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Germany's invasion of Poland on September 1, 1939, using swift "Blitzkrieg" tactics, triggered World War II, with Britain and France declaring war. This was followed by a Soviet invasion from the east on September 17, as pre-planned in the secret Molotov-Ribbentrop Pact, leading to Poland's division and conquest by both totalitarian powers, ending organized Polish resistance by early October. The invasion introduced new mobile warfare, rapid destruction of Polish defenses, and immediate Nazi -
Great Britain and France declared war on Nazi Germany, two days after Hitler’s invasion of Poland, marking the official beginning of World War II in Europe. Following the failure of an ultimatum for Germany to withdraw from Poland, British Prime Minister Neville Chamberlain announced the declaration on radio -
On May 10, 1940, Nazi Germany launched a rapid, overwhelming blitzkrieg invasion of Belgium, Luxembourg, and the Netherlands, concurrently invading France to initiate the Battle of France. Utilizing armored, aerial, and airborne forces, Germany overcame low-country resistance in days before forcing France to surrender by June 22, 1940. -
rescued over 338,000 Allied troops trapped by German forces in Northern France. A makeshift fleet of nearly 1,000 naval and civilian vessels ("Little Ships") saved the British Expeditionary Force (BEF) from destruction. This "miracle" of survival allowed Britain to continue fighting, turning a potential military catastrophe into a morale-boosting symbol of resistance -
the Royal Air Force (RAF) defended the UK from large-scale Nazi German Luftwaffe attacks, preventing Hitler's planned Operation Sea Lion invasion after France fell. Germany sought air superiority to facilitate invasion but failed, as Britain's use of radar (the Dowding System), superior fighter technology (Spitfires, Hurricanes), and strategic defense outlasted the Luftwaffe's assault, marking Britain's first major victory of WWII and a turning -
The Selective Training and Service Act of 1940 was the U.S.'s first peacetime draft, signed by President Roosevelt, requiring men aged 21-36 to register for potential military service as the nation prepared for World War II; it established the Selective Service System, which conscripted millions of men during WWII and subsequent conflicts like the Korean War, though the draft ended in 1973, with registration for men aged 18-25 remaining active today for future national emergencies -
allowed the U.S. to supply war materials—ammunition, tanks, airplanes, and food—to Allied nations (primarily Great Britain, the Soviet Union, and China) without immediate payment, effectively ending U.S. neutrality. This legislation, which ran through 1945, was critical for the Allied war effort.