This day in history, August 31, 1939, Nazi leader Adolf Hitler signs an order to attack Poland despite threats of intervention from both France and Britain. German forces then moved to the frontier to ready their attack.
That evening, Nazi S.S. troops wearing Polish uniforms took part in a phony invasion of Germany, damaging several minor installations on the German side of the border. A few German prisoners in Polish uniforms were killed and left behind to serve as evidence of the alleged Polish attack, which Nazi propagandists publicized as an act of aggression towards Germany.
Early the next morning around 4:45 am, 58 German army divisions invaded Poland all along the 1,750-mile frontier. Hitler expected appeasement from Britain and France since they had given the Sudetenland away to Germany in 1938 with their signing of the Munich Pact.
Neither Britain or France would allow Hitler’s violation of European borders, and Germany was presented with an ultimatum to cease military operations. They were given the choice to withdraw by September 3 or face war with several western democracies. Germany ignored the ultimatum.
At 11:15 a.m. on September 3, only a few minutes after the expiration of the British ultimatum, Prime Minister Neville Chamberlain appeared on national radio announcing that Britain was at war with Germany. Australia, New Zealand, South Africa, Canada and India shortly followed suit. Later in the afternoon of September 3, the French ultimatum expired, and at 5:00 p.m. France declared war on Germany and World War II in Europe began.