The so-called United Duchies of Jülich-Cleves-Berg was a territory in the Holy Roman Empire between 1521 and 1666, formed from the personal union of the duchies of Jülich, Cleves and Berg. The name was resurrected after the Congress of Vienna for province of Jülich-Cleves-Berg of the Kingdom of Prussia between 1815 and 1822. Its territory is today split between the German state of North Rhine-Westphalia and the Dutch province of Gelderland. History The United Duchies of Jülich-Cleves-Berg was a combination of states of the Holy Roman Empire. The duchies of Jülich and Berg united in 1423. Nearly a century later, in 1521, these two duchies, along with the county of Ravensberg, fell extinct, with only the last duke's daughter Maria von Geldern left to inherit; under Salic law, women could only hold property through a husband or guardian, so the territories passed to her husband—and distant relative—John III, Duke of Cleves and Mark as a result of their strategic marriage in 1509. These united duchies controlled most of the present-day North Rhine-Westphalia that was not within the ecclesiastical territories of Electoral Cologne and Münster. Only a century after John III's marriage, however, the united ducal line fell extinct, prompting a war over the succession to the territories. The grandson of John III — Duke John-William — died without issue in 1609. His inheritance was claimed by the heirs of his two eldest sisters. Whilst the dukes, inspired by the humanism of Desiderius Erasmus, had managed to bear a "" between the confessional disputes ensuing from the Protestant Reformation, the heirs of the last duke's two eldest sisters were on opposite sides of the divide. The situation was further complicated by acquisitive desires of Emperor Rudolph II and the Wettin dukes of Saxony—the former particularly worrying to Henry IV of France and the Dutch Republic, who feared any strengthening of the Habsburg Netherlands. The Lutheran Anna of Prussia was married to John Sigismund, Elector of Brandenburg, whereas Roman Catholic Anna of Cleves was married to Philip Louis, Count Palatine of Neuburg. As a result, after the War of the Jülich Succession (one of the precursors to the Thirty Years' War) was settled at Xanten, the Protestant territories (Cleves, Mark and Ravensburg) passed to Brandenburg-Prussia with the Catholic lands (Jülich and Berg) being awarded to the Palatinate-Neuburg. Years of being trampled by armies had destroyed much of the lands' wealth that had