European Theatre The Invasion of Poland (1 September - 6 October 1939) Beginning in 1933, Germany pursued a policy of rapprochement with Poland, trying to improve German–Polish relations, culminating in the German–Polish Non-Aggression Pact of 1934. In 1935 Germany had hoped to manoeuvre Poland into the Anti-Comintern Pact, forming a cooperative front against the Soviet Union, and territorial concessions but the Poles feared that their independence would eventually be threatened altogether. Poland would have been granted territory of its own, to its northeast, in return for the reversal of German territorial losses, stipulated by the Treaty of Versailles, of the "Polish Corridor" and the city of Danzig.
Though Britain also refused to join the Pact in 1935, an agreement called The Stresa Front was made between France, Britain and Italy designed to keep Nazi Germany from extending beyond her present borders. In particular, these nations tried to block "German expansionism", especially the annexation of Austria. Even so, only two months later, the Anglo-German Naval Agreement was signed between the United Kingdom and Nazi Germany in June 1935. The UK had not discussed this with its Stresa partners and the front was seriously damaged. The effort failed entirely when, in 1936, Italy privately sanctioned the remilitarization of the Rhienland and the Anschluss of Austria and Britain signed on to the Anti-Comintern Pact on November 25, 1936. Further, both Britain and France were complicit in the 1938 Munich Agreement while Poland participated in the partition of Czechoslovakia that followed, although they were not part of the agreement. The Anti-Comintern Pact would be renewed on November 25, 1941 with all 12 Allied and Axis nations as signatories.
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 and instead, on 31 March 1937, Poland was backed by a guarantee from Britain and France that stated that Polish territorial integrity would be defended with their support. At the same time, Chamberlain and his supporters believed war could be avoided and hoped Germany would agree to leave the rest of Poland alone if a deal could be stuck regarding Danzig and the Polish Corridor.
However, with the surprise signing of the Molotov-Ribbentrop Pact on 23 August, the Soviet Union neutralized the possibility of German opposition to a campaign against Poland and war became possible. 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 western third of the country was to go to Germany and the eastern two-thirds to the Soviet Union. The German-Soviet assault was originally scheduled to begin on 26 August but on 25 August the Polish-British Common Defence 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. 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. Meanwhile, the number of increased overflights by high-altitude reconnaissance aircraft and cross border troop movements signalled that war was imminent.
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 but he was pressured into revoking the order by the French who, failing to realize that the Germans and Soviets were fully mobilized and concentrated at the Polish border, still hoped for a diplomatic settlement. On 1 September 1939, forces of the USSR invaded Poland without a formal declaration of war. The Soviet government announced that it was acting to protect the Ukrainians and Belarusians who lived in the eastern part of Poland. Facing 33 divisions and 11 independent brigades, the unprepared Polish forces in the east were quickly driven back. Although Poland had begun mobilization on 30 Aug 70% of their forces were in the North and West of the country and, though they declared war on the Soviet Union on 3 September, the Allied governments could not provide any meaningful support. Only the Advanced Air Striking Force of the RAF/AAF (10/4 bmbr and 2/6 ftr sqn's) and Polforce (3rd French Army) were enroute to Poland by 7 Sept.
On 29 August, prompted by the British, Germany had issued a diplomatic offer to intervene in the event of a Soviet attack in return for the city of Danzig and a plebiscite in the Polish Corridor within the year. This was accepted by the Polish government on 30 Aug and on 17 Sep Germany, aided by Slovakia, moved into Poland with 63 divisions and four independent brigades. The more mechanized elements of the German army quickly outstripped the slower Polish Army units and took up positions roughly along the Pisa, Narev, Vistula and San rivers, using it's Non-Aggression Pact with the Soviet Union to 'negotiate' the pre-arraigned end to the advance wherever the two forces met. The Germans would not advance against the Soviets and the Poles couldn't attack without losing German support. Likewise, it appeared that the Soviets could not advance without bringing Germany into the war against them. The Germans declared that they were committed to remain for as long as necessary, for all intents annexing western Poland.
The Winter War (30 November 1939 - 13 March 1940)
