As a follow up to a recent post on the scholarship of retired Cambridge University scholar Jonathan Riley-Smith, I also wanted to highlight (briefly) the work of UNC-Chapel Hill professor Marcus Bull (formerly at the University of Bristol), another influential crusade historian that has made an important argument concerning the religious roots of the crusading movement. With a focus on religious and social history, Bull has (like Riley-Smith) convincingly emphasized the religious appeal of crusading to knights in an important essay and book- both published in 1993.In these works, Bull refuted the long held Erdmann thesis, which argued that the rise of the crusading movement could be explained by papal schemes, inspired by the Peace and Truce of God movements, to simply export violent and rowdy trouble making knights to the Holy Land, thereby restoring peace at home and securing the resurgent papacy’s political power in Europe. Bull takes a different approach as he notes that where the Erdmann approach is most “open to criticism is in its emphasis upon the priorities of a small number of important prelates, canonists and theologians,” to the exclusion of the overwhelming majority of those who actually went on the crusade.
Bull’s key finding, at least in regard to Erdmann, showed that there is no evidence that the response to the First Crusade was most enthusiastic in those areas where the Peace/Truce of God had met with the greatest success. To the contrary, he argued that the pre-existing religious values of knights had to be considered for a full understanding of their response to a crusade. Bull points out that these lords were well aware of their sinfulness. Indeed, their status sometimes required sinful behavior to maintain their positions in life, but they also respected the consequences of their sins and had long sought the remission of their sins through pilgrimage and acts of public benediction. Thus when Pope Urban II preached the First Crusade as an armed pilgrimage, it provided knights with an opportunity to continue in their pilgrimage tradition while performing an act of self-sacrifice to please God.
Among Bull’s key sources for his argument, in contrast to Erdmann who relied extensively on ecclesiastical sources, are the charters of departing crusaders from a wide variety of areas, which Bull argues reveals the appeal of the crusade to its actual participants. These regionally diverse charters reference common elements that suggest the crusades’ appeal to those who drafted them, including the crusades’ penitential quality, the fact that it was a form of pilgrimage, the prospect of reaching Jerusalem, service to the Lord, and the “salvatory” potential of the enterprise.
Bull notes that the knights who authored such charters reveal two key themes; first, the knights understood that “pious conviction needed to be translated into actions that were visible, irreversible, and with potentially serious, even damaging, consequences for the actor.” Thus words must be accompanied by action, for which the crusade provided the perfect opportunity (the crusading vow and the crusade itself). Second, the knights were fearful of the consequences of sin and the fact that they understood sin to be inevitable in “the competitive world of aristocratic society.” Indeed, pride was a constant threat to members of such a community as was serial polygamy, which was deemed necessary to insure dynastic continuity. Consequently, the authors of the charters, Bull notes, instinctively turn to local religious communities, often their local churches and intercessors, for intercessory support before their departure to the East. Indeed, Bull argues that the pious practices and impulses of the laity, on a local level, in the years before 1095 are what pre-conditioned the crusade response. It was the local church, Bull argues, rather than anything coming from Rome, that “served as the most effective focus of devotion for people whose religious instruction was typically based on oral and visual sources of information.”
 See Marcus Bull, “The Roots of Lay Enthusiasm for the First Crusade.” History 78 (1993), 353-72 and Knightly Piety and the Lay Response to the First Crusade: The Limousin and Gascony, c. 970-c. 1130. (Oxford: Clarendon Press, 1993).
 Erdmann, Carl. The Origins of the Idea of the Crusade, trans. M. W. Baldwin and Walter Goffart, Princeton, NJ, 1977. (Translated from the original German published in 1935).
 Bull, Roots, (p. 176 in Madden, Essential Readings).
 Bull, Knightly Piety, 179-180. .
 Bull, Knightly Piety, 177-179.
 Bull, Roots, (p. 184 in Madden, Essential Readings).
 Bull, Roots, (p. 189 in Madden, Essential Readings).
 Bull, Roots, (p. 190 in Madden, Essential Readings).
 Bull, Roots, (p. 186 in Madden, Essential Readings).