The Council of Clermont and the Launch of the Crusades

On November 27, 1095, Pope Urban II stood before a vast crowd gathered outside the cathedral of Clermont in central France and delivered one of the most consequential sermons in Christian history. Chroniclers say the crowd erupted with cries of “Deus vult!” — “God wills it!” — and within months, tens of thousands of men from across Western Europe had taken a vow to march to the Holy Land. The First Crusade had begun.

The Council’s Original Purpose

The Council of Clermont was not originally convened to launch a war. It was primarily a church synod focused on internal reform, part of the broader movement known as the Cluniac reforms, which sought to combat simony (the buying and selling of church offices), enforce clerical celibacy, and reassert the independence of the church from secular rulers who had grown accustomed to appointing bishops and abbots. Urban spent much of the council addressing these disciplinary matters before turning, on its final day, to the appeal that would define it.

Urban’s Call to Arms

Urban’s sermon responded to an urgent appeal from the Byzantine Emperor Alexios I Komnenos, whose empire was under pressure from Seljuk Turkish advances in Anatolia. Urban called on the knights of Western Christendom to set aside the internal warfare that had long plagued feudal Europe and instead direct their martial energy toward liberating Jerusalem and the holy places of the East from Muslim rule, promising that those who died on the campaign would receive remission of their sins.

An Unexpected Mass Movement

Urban likely anticipated a modest, professional force of knights. What followed instead was a much larger and more chaotic mass movement, including the disastrous “People’s Crusade” led by the preacher Peter the Hermit, in which thousands of poorly armed and poorly organized commoners set out for the Holy Land and were largely destroyed before reaching their destination. The main armies of knights fared better, capturing Antioch in 1098 and, after a brutal siege, Jerusalem itself in July 1099.

A Movement That Outlived Its Founder

Urban II died in 1099, just two weeks after Jerusalem fell, before news of the victory could reach him. But the movement he launched would continue for two more centuries, through a further eight major Crusades of varying success, reshaping relations between Christianity and Islam, contributing to (and later worsening) the rift between Eastern and Western Christianity, and leaving a legacy that remains deeply contested and consequential in the modern world.