Largely sympathetic to the Lithuanian desire for autonomy and determined to create a strong, central royal power, Casimir clashed with the Polish magnates, large landowners who had dominated the earlier Jagiellon reigns, by granting extensive and exclusive rights and privileges to the gentry in order to gain their political and financial support for his active foreign policy. As a result, Casimir was able not only to engage successfully in the Thirteen Years’ War (1454–66) against the Teutonic Knights, by which he acquired a large portion of their territory, but also to place his son Władysław on the thrones of Bohemia (as Vladislav II; 1471) and Hungary (as Ulászló II; 1490) and to fight the Turks (1485–89), who had disrupted his kingdom’s trade by seizing control of the mouths of the Dniester and Danube rivers.