Although conflicts in which Christians fought Christians were troubling to many thinkers, war against non-Christians was another matter. By the ninth century, popes and other church officials encouraged war in defense of Christianity, promising spiritual benefits to those who died fighting. By the eleventh century, these benefits were extended to all those who simply joined a campaign. Around this time, Christian thinkers were developing the concept of purgatory, a place where those on their way to Heaven stayed to do any penance they had not completed while alive. Engaging in holy war could shorten one’s time in purgatory, or, as many people understood the promise, allow one to head straight to paradise. Popes signified this by providing indulgences, grants with the pope’s name on them that lessened earthly penance and postmortem purgatory. Preachers communicated these ideas widely and told stories about warrior-saints who slew hundreds of enemies.

In the midst of these developments came a change in possession of Jerusalem. The Arabic Muslims who had ruled Jerusalem and the surrounding territory for centuries had allowed Christian pilgrims to travel freely, but in the late eleventh century, the Seljuk (SEHL-jook) Turks took over Palestine, defeating both Arabic and Byzantine armies (Map 9.4). The emperor at Constantinople appealed to the West for support, asserting that the Turks would make pilgrimages to holy places more dangerous and that the holy city of Jerusalem should be in Christian hands. The emperor’s appeal fit well with papal aims, and in 1095, Pope Urban II called for a great Christian holy war. Urban offered indulgences to those who would fight for and regain the holy city of Jerusalem.