At first, afraid of confronting a resurgent Germany, Western democracies watched its aggression with gritted teeth. But when German troops invaded Poland on 1 September, 1939, the worst war the world has ever known was unleashed.
Typically, the Nazis surprised all their enemies early on, scoring a series of shockingly quick military victories on every front. But Germany had over-extended itself badly and when its main foes regained their bearings, they finally proceeded in pincer movements to crush Germany militarily. In 1933, Hitler had claimed, "Give me 10 years, and you won't recognize Germany". This was one promise that was clearly kept - though certainly not in the way Hitler had intended it.
Frankfurt's historic old town lay in rubble at the end of World War II