Defence of Poland (1939)

Defence of Poland (1939)
Conflict	Invasion of Poland
Partof	World War II
Date	1 September – 6 October 1939
Place	Poland, Free City of Danzig, East Prussia, West Prussia, Silesia
Result	Partition of Poland by Nazi Germany and the Soviet Union; beginning of World War II in Europe
Combatant1	Poland
Combatant2	Nazi Germany; from 17 September Soviet Union
Commander1	Edward Rydz-Śmigły; Władysław Sikorski; Józef Beck
Commander2	Adolf Hitler; Hermann Göring; Walther von Brauchitsch; Georgy Zhukov (Soviet operations leadership)
Strength1	approx. 1,000,000 mobilized; limited armoured and aircraft resources
Strength2	approx. 1,800,000; superiority in armoured forces and Luftwaffe
Casualties1	military killed and wounded; civilian casualties substantial
Casualties2	military killed and wounded; captured

Defence of Poland (1939)

The defence of Poland in 1939 was the armed response of the Second Polish Republic to the coordinated aggression that triggered the European phase of World War II. Polish forces confronted invasions from Nazi Germany beginning on 1 September 1939 and from the Soviet Union on 17 September 1939, involving major operations across regions such as Masovia, Greater Poland, Pomerania, and Podlachia. The campaign combined movements by the Wehrmacht and the Red Army with Luftwaffe bombing, resulting in the rapid defeat and subsequent occupation, exile of leadership, and emergence of organized Polish resistance.

Background and Prelude

In the aftermath of the Treaty of Versailles and interwar settlements, territorial disputes involving Free City of Danzig and the Polish Corridor exacerbated Polish–German tensions. Diplomatic crises including the Gleiwitz incident and the series of demands by Adolf Hitler on Józef Beck paralleled the failure of guarantees from United Kingdom and France to deter aggression. The strategic context included competing plans by Heinrich Himmler and Hermann Göring for occupation, the rise of Generalplan Ost concepts in Nazi policy, and Soviet diplomatic maneuvering after the Molotov–Ribbentrop Pact signed by Vyacheslav Molotov and Joachim von Ribbentrop.

German and Soviet Invasion Plans

Nazi Germany prepared Fall Weiss with forces concentrated from East Prussia and Wehrkreis sectors, employing Panzergruppe formations and air power from the Luftwaffe under Hermann Göring. The strategy relied on pincer movements via Silesia and Pomerania to encircle Polish armies near Warsaw and Łódź, integrating mechanized corps led by commanders such as Heinz Guderian and Fedor von Bock. Concurrently, the secret protocols of the Molotov–Ribbentrop Pact allocated eastern Poland to the Soviet Union, enabling Joseph Stalin to authorize the Red Army to invade, deploying units from the Belarusian Military District and Ukrainian Military District under staffs influenced by Kliment Voroshilov and Semyon Timoshenko.

Course of the Campaign

Operations began with intense bombardment by the Luftwaffe and rapid advances by Wehrmacht formations that cut communications between Polish operational zones. Early battles such as the Battle of Westerplatte, the Battle of Mokra, and the Defense of the Polish Post Office in Danzig signaled fierce local resistance. Encirclement battles around Krojanty and the collapse of frontier defenses led to withdrawals toward the Vistula line and concentrated defence of Warsaw. The entry of the Red Army from the east accelerated strategic collapse as Polish forces attempted link-up with the Romanian Bridgehead and evacuation of the government and military assets to Romania and Hungary.

Polish Military Organization and Key Battles

Poland organized its forces into armies including the Army Kraków, Army Łódź, Army Poznań, and Army Pomorze, commanded by officers like Edward Rydz-Śmigły and corps leaders such as Tadeusz Kutrzeba. The Polish Air Force engaged the Luftwaffe from bases including Okęcie and improvised fields, while the Polish Navy executed operations from Hel and ships like ORP Błyskawica conducted sorties. Key engagements included the Battle of Bzura, a major counterattack led by Tadeusz Kutrzeba and Władysław Bortnowski, which delayed German plans, and the siege of Warsaw, where defenders under Walerian Czuma and Stefan Starzyński resisted until capitulation. Armoured clashes showcased units like 1st Panzer Division opposing Polish cavalry brigades and improvised armoured trains.

Civilian Impact and Resistance

The invasion produced mass displacement from regions such as Silesia and Podlasie, aerial bombing of cities including Wieluń and systematic repression in occupied areas administered by entities like the Reichsgau Danzig-West Prussia and Generalbezirk Galizien later on. Atrocities and executions by SS units and elements of the NKVD created immediate humanitarian crises that would be followed by policies including deportations to the Soviet Union and expulsions under Intelligenzaktion. Civil society responded with the formation of clandestine structures such as the Union of Armed Struggle and later Armia Krajowa, local partisan groups, and continued underground press and intelligence networks that linked to governments-in-exile in London.

Aftermath and Military Assessment

The campaign ended with the occupation and partition of Poland under the German–Soviet boundary and friendship treaty, the flight of political and military leadership to France and United Kingdom, and the reconstitution of Polish armed forces abroad leading to formations in France and later the Polish Armed Forces in the West. Military assessments highlight the effectiveness of Blitzkrieg techniques by Wehrmacht motorized and combined-arms units, Polish shortcomings in armoured warfare concentration and strategic reserves, and the decisive strategic impact of the Molotov–Ribbentrop Pact. The defence nonetheless provided crucial time for Allied mobilization and established traditions of Polish resistance that influenced subsequent operations such as the 1944 Warsaw Uprising and Polish contributions to campaigns including Battle of Monte Cassino.

Category:Battles of World War II Category:Military history of Poland