What Started the Crusades? | 7 Things You Never Knew About the Crusades


The Crusades were a set of wars or military campaigns especially between Western Christians and Muslims in the Eastern Mediterranean world in the eleventh through thirteenth centuries AD. The Crusades have had profound effects on relationships between Christians, Muslims, and Jews to the present day. The word Crusade evolved from the word crux, which is Latin for cross, referring to the crosses that Western Christian soldiers wore on their uniforms and shields during the battles. 

Islam began expanding within the Arabian Peninsula in the seventh century as a result of the life and legacy of Muhammad, the prophet of Islam. The term Muslim refers to a follower of the religion of Islam, and the term Arab is an ethnic designation for people who come from the Arabian Peninsula and the surrounding regions. The terms are not perfectly interchangeable, though many Arabs are Muslims. When Islam and Arabs expanded into western Asia, eastern Europe, northern Africa, and Spain, it caused great concern among European Christians. Regions conquered by Muslim Arabs were called caliphates, and the caliphs created religious-political administrations that created and executed law according to their interpretations of the Quran. The caliphs generally allowed Christians and Jews in their territories to continue to practice their own religions as long as they did not attempt to build new churches or convert others to their faith, and as long as they paid taxes to the caliph.

Judaism, Christianity, and Islam—the three most prominent monotheistic religions in world history—all considered Jerusalem to be a holy city. Following the Bar Kokhba Rebellion in AD 135, Jews were expelled from Jerusalem by the Roman Empire. When a new eastern capital for the Roman Empire was built in Constantinople (also known as Byzantium), this new capital, now located closer to Jerusalem than Rome had been, oversaw the government of Jerusalem. 

In the year 636, Byzantine troops were defeated by Muslim troops at the Battle of Yarmuk, after which Muslims occupied and governed Jerusalem. To the Jews, Jerusalem was their political and religious capital. To the Christians, it was the location of much of Jesus Christ’s ministry, as well as the place of His death, resurrection, and ascension. To the Muslims it was the original location Muhammad instructed Muslims to face when praying and later the location from which he was said to have ascended on his miraculous “night journey” through the heavens. Jews, Christians, and Muslims have, and still do, earnestly argue for their claims to the holy city of Jerusalem. These arguments became the focal point of the reasons for the Crusades beginning in the eleventh century. 

Although there were multiple causes for Western involvement in the Crusades, the three causes most mentioned by historians are: 

  1. Concerns about Muslim expansion into formerly Christian lands
  2. The desire for Western pilgrims to visit Jerusalem and Palestine safely, and
  3. Hopes for reunification between Western Catholic and Eastern Orthodox Christians.

Though there were frequent tensions between Eastern and Western Christians throughout the Middle Ages, the “Great Schism” occurred in the year 1054 and is the subject of another video. Those who longed for unity between Eastern and Western Christians saw the invasion of Christian lands by Muslims to be a common cause, which might help reunify the church. Christian pilgrims had been allowed to travel freely to Jerusalem and access the holy places when the city was being governed by the Muslim Fatimids of Egypt. However, in the year 1070, the Muslim Seljuq Turks took Jerusalem from the Fatimids, and from that time, Christian pilgrims returned with stories of oppression and desecration. In 1088, Peter the Hermit’s letter to Pope Urban II gave details of the persecution.

Byzantine Emperor Alexius I had his own problems to handle in the East. The Byzantine Empire had internal strife, disruptive heresies, and was increasingly isolated from the West. The Byzantine borders were shrinking, and the Byzantine Empire was falling behind other European nations to the west. The Byzantines were also concerned about Muslim expansion from the east. Alexius I sent delegates to Pope Urban II asking for help from the West to assist Alexius I in driving the Turks further to the east.

Some of the concerns behind the Crusades were economic in nature too. Italian merchants from Pisa, Genoa, and Venice, for example, were eager to regain safe and productive shipping lanes across all parts of the Mediterranean Sea. Ships from these cities would transport many of the Crusaders to important coastal locations where the Crusades took place. However, transportation of troops via the sea was an expensive matter, and the Italian shipping companies were able to profit from this task.

The pope was not a military leader; plus, he had no authority over European troops. So, Pope Urban II realized that if he wanted to improve his political standing in Europe and his religious influence throughout the world, he would have to appeal to land-owning nobility to fund and mobilize their own troops for a common cause. The cause was the retaking of Jerusalem from the Seljuq Turks to make pilgrimages safe to Jerusalem and other holy sites for Christians. In November 1095, Urban II presided over the Council of Clermont, where he openly called for the West to provide troops to assist Byzantine Emperor Alexius in his campaign to push back the Turks. Urban II then traveled throughout northern Italy and southern France to convince the nobility that God had given Christians weapons, bravery, and strength to remove holy lands from an “accursed” and “wicked race” as a way to ensure their remission of sins and reward of glory in the Kingdom of Heaven. According to Everett Ferguson, “the privilege of the crusaders to receive forgiveness from punishment for sins . . . had a parallel in the promise to go to paradise given to Muslim warriors in a holy war.” Urban’s speeches were met with cries of “God wills it!”

The stage was set for the First Crusade and other crusades that would follow. Though there is disagreement among historians as to which military campaigns should be included among the list of official Crusades, there is agreement on what they were: religiously infused, Christian military efforts to halt the western spread of Islam and retake Christian control of Jerusalem and other holy places in and around Palestine.  Since Jesus’ death for the sins of the world was on a cross, the cross became a symbol of Christ’s love for the world. Sadly, it also became a symbol of religiously infused warfare and war crimes committed by Western European troops who bore the symbol of the cross on their uniforms and shields. The next video in this series will examine the first and most notable of the crusades, which took place in the years 1095 to 1099.

  1. The Oxford Dictionary of the Christian Church, s.v. “Crusades,” second edition (New York: Oxford University Press, 1993).
  2. Oxford Dictionary of English, s.v. “Arab” and “Muslim,” third edition (New York: Oxford University Press, 2010).
  3. John L. Esposito, editor. The Oxford History of Islam (New York: Oxford University Press, 1999), 60.
  4. John L. Esposito, editor. The Oxford History of Islam (New York: Oxford University Press, 1999), 307.
  5.  Jews trace their political and religious claims of Jerusalem’s priority back to King David’s capturing of it in about the year 1000 BC