Task: Question Generation
Input (English): Passage: Brandenburg-Prussia's claims in Silesia were based, in part, on a 1537 inheritance treaty between the Silesian duke Frederick II of Legnica and the Hohenzollern Prince-Elector Joachim II Hector of Brandenburg, whereby the Silesian duchies of Liegnitz, Wohlau and Brieg were to pass to the Electorate of Brandenburg if the Silesian Piasts should become extinct. At the time, the Habsburg King Ferdinand I of Bohemia  immediately rejected the agreement; nevertheless, in 1675 the "Great Elector" Frederick William of Brandenburg laid claim to the Silesian principalities when, with the death of Duke George William of Liegnitz, the Piast line ended. In 1603, Hohenzollern Elector Joachim III Frederick of Brandenburg also inherited the Silesian Duchy of Jägerndorf from his cousin, Margrave George Frederick of Brandenburg-Ansbach. After the Bohemian Revolt and the outbreak of the Thirty Years' War, however, the Catholic Holy Roman Emperor Ferdinand II confiscated the possessions of the Protestant Hohenzollerns in his Bohemian lands in 1621 after winning the Battle of White Mountain. The Electors of Brandenburg continued, nevertheless, to assert themselves as the legitimate rulers of Jägerndorf. Brandenburg, however, was unable to enforce these dynastic territorial claims. In 1685, when Austria was engaged in the Great Turkish War, Emperor Leopold I gave Elector Frederick William immediate control of the Silesian exclave of Schwiebus in return for military support against the Turks and the surrender of the outstanding Hohenzollern claims in Silesia. However, after the accession of the Elector's son and successor, Frederick III of Brandenburg, the Emperor took back control of Schwiebus in 1694, asserting that the territory had only been personally assigned to the late Frederick William for life. Furious, Frederick III in turn reasserted the old Hohenzollern claims to Jägerndorf and the Silesian Piast heritage.
Output (English): How many years after the Battle of White Mountain was won did the Emperor take back control of Schwiebus?