Joachim III Frederick, Elector of Brandenburg (1546–1608), Prince-elector of the Margraviate of Brandenburg
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Joachim Frederick of Brieg (1550–1602), Duke of Oława, Wołów, Brzeg, and Legnica
Frederick the Great | Frederick | Frederick II | Frederick II, Holy Roman Emperor | Frederick Russell Burnham | Frederick Roberts, 1st Earl Roberts | Frederick Law Olmsted | Joachim Murat | Frederick I, Holy Roman Emperor | Frederick Forsyth | Frederick Douglass | Frederick, Maryland | Prince Frederick, Duke of York and Albany | Frederick III | Frederick I | Frederick Delius | Frederick William III of Prussia | John Frederick II, Duke of Saxony | Frederick III, German Emperor | Frederick William IV of Prussia | Frederick Schomberg, 1st Duke of Schomberg | Frederick I, Margrave of Brandenburg-Ansbach | Frederick III, Holy Roman Emperor | Joachim | Frederick, Prince of Wales | Frederick Funston | Frederick Ashton | John Frederick II | Frederick Wiseman | Frederick Marryat |
Following King Sigismund III's Prussian regency contract (1605) with Joachim Frederick of Brandenburg and his Prussian enfeoffment contract (Treaty of Warsaw, 1611) with John Sigismund of Brandenburg these two rulers of Ducal Prussia guaranteed free practice of Catholic religion in prevailingly Lutheran Prussia.