The Outbreak of War: Danzig, the Nazi-Soviet Pact, and the Invasion of Poland

The Free City of Danzig and the Polish Corridor both originated in the territorial arrangements of Versailles. Germany demanded the reincorporation of Danzig, whose population was predominantly German, along with an extraterritorial route across the Polish Corridor connecting Germany to East Prussia. Poland flatly refused any concession that would compromise its access to the Baltic Sea, and German pressure escalated through 1939 as Germany renounced its 1934 non-aggression pact with Poland outright, prompting Britain and France to extend formal military guarantees to Warsaw.