The rapid spread of the Lutheran and Calvinist doctrines following the Protestant Reformation was met by a period of Roman Catholic resurgence known as Counter-Reformation. Such interdenominational conflicts as the Cologne War and Strasbourg Bishops' War prompted creation of the Catholic League and the Protestant Union, with the intention of safeguarding the interests of the Holy Roman Empire's Catholic and Protestant nobility respectively. The aforementioned alliances entered their first conflict in 1609, when a succession crisis in the United Duchies of Jülich-Cleves-Berg sparked the War of the Jülich Succession. The territories in question covered an area of 14,000 km², having both geopolitical importance due to their proximity to the Spanish Road and a booming economy which was fueled by refugees fleeing the lands ravaged by the Eighty Years' War. The mentally ill Duke Johann Wilhelm died on 25 March 1609, leaving no heirs to succeed him. Emperor Rudolf II had claims to the duchies stemming from intermarriage. However, he was unable to openly declare his intentions without compromising his perceived neutrality. A total of six other claimants appeared, with rulers of the Margraviate of Brandenburg and Duchy of Palatinate-Neuburg having the only credible claims through their marriage to Johann Wilhelm's aunts. On 2 April, a regency was established, including the duke's wife Antoinette of Lorraine, the privy councilors, and an imperial commissioner. On 24 May, Rudolf II announced that the Aulic Council was to provide a definite verdict within four weeks.