Invasion of Poland (1939)

Invasion of Poland (1939), also known as the September Campaign, marked the beginning of World War II in Europe. Initiated by Nazi Germany under Adolf Hitler on 1 September 1939, the campaign saw the subsequent invasion from the east by the Soviet Union on 17 September, in accordance with the secret protocols of the Molotov–Ribbentrop Pact. The joint Axis assault led to the defeat of the Polish armed forces and the division of Poland between Germany and the Soviet Union, a partition formalized by the German–Soviet Frontier Treaty.

Background

The invasion was the culmination of escalating tensions following Adolf Hitler's rise to power and the aggressive expansionist goals outlined in his ideology of Lebensraum. The immediate pretext was the staged Gleiwitz incident, a false-flag operation conducted by Germany's SS to simulate a Polish attack. This followed the diplomatic failure of the Munich Agreement and Germany's subsequent occupation of the Czech lands, which had isolated Poland. Crucially, the Molotov–Ribbentrop Pact, signed between German Foreign Minister Joachim von Ribbentrop and his Soviet counterpart Vyacheslav Molotov, contained secret protocols dividing Eastern Europe into spheres of influence, ensuring Soviet non-interference and later participation. Guarantees of Polish independence by Britain and France under the Anglo-Polish military alliance set the stage for a broader European conflict.

Opposing forces

The German Wehrmacht deployed two army groups, Army Group North under Fedor von Bock and Army Group South under Gerd von Rundstedt, utilizing the novel combined-arms doctrine of Blitzkrieg. This integrated rapid advances by Panzer divisions like the 1st Panzer Division with overwhelming air support from the Luftwaffe, commanded by Hermann Göring. The Polish Armed Forces, commanded by Marshal Edward Rydz-Śmigły, were organized into seven armies, including the Pomorze Army and Kraków Army. While numerous, Polish forces were significantly outmatched in modern equipment, particularly in armor and aircraft like the Messerschmitt Bf 109, and were strategically disadvantaged by their forward deployment plan, Plan Zachód. A smaller contingent from the Slovak Republic participated in the south, while the massive Red Army invasion force later included the Belorussian Front and Ukrainian Front.

Course of the war

Hostilities commenced at 04:45 on 1 September with the Battle of Westerplatte and the bombing of Wieluń. The Luftwaffe achieved air superiority early, devastating Polish logistics and cities like Warsaw. Key armored breakthroughs occurred at the Battle of the Bzura and the Battle of Tomaszów Lubelski, where German pincer movements encircled large Polish formations. The Battle of Wizna, though a heroic Polish delay action, exemplified the overwhelming German tactical advantage. On 17 September, the Soviet Union invaded from the east, violating the Soviet–Polish Non-Aggression Pact and shattering any hope of an organized Polish defense in the Kresy region. Major organized resistance ended with the Battle of Kock on 6 October, though the besieged capital, Warsaw, had capitulated earlier after sustained bombardment. Key naval engagements included the Battle of the Danzig Bay and the escape of vessels like ORP *Orzeł* to Allied ports.

Aftermath

The campaign concluded with the complete military defeat of Poland and its fourth partition, formalized by the German–Soviet Frontier Treaty. Nazi Germany annexed western Poland into Reichsgau Wartheland and the General Government occupation zone, immediately initiating a brutal campaign of terror, including the Intelligenzaktion and the later establishment of extermination camps like Auschwitz. The Soviet Union annexed eastern territories, a move followed by mass deportations to the Gulag and events like the Katyn massacre. The Polish government-in-exile was established first in Angers and later in London, continuing the fight through the Polish Armed Forces in the West and the Polish Underground State. The invasion triggered the previous year, and the Second World War, as ack|Wikillegacy of the war, the war, the invasion of the war, the War II, the war, the War of the, the War of the War of the War of the war, the War of the war of the war, War the war the war the war the war the war the war the war the war the war the war, War the war the war the war the war the war the war the war the war, war the war the war the war the war the war the war the war the war the war, war the war the war the war the war the war the war the war the war the war the war war the war the war, the war the war the war the war the war the war the West the war the war the war the war the war the war the war the war the war the war the war the war the war the war the war the war the war the war the war the war, war the war the war the war the war the war the war the war, war the war the war the the the war, war the war the war the war the war the war|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|Polish Republic|London and 2-{{{{{{{

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