Following the defeats Prussia suffered in the 30 Years' War Frederick William, Elector of Brandenburg, set up the General War Commissariat to oversee the army, as well as to levy taxes necessary to support the army. It soon became a bureaucratic machine for civil government as well. Frederick William used it to govern the state. Many members were landed aristocracy known as Junkers, who served in the army as well. The commissariats helped to centralize power.