What Drove Thousands to Leave Everything Behind and March on Jerusalem?

From the mid-second century, the Byzantine Empire found itself under constant attack. Nomadic tribes like the Pechenegs and Cumans raided from the north, destabilizing its borders. Then, in 1071, disaster struck at the Battle of Manzikert, where the Seljuk Turks inflicted a humiliating defeat. This battle marked a turning point, exposing the empire’s vulnerabilities and forcing it to seek help from the West.

In Europe, Pope Urban II seized the moment. He called for a crusade, urging Christians to liberate Jerusalem from Muslim control. His speech at the Council of Clermont in 1095 electrified his audience, sparking a movement unlike anything Europe had seen before. Thousands answered the call—not just knights but also peasants, driven by faith, adventure, or the hope of material gain. Leaders like Godfrey of Bouillon, a Lotharingian prince, took command of the First Crusade. Among the commoners, Peter the Hermit, a preacher who claimed firsthand knowledge of the Holy Land, led an unruly mob.

The journey to Jerusalem, however, was chaotic. Some crusading bands looted along the way, even clashing with Christian rulers like Hungary’s King Coloman, who decisively crushed them. Later waves of crusaders were better organized, avoiding such excesses and treating local communities, including Jews, with more restraint.

When the crusaders reached Constantinople, the Byzantine leadership grew uneasy. They feared this disorderly army might pose as much of a threat to their capital as to their enemies. To prevent trouble, they ferried the crusaders across the Bosporus, hurrying them toward their destination.

In 1099, after a grueling march through Anatolia and Syria, the crusaders reached Jerusalem. Their siege culminated in a brutal massacre, leaving the city soaked in blood. Yet, for the crusaders, it was a triumph. They established the Kingdom of Jerusalem and other Crusader states, including the County of Edessa and the Principality of Antioch. These fragile outposts of Christendom clung to existence, caught between the ambitions of their founders and the relentless counterattacks of Muslim forces.

The Crusades were not just military campaigns; they were a microcosm of human history—driven by faith, fear, greed, and the relentless pursuit of power. They reshaped the medieval world, creating new networks of trade, conflict, and cultural exchange that would reverberate for centuries.