Germany and the Soviet Union signed a non-aggression pact in Moscow, secretly agreeing to divide Eastern Europe and clearing the path for Hitler's invasion of Poland.

German forces stormed across the Polish border at dawn, and a staged raid on a radio station gave Hitler his pretext for war.

Britain and France declare war on Nazi Germany after its invasion of Poland, formally beginning the Second World War in Europe.

Igor Sikorsky piloted his VS-300, the first practical single-rotor helicopter, on its inaugural tethered flight in Connecticut, launching the modern helicopter industry.

Atlanta hosted the glittering premiere of Gone With the Wind, a three-day-long segregated celebration for a film that became Hollywood's highest-grossing epic.