In November 1095, at a church council in Clermont in central France, Pope Urban II preached a sermon calling on the knights of Latin Christendom to march east and recover Jerusalem and the Holy Land from Muslim rule. The appeal drew on a request from the Byzantine emperor Alexios I Komnenos for military help against the Seljuk Turks, but Urban's own version of the call went further, framing the campaign as an armed pilgrimage that would earn its participants a plenary indulgence, full remission of the temporal punishment owed for confessed sin. Reports of the sermon describe the crowd interrupting with cries of Deus vult, God wills it, which became the movement's rallying cry.
What followed surprised even the pope. Alongside the organized noble armies that set out through 1096 and 1097, an unauthorized and poorly provisioned popular movement known as the People's Crusade, led by the preacher Peter the Hermit, marched ahead and was largely destroyed by Seljuk forces in Anatolia before the main armies arrived. The knightly crusade fared better, taking Nicaea in 1097, winning a hard fought siege at Antioch in 1098, and finally storming Jerusalem in July 1099, where the capture was followed by a massacre of the city's Muslim and Jewish inhabitants that later chroniclers, including some sympathetic to the crusade, recorded as extreme even by the standards of medieval siege warfare. The victors divided the conquered territory into four Crusader states, with the Kingdom of Jerusalem as the most prominent, beginning two centuries of a Latin Christian presence in the Levant that the First Crusade had neither been guaranteed nor, on its own, been able to make permanent.