and children, Cathar and Catholic alike, decimating the number of practising Cathars and diminishing the region's distinct culture. The conflict took on a political flavor, directed not only against the heretics, but also the nobility of Toulouse and vassals of the Crown of Aragon, and finally brought the region firmly under the control of the king of France. King Peter II of Aragon, Count of Barcelona, was directly involved in the conflict, and was killed in the course of the Battle of Muret in 1213. The conflict largely ended with the Treaty of Paris of 1229, in which the integration of the Occitan territory in the French crown was agreed upon. Pope Innocent III spent a majority of his tenure as Pope (1198–1216) preparing for a great crusade on the Holy Land. His first attempt was the Fourth Crusade (1202–1204) which he decreed by the papal bull Post miserabile in 1198. Unlike past popes, Innocent III displayed interest in leading the crusade himself, rather than simply instigating it and allowing secular leaders to organize the expedition according to their own aspirations. Innocent III's first order of business in preaching the crusade was to send missionaries to every Catholic state to endorse the campaign. He sent Peter of Capua to the kings of France and England with specific instructions to convince them to settle their differences, resulting in a truce of five years between the two nations, beginning in 1199. The intent of the truce was not to allow the two kings to lead the crusade, but rather to free their resources to assist the Crusade. For the army's leadership, Innocent aimed his pleas at the knights and nobles of Europe, succeeding in France, where many lords answered the pope's call, including the army's two eventual leaders, Theobald of Champagne and Boniface, marquis of Montferrat. The pope's calls to action were not received with as much enthusiasm in England or Germany, and the expedition became mainly a French affair. The Fourth Crusade was an expensive endeavor. Innocent III chose to raise funds with a new approach: requiring all clergy to donate one fortieth of their income. This marked the first time a pope ever imposed a direct tax on the clergy. He faced many difficulties in collecting this tax, including corrupt tax collectors and disregard in England. He also sent envoys to King John of England and King Philip of France,