The War of the Jülich Succession  was a military conflict over the right of succession to the United Duchies of Jülich-Cleves-Berg. It lasted between 10 June 1609 and 24 October 1610, resuming in May 1614 and finally ending in 13 October 1614. The first round of the conflict pitted Catholic Archduke Leopold V against the combined forces of the Protestant Margraviate of Brandenburg and Palatinate-Neuburg, ending in the former's military defeat. The representatives of the Brandenburg and Neuburg later entered into a direct conflict after their religious conversion to Calvinism and Catholicism respectively. The conflict was further complicated by the involvement of Spain and the Netherlands making it part of the Eighty Years' War. It was finally settled by the Treaty of Xanten, provisions of which favored Spain.. Which religion did the representatives of the Brandenburg and Neuburg later convert to, Calvinism or Catholicism?