Germany’s interest ⇒ in Polish corridor and Danzig ⇒ was due to large population of Germans and desire for a transportation line across Polish corridor ⇒ that separated Germany from the province of East Prussia.
Since April 1939 ⇒ Germany ⇒ had taken action to demand Polish corridor and Danzig. However ⇒ Polish leaders ⇒ rejected these demands. They did not trust Hitler ⇒ and were concerned about a German invasion Tensions → between Poland and Germany → escalated → as talks and negotiations between them broke down.
1 September 1939 ⇒ certain that there would be no opposition from the USSR ⇒ because of the Pact ⇒ Germany invaded Poland. However ⇒ Hitler miscalculated that Britian and France would not go to war over Poland. 3 September 1939 ⇒ Britain and France⇒ declared war on Germany. → World war II had begun.