Hitler began his plan with a nonaggression pact with Poland in January 1934.
This pact was contravened five and a half years later – Hitler had just been buying time. The pact was unpopular with his supporters, who resented the Versailles Treaty's giving former German provinces to Poland. Hitler, however, saw the nonaggression pact as a way to prevent a French-Polish military alliance against Germany before the Wehrmacht had rearmed.
In the second half of the 1930s, France and Britain pursued a policy of appeasement toward Germany. Public opinion (especially in Britain) was sympathetic to revising some territorial provisions of the Versailles treaty, and neither Britain nor France in 1938 was militarily prepared to fight the Nazis. So Britain and France acquiesced to:
- German rearmament (1935-1937).
- Remilitarization of the Rhineland (1936).
- Annexation of Austria (the Anschluss, March 1938).
- Invasion of the Sudetenland and breakup of the Czechoslovak state (March 1939) in violation of Anglo-French guarantees of the integrity of rump Czechoslovakia in what is called the Munich agreement.
One week after the surprise pact with Stalin, at 5:11 a.m., Hitler issued an order for the Wehrmacht to invade Poland, claiming that the Poles were preparing to invade Germany. In fact, the Wehrmacht was massing on the German side of Poland's western border and the Poles were simply moving their army to defend this border.
Britain and France declared war within two days, but it was too late. The German army launched its Blitzkrieg, its "lightning war." From East Prussia and Germany in the north and Silesia and Slovakia in the south, more than 2,000 German tanks,covered by more than 1,000 planes, broke through Polish defenses along the border. Within six days they took Krakow and within ten they were outside Warsaw. By early October, Poland had fallen. World War II was on.