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Major Events of September 1939: Key Historical Moments from the Month

Each month is marked by defining moments that shape the course of history. Whether through political shifts, cultural movements, or world-changing events, these periods leave a lasting impression. Dive into the most important events from September 1939 and discover how they influenced the world both then and now.

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Major Events of September 1939: Key Historical Moments from the Month

  • 01 Sep 1939 Nazi Germany Invades Poland, Starting World War II: On September 1, 1939, Nazi Germany launched a comprehensive invasion of Poland from multiple directions, marking the official beginning of World War II in Europe. German forces attacked from three primary directions: Army Group South under Colonel General Gerd von Rundstedt from the west over Silesia, General Johannes Blaskowitz's 8th Army advancing toward Lodz, General Wilhelm List's 14th Army moving to Krakow, and General Walter von Reichenau's forces spearheading an assault toward Warsaw.
  • 02 Sep 1939 Luftwaffe Decimates Polish Air Force: On September 2, 1939, the German Luftwaffe effectively destroys the Polish air force during the second day of the invasion, critically undermining Poland's defensive capabilities and accelerating the country's military defeat.
  • 03 Sep 1939 Britain Declares War on Germany: At 1110 hours London time, British Prime Minister Neville Chamberlain officially declares that the United Kingdom is at war with Germany, marking the formal start of World War II in Western Europe.
  • 04 Sep 1939 Poland-France Mutual Assistance Protocol Signed: A strategic Protocol of Mutual Assistance is signed between Poland and France, establishing military cooperation in response to German aggression during the early stages of World War II.
  • 05 Sep 1939 United States Declares Neutrality in World War II: The United States formally declares its neutrality in the escalating global conflict, marking an initial stance of non-intervention at the war's outbreak.
  • 06 Sep 1939 German Invasion of Poland: German forces capture Cracow, Poland, as part of the broader invasion that marks the beginning of World War II, signaling the aggressive expansion of Nazi Germany into Eastern Europe.
  • 07 Sep 1939 Westerplatte Fortress Surrenders in World War II: At 1100 hours, Polish defenders of the Westerplatte Fortress in Danzig Harbor (now Gdańsk, Poland) surrender after a heroic multi-day defense against German invasion, marking a significant early moment in World War II.
  • 08 Sep 1939 German Invasion of Warsaw Begins: At 0515 hours, the first German troops enter the Polish capital Warsaw, marking a critical moment in the early stages of World War II's invasion of Poland.
  • 09 Sep 1939 Battle of the Bzura Begins: Polish Poznań Army, led by General Kutrzeba, launched the Battle of the Bzura, the largest and most organized Polish counter-offensive of the 1939 campaign. Initially successful, the Polish forces temporarily forced German units to retreat, but were ultimately overwhelmed by German mechanized units and Luftwaffe air superiority.
  • 10 Sep 1939 Canada Declares War on Germany: At 1:10 PM in Ottawa, Canada, the Governor-General of Canada, Lord Tweedsmuir, officially announces that the Canadian Parliament has declared war on Germany, effective from the start of the day. This declaration marks Canada's formal entry into World War II, demonstrating the country's commitment to supporting the Allied powers against Nazi aggression.
  • 11 Sep 1939 British Government Rejects Peace with Hitler: The British Ministry of Information officially declares that the British Government would not negotiate or conclude peace with any German government led by Adolf Hitler, signaling a firm stance against Nazi leadership during the early stages of World War II.
  • 12 Sep 1939 Anglo-French War Council Delays Military Action: The Anglo-French Supreme War Council strategically decided to postpone military operations against Germany on September 12, 1939, likely to assess military readiness and coordinate allied strategies in the early days of World War II.
  • 13 Sep 1939 Nazi Germany Annexes Free City of Danzig: Germany annexes the Free City of Danzig (modern Gdańsk, Poland), forcibly overwhelming Polish resistance at the city's Post Office, marking a significant territorial expansion and escalation of hostilities in the early stages of World War II.
  • 14 Sep 1939 German Forces Encircle Warsaw: German military troops successfully complete the strategic encirclement of Warsaw, Poland, effectively trapping Polish defenders and isolating the city from potential reinforcements.
  • 15 Sep 1939 German Wehrmacht Besieges Warsaw: During World War II, various elements of the German Wehrmacht surrounded Warsaw and demanded its surrender. The Polish forces categorically refused, marking the beginning of an intense siege that would become a significant moment in the early stages of the war.
