Sébastien Mamerot in the context of "Crusading movement"

The Crusading movement was a major religious, political and military endeavour of the Middle Ages—began in 1095 when Pope Urban II, at the Council of Clermont, proclaimed the First Crusade to liberate Eastern Christians from Muslim rule. He framed it as a form of penitential pilgrimage, offering spiritual rewards. By then, papal authority in Western Christendom had grown through church reforms, and tensions with secular rulers encouraged the notion of holy war—combining classical just war theory, biblical precedents, and Augustine's teachings on legitimate violence. Armed pilgrimage aligned with the era's Christocentric and militant Catholicism, sparking widespread enthusiasm. Western expansion was further enabled by economic growth, the decline of older Mediterranean powers, and Muslim disunity. These factors allowed crusaders to seize territory and found four Crusader states. Their defence inspired successive Crusades, and the papacy extended spiritual privileges to campaigns against other targets—Muslims in Iberia, pagans in the Baltic, and other opponents of papal authority.

The Crusades fostered distinctive institutions and ideologies, having a great impact on medieval Europe and the Mediterranean. Though aimed primarily at the warrior elite through appeals to chivalric ideals, they depended on broad support from clergy, townspeople, and peasants. Women, despite being discouraged, were involved as participants, proxies for absent crusaders, or victims. Although many crusaders were motivated by indulgences (remission of sins), material gain also played a part. Crusades were typically initiated through papal bulls, with participants pledging to join by "taking the cross"—sewing a cross onto their garments. Failure to fulfil vows could result in excommunication. Periodic waves of zeal produced unsanctioned "popular crusades".