Frederick William I
Charles X Gustav granted Frederick William I full souvereignity in the Duchy of Prussia and Ermland (Ermeland, Warmia). For his Prussian possessions, Frederick William I was elevated from the status of a duke to a "princeps summus &amp; Suverenus". Article III specifies that this applies also to Frederick William I's successors, who likewise would have the status of "principes summi &amp; absoluti Suverenii".