Definition
September 1939 denotes the ninth month of the year 1939 in the Gregorian calendar, internationally recognized as the period during which World War II began with the German invasion of Poland and the subsequent declarations of war by Britain and France.
Overview
The month opened with escalating diplomatic tensions in Europe. On 1 September 1939, Nazi Germany launched a coordinated attack on Poland, employing blitzkrieg tactics that combined infantry, armor, and air power. In response, the United Kingdom and France, honoring mutual defense guarantees to Poland, issued ultimatums demanding German withdrawal. When the demands were unmet, Britain declared war on Germany on 3 September, followed by France a few hours later. These declarations marked the formal commencement of the Second World War in Europe. Throughout September, additional military actions occurred, including Soviet incursions into eastern Poland on 17 September, following the Molotov–Ribbentrop Pact’s secret protocol dividing Polish territories between Germany and the USSR. The month concluded with the rapid collapse of Polish resistance and the occupation of the Polish state by German and Soviet forces.
Etymology/Origin
The term “September 1939” combines the name of the ninth month of the Gregorian calendar, derived from the Latin septem (“seven”) reflecting its position in the early Roman calendar, with the ordinal year 1939, counting from the traditionally estimated birth of Jesus Christ. The compound is employed as a chronological reference rather than a lexical concept.
Characteristics
- Military: Initiation of large‑scale mechanized warfare (blitzkrieg); rapid territorial gains by Germany; subsequent Soviet invasion of eastern Poland.
- Political: Formal declarations of war by the United Kingdom (3 September) and France (3 September); activation of the Anglo‑Polish military alliance; dissolution of the policy of appeasement.
- Diplomatic: Enforcement of the secret protocols of the Molotov–Ribbentrop Pact; breakdown of the League of Nations’ effectiveness.
- Social: Massive civilian displacement; onset of wartime censorship and propaganda; beginning of persecution of Polish Jews and other minority groups under German occupation.
- Economic: Mobilization of national economies for war production; disruption of trade routes in Central and Eastern Europe.
Related Topics
- World War II (1939–1945)
- Invasion of Poland (1939)
- Molotov–Ribbentrop Pact (1939)
- Blitzkrieg warfare
- United Kingdom–Poland relations
- France–Poland military alliance
- Soviet invasion of eastern Poland (1939)
- International response to the outbreak of World War II.