on 1 October.

By 1937, Germany began to increase its demands for Danzig, while proposing that a roadway be built in order to connect East Prussia with Germany proper, running through the Polish Corridor. Poland rejected this proposal, fearing that after accepting these demands, it would become increasingly subject to the will of Germany and eventually lose its independence as the Czechs had. Polish leaders also distrusted Hitler. Furthermore, Germany's collaboration with anti-Polish Ukrainian nationalists from the Organization of Ukrainian Nationalists, which was seen as an effort to isolate and weaken Poland, weakened Hitler's credibility from the Polish point of view. The British were also aware of the situation between Germany and Poland. On 31 March 1939 the Anglo-Polish military alliance was formed by Britain and France, ensuring that Polish independence and territorial integrity would be defended with their support if it were to be threatened by Germany. On the other hand, British Prime Minister Neville Chamberlain and his Foreign Secretary, Lord Halifax, still hoped to strike a deal with Hitler regarding Danzig (and possibly the Polish Corridor), and Hitler hoped for the same. Chamberlain and his supporters believed war could be avoided and hoped Germany would agree to leave the rest of Poland alone. German hegemony over Central Europe was also at stake. In private Hitler revealed in May that Danzig was not the real issue to him, but pursuit of Lebensraum for Germany

With tensions mounting, Germany turned to aggressive diplomacy as well. On 28 April 1939, it unilaterally withdrew from both the German-Polish Non-Aggression Pact of 1934 and the London Naval Agreement of 1935. Talks over Danzig and the Corridor broke down and months passed without diplomatic interaction between Germany and Poland. During this interim, the Germans learned that France and Britain had failed to secure an alliance with the Soviet Union against Germany, and that the Soviet Union was interested in an alliance with Germany against Poland. Hitler had already issued orders to prepare for a possible "solution of the Polish problem by military means"—a Case White scenario.

In May 1939, in a statement to his generals while they were in the midst of planning the invasion of Poland, Hitler made it clear that the invasion would not come without resistance as it had in Czechoslovakia:

With minor exceptions German national unification has been achieved. Further successes cannot be achieved without bloodshed. Poland will always be on the side of our adversaries... Danzig is not the objective. It is a matter of expanding our living space in the east, of making our food supply secure, and solving the problem of the Baltic states. To provide sufficient food you must have sparsely settled areas. There is therefore no question of sparing Poland, and the decision remains to attack Poland at the first opportunity. We cannot expect a repetition of Czechoslovakia. There will be fighting. However, with the surprise signing of the Molotov-Ribbentrop Pact on 23 August, the denouncement of secret Nazi-Soviet talks held in Moscow, Germany neutralized the possibility of Soviet opposition to a campaign against Poland and war became imminent. In fact, the Soviets agreed to aid Germany in the event of France or the UK going to war with Germany over Poland and, in a secret protocol of the pact, the Germans and the Soviets agreed to divide Eastern Europe, including Poland, into two spheres of influence; the western⅓ of the country was to go to Germany and the eastern⅔ to the Soviet Union. The German assault was originally scheduled to begin at 04:00 on 26 August. However, on 25 August, the Polish-British Common Defense Pact was signed as an annex to the Franco-Polish Military Alliance. In this accord, Britain committed itself to the defence of Poland, guaranteeing to preserve Polish independence. At the same time, the British and the Poles were hinting to Berlin that they were willing to resume discussions—not at all how Hitler hoped to frame the conflict. Thus, he wavered and postponed his attack until 1 September, managing to in effect halt the entire invasion "in mid-leap".

However, there was one exception: in the night of 25–6 August, a German sabotage group which had not heard anything about a delay of the invasion made an attack on the Jablunkov Pass and Mosty railway station in Silesia. On the morning of 26 August, this group was repelled by Polish troops. The German side described all this as an incident "caused by an insane individual" (see Jabłonków Incident). On 26 August, Hitler tried to dissuade the British and the French from interfering in the upcoming conflict, even pledging that the Wehrmacht forces would be made available to Britain's empire in the future. The negotiations convinced Hitler that there was little chance the Western Allies would declare war on Germany, and even if they did, because of the lack of "territorial guarantees" to Poland, they would be willing to negotiate a compromise favourable to Germany after its conquest of Poland. Meanwhile, the increased number of overflights by high-altitude reconnaissance aircraft and cross border troop movements signaled that war was imminent.

On 29 August, prompted by the British, Germany issued one last diplomatic offer, with Fall Weiss "Case White" yet to be rescheduled. That evening, the German government responded in a communication that it aimed not only for the restoration of Danzig but also the Polish Corridor (which had not previously been part of Hitler’s demands) in addition to the safeguarding of the German minority in Poland. It said that they were willing to commence negotiations, but indicated that a Polish representative with the power to sign an agreement had to arrive in Berlin the next day while in the meantime it would draw up a set of proposals. The British Cabinet was pleased that negotiations had been agreed to but, mindful of how Emil Hacha had been forced to sign his country away under similar circumstances just months earlier, regarded the requirement for an immediate arrival of a Polish representative with full signing powers as an unacceptable ultimatum. On the night of 30/31 August, German Foreign Minister Joachim von Ribbentrop read a 16-point German proposal to the British ambassador. When the ambassador requested a copy of the proposals for transmission to the Polish government Ribbentrop refused on the grounds that the requested Polish representative had failed to arrive by midnight. When Polish Ambassador Lipski went to see Ribbentrop later on 31 August to indicate that Poland was favorably disposed to negotiations, he announced that he did not have the full power to sign, and Ribbentrop dismissed him. It was then broadcast that Poland had rejected Germany's offer, and negotiations with Poland came to an end. Hitler issued orders for the invasion to commence soon afterwards.

On 29 August, German saboteurs planted a bomb at the railway station in Tarnów and killed 21 passengers, leaving 35 wounded. On 30 August, the Polish Navy sent its destroyer flotilla to Britain, executing Operation Peking. On the same day, Marshal of Poland Edward Rydz-Śmigły announced the mobilization of Polish troops. However, he was pressured into revoking the order by the French, who apparently still hoped for a diplomatic settlement, failing to realize that the Germans were fully mobilized and concentrated at the Polish border. During the night of 31 August, the Gleiwitz incident, a false flag attack on the radio station, was staged near the border city of Gleiwitz by German units posing as Polish troops, in Upper Silesia as part of the wider Operation Himmler. On 31 August 1939, Hitler ordered hostilities against Poland to start at 4:45 the next morning. Because of the prior stoppage, Poland managed to mobilize only 70% of its planned forces, and many units were still forming or moving to their designated frontline positions.

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