a reasonable chance with the electors. At this meeting, the Cardinal began negotiating with Wilhelm the fees and titles for him and his brother if they worked for French interests. The Cardinal instructed his lead negotiator in the Empire, Hugues de Lionne, to continue negotiating with the brothers for their support, indicating that the king would pay them eighteen thousand livres for ongoing dedicated work, regardless of the result of the election of the Emperor. Wilhelm insisted on a document spelling out the benefits offered, as he was concerned the French might leave him out to dry after he showed himself too strongly opposed to the Habsburgs. On 4 June 1658, Lionne, Franz, and Wilhelm signed an agreement detailing French support for the counts should they continue to work "for all the plans and interests of His Majesty in Germany". Following the coronation of Leopold I, Wilhelm and Franz contributed significantly to the establishment of the League of the Rhine in August 1658. This was supported and joined by the French as a further check against the new Habsburg Emperor. The Habsburgs tried to offer the brothers prizes and titles if they would halt the League's formation, but they refused. International negotiations In 1659, Cardinal Mazarin asked Maximilian and Johann Philipp von Schönborn, the Elector of Mainz, to oversee negotiations to end the Franco-Spanish War. Maximilian thereafter sent Wilhelm regularly to the French court, to negotiations and ultimately to the signing of the Treaty of the Pyrenees. In 1661, Wilhelm spent months in Paris conveying the suit of Charles IV, Duke of Lorraine, who wished to marry Anne Marie Louise d'Orléans, Duchess of Montpensier. While she rejected the offer, she did enjoy spending time with Wilhelm, admiring his intelligence and his knowledge of foreign affairs. In 1664, Leopold elevated the territory of Fürstenberg-Heligenberg from a county to a principality, and also extended the title of Prince to Franz and Wilhelm, though their brother ruled the territory. This was done to try and draw the brothers closer to Habsburg Austria, but did not appear to change much. As the representative from Cologne, Wilhelm drove the negotiations in 1665 and 1666 to end the involvement of Bernhard von Galen, the Bishop of Münster, in the Second Anglo-Dutch War so that they would not overly restrict the authority of the Bishop of Münster to wage war in the future. When Philip IV of