In the 14th and early 15th centuries, three more members of the House of Luxembourg reigned as Holy Roman Emperors and Bohemian Kings: John's descendants Charles IV, Sigismund (who also was King of Hungary and Croatia), and Wenceslaus IV. Charles IV created the long-lasting Golden Bull of 1356, a decree which fixed important aspects of the constitutional structure of the Empire. Luxembourg remained an independent fief (county) of the Holy Roman Empire, and in 1354, Charles IV elevated it to the status of a duchy with his half-brother Wenceslaus I becoming the first Duke of Luxembourg. While his kin were occupied ruling and expanding their power within the Holy Roman Empire and elsewhere, Wenceslaus, annexed the County of Chiny in 1364, and with it, the territories of the new Duchy of Luxembourg reached its greatest extent.