  • 16 Sep 1939 Border War Between Soviet Union and Japan Ends: A ceasefire is declared in the undeclared Border War between the Soviet Union (with Mongolian allies) and Japan, temporarily reducing tensions in the region.
  • 17 Sep 1939 Soviet Invasion of Eastern Poland: At 0400 hours, Soviet Russian armies crossed the entire eastern frontier of Poland, claiming the Polish State no longer exists. They justified their invasion by stating they were 'protecting their own interests and the White Russian and Ukrainian minorities'.
  • 18 Sep 1939 German-Soviet Invasion and Partition of Poland: Russian and German military forces converge in Poland, meeting at strategic locations like Vilna and Brest-Litovsk. A joint German-Soviet military commission convenes to draft plans for the systematic partition of Polish territory, marking a critical moment in the early stages of World War II.
  • 19 Sep 1939 Hitler's Speech on Poland's Fate: Adolf Hitler delivers a pivotal speech in Danzig, declaring that Poland's future will be determined by Germany and Russia. He claims to have accepted the western border and emphasizes no war aims against Britain or France, signaling the early stages of the Nazi invasion of Poland.
  • 20 Sep 1939 German Army Declares Polish Campaign Complete: German Colonel General Walther von Brauchitsch announces the completion of military operations in Poland. In just twenty days of warfare, German forces have occupied approximately 100,000 square miles of territory and captured 400,000 Polish prisoners, marking a swift and decisive conquest.
  • 21 Sep 1939 Heydrich's Meeting on Jewish 'Final Solution': Reinhard Heydrich convened a critical meeting in Berlin to discuss the Nazi plan for the systematic removal and persecution of Jewish populations, marking an early stage of the Holocaust.
  • 22 Sep 1939 Soviet Forces Occupy Polish Cities: Soviet military forces occupied the strategically important Polish cities of Brest-Litovsk and Bialystok as part of the coordinated invasion of Poland by Nazi Germany and the Soviet Union, marking a critical moment in the early stages of World War II.
  • 23 Sep 1939 Cookie Lavagetto's Historic Baseball Performance: On September 23, 1939, Brooklyn Dodgers player Cookie Lavagetto achieved an extraordinary batting performance, going 6 for 6 at the plate during a remarkable game against the Philadelphia Phillies. The Dodgers overwhelmingly dominated the game, securing a stunning 22-4 victory and recording an impressive 27 total hits.
  • 24 Sep 1939 Massive German Bombing of Warsaw: On September 24, 1939, a massive aerial assault was launched by Germany, with 1,150 aircraft bombing the city of Warsaw during the early stages of World War II.
  • 25 Sep 1939 Warsaw Falls to Nazi Germany: On September 25, 1939, the city of Warsaw was captured by Nazi German forces, representing a critical moment in the invasion of Poland and signaling the imminent collapse of Polish resistance during the initial phase of World War II.
  • 26 Sep 1939 First German Aircraft Shot Down by British Forces in WWII: On September 26, 1939, the Luftwaffe attempted to attack the British Home Fleet between Scotland and the Skaggerak. During this engagement, a Dornier Do 18 was shot down by a Blackburn Skua fighter from the aircraft carrier HMS Ark Royal, marking the first German aircraft destroyed by British forces in World War II.
  • 27 Sep 1939 Warsaw Falls to German Forces: At 2010 hours, Warsaw, Poland officially surrenders to German troops after a grueling 21-day siege during the opening stages of World War II. The city's resistance was heroic but ultimately overwhelmed by superior German military force and aerial bombardment.
  • 28 Sep 1939 German-Soviet Treaty of Frontier Regulation and Friendship: Nazi Germany and the Soviet Union signed a treaty in Leningrad, finalizing the partition of Poland. The agreement, negotiated by German Foreign Minister Joachim von Ribbentrop and Soviet Commissar for Foreign Affairs Vyacheslav Molotov, transferred control of Lithuania to the Soviet Union and redrew territorial boundaries in Eastern Europe.
  • 29 Sep 1939 Invasion of Poland by Nazi Germany and Soviet Union: On September 29, 1939, Nazi Germany and the Soviet Union launched a coordinated invasion of Poland, effectively partitioning the country between them. This event marked the beginning of World War II in Europe, with both totalitarian powers executing a pre-planned strategy to eliminate Poland's sovereignty. The invasion was a direct result of the secret Molotov-Ribbentrop Pact signed in August 1939, which divided Eastern European territories between Germany and the Soviet Union.
  • 30 Sep 1939 Nazi-Soviet Partition of Poland: Germany and Soviet Russia agree to partition Poland, a devastating diplomatic agreement that effectively divides and conquers Polish territory at the start of World War II.