 In Prussia, during the Drang nach Osten and the Northern Crusades of the twelfth and thirteenth centuries, encastellation was the result of the Margraves of Brandenburg and the Teutonic Knights, who, among others, conquered the land from the pagan Prussians.The construction of castles to control territories occurred at a late point in the development of the castle and these fortresses were large and complex.They were called "Ordensburgen" and they served as headquarters and training grounds for initiates into the knightly orders.