Topic summary
Duchy of Prussia
Poland
Russia
The Duchy of Prussia (German: Herzogtum Preußen, Polish: Księstwo Pruskie, Lithuanian: Prūsijos kunigaikštystė) or Ducal Prussia (German: Herzogliches Preußen; Polish: Prusy Książęce) was a duchy in the region of Prussia established as a result of secularization of the Monastic Prussia, the territory that remained under the control of the State of the Teutonic Order until the Protestant Reformation in 1525.