At 4:45 a.m., the German battleship Schleswig-Holstein opened fire on Polish positions near Danzig while more than a million Wehrmacht troops crossed the frontier. The invasion, launched days after the staged Gleiwitz incident, prompted Britain and France to declare war on Germany two days later, igniting the Second World War.
The attack began not with tanks but with a lie. On the night of August 31, SS operatives dressed in Polish uniforms staged a fake raid on a German radio transmitter at Gleiwitz, leaving behind a drugged concentration camp prisoner shot dead as 'evidence' of Polish aggression. Hitler cited this fabricated provocation as justification for war he had already ordered.
At dawn, over 60 German divisions poured across Poland's borders from three directions while the Luftwaffe struck airfields, railways, and cities in the first large-scale demonstration of blitzkrieg warfare — combining fast-moving armor with close air support to shatter Polish defenses before they could mobilize.
Poland's cavalry brigades, still partly organized along World War I lines, fought with desperate courage against tanks and dive bombers, giving rise to the enduring but exaggerated myth of Polish lancers charging German panzers. Warsaw held out until September 28, but by early October Poland had been carved up between Germany and the Soviet Union under the terms of the Molotov-Ribbentrop Pact, and Europe had entered six years of catastrophic war.