Posen–West Prussia

Frontier March of Posen-West Prussia
Grenzmark Posen-Westpreußen (German)
Province of Prussia
1920/1922–1938
Coat of arms

Posen-West Prussia (red) within the
Free State of Prussia (blue).

CapitalSchneidemühl
Area 
 1925
7,695 km2 (2,971 sq mi)
Population 
 1925
332,400
History 
 Created from Posen and
West Prussia
1 July 1920/1922
 Ruled by Brandenburg
1934
 Divided between
Brandenburg, Pomerania
and Silesia
1 October 1938
Preceded by
Succeeded by
Province of Posen
West Prussia
Province of Pomerania (1815–1945)
Province of Brandenburg
Province of Silesia
Today part of

The Frontier March of Posen–West Prussia (German: Grenzmark Posen-Westpreußen; Polish: Marchia Graniczna Poznańsko-Zachodniopruska) was a province of Prussia from 1920/1922 to 1938, covering most of lands of historical Greater Poland that were not included in the Second Polish Republic. Posen–West Prussia was established in 1922 as a province of the Free State of Prussia within Weimar Germany, formed from merging three remaining non-contiguous territories of Posen and West Prussia, which had lost the majority of their territory to the Second Polish Republic following the Greater Poland Uprising. From 1934, Posen–West Prussia was de facto ruled by Brandenburg until it was dissolved by Nazi Germany, effective 1 October 1938 and its territory divided between the provinces of Pomerania, Brandenburg and Silesia. Schneidemühl (present-day Piła) was the provincial capital. Today, lands of the province are entirely contained within Poland.