West Prussia (German: Westpreußen; Kashubian: Zôpadné Prësë; Polish: Prusy Zachodnie) was a province of the Kingdom of Prussia from 1773-1824 and 1878-1919/20 which was created out of the earlier Polish province of Royal Prussia. In February 1920, Germany (after it had been defeated in 1918) handed over West Prussia's central parts to become the so-called Polish Corridor (i.e. Pomeranian Voivodeship) and the Free City of Danzig, while the parts remaining with the German Weimar Republic became the new Posen-West Prussia or were joined to the Province of East Prussia as Regierungsbezirk West Prussia. The territory was included within Reichsgau Danzig-West Prussia from 1939-45, after which it became part of Poland.
Map of Prussia; West Prussia (WP) in the eastern part of Prussia is highlighted in light blue
Map of West Prussia