In the mid-sixteenth century, King Philip II of Spain entered into tense negotiations with Rome over the fate of the bula de la cruzada, a crusading indulgence that had been granted to Iberian monarchs since the Middle Ages. That indulgence had become a means of defraying the cost of war against enemies of the faith. But endemic abuses and concerns about the growing power of Spanish monarchs in ecclesiastical affairs led popes and Tridentine delegates to pursue an end to the cruzada. Philip emerged the victor from this contest and in so doing signaled the co-opting of the medieval crusading tradition by the early modern state. While these developments abetted governmental bureaucratization and centralization in Spain, they also undermined its economic, social, and religious stability, a risk made acceptable by Philip’s own sense of divine mission.