The Crusades were a series of nine Christian military expeditions that took place during the end of the eleventh century and throughout the twelfth and thirteenth centuries. The stated goal of the Crusades was to recover from the Muslims the Holy Land of Palestine, where Jesus Christ (c. 6 B.C.–A.D. 30) lived. The word crusade comes from the Latin word crux meaning “cross,” and Crusaders were said to have “taken up the cross.”

The Crusades began with an impassioned sermon given by Pope Urban II (c. 1035–1099) at Clermont, France, in November 1095. Earlier that year Byzantine emperor Alexius I Comnenus (1048–1118) had appealed to Urban for aid in fighting back the fierce Seljuk Turks. (The Seljuk Turks preceded the Ottoman Turks; the Seljuks were named for their traditional founder, Seljuq). Seeing the expansion of the Turks, who were Muslim, as a threat to Christianity, the Pope agreed to help. Not only did Urban rally support for the Byzantines in staving off the further advances of the Turks, he also advocated that the Holy Lands should be recovered from them. While the Arab Muslims who had previously controlled the Holy Land had allowed Christians to visit there, the Turks tolerated no such thing. Urban feared that if Palestine were not recovered, Christians would lose access to their holy places altogether.

But Urban also viewed the Crusades as a way of unifying western Europe: The feudal nobility there had long fought against each other. He believed a foreign war would unite them behind a common cause as Christians. Further, he hoped the Crusades would unite western with eastern (Byzantine) Europe behind one goal. If successful, the expeditions would also expand the pope’s moral authority across a greater region.

En route from Clermont to Constantinople (present-day Istanbul, Turkey), where the Crusade was set to begin in August 1096, Urban continued to preach his message—at Limoges, Poitiers, Tours, Aquitaine, and Toulouse, France. The message found broad appeal, even if it appealed to something other than the people’s religious sensibilities. Some of those who answered Urban’s call took up arms not for the Christian cause, but for their own personal gain such as acquiring more land, expanding trade, or recovering religious relics. Many peasants “took up the cross” to escape hardships—in 1094 northern France and the Rhineland had been the site of flooding and pestilence, which was followed in 1095 by drought and famine.

The First Crusade actually turned into two. A Peasants’ Crusade (which had never been Urban’s intent) had gone ahead of the official expedition, and many lives were lost. It ended in failure. But the planned expedition, called the Crusade of Princes, ultimately succeeded in capturing Jerusalem in 1099. Western Christian feudal states were established at Edessa, Antioch, and Tripoli—all of which were placed under the authority of the Kingdom of Jerusalem. But Urban did not live to see the recovery of the Holy Land. And the Christian hold on Palestine was not to last, as the Muslims refused to give up the fight for control of lands they too considered to be holy. The Second (1147–49), Third (1189–92), Fourth (1202–04), Fifth (1217–21), Sixth (1228–29), Seventh (1248–54), and Eighth (1270) Crusades were prompted by a mix of religious, political, and social circumstances. The Crusades ended in 1291—almost 200 years after they had started—when the city of Acre, the last Christian stronghold in Palestine, fell to the Muslims, ending Christian rule in the East.

Yet another crusade, in 1212, was particularly tragic: Called the Children’s Crusade, the expedition was led by a young visionary who had rallied French and German children to believe they could recover Jerusalem—since, as poor and faithful servants, they would have God on their side. As the children marched south across Europe, many of them died even before reaching the Mediterranean coast. Some believe that the Crusade was sabotaged, resulting in the children being sold into slavery in the East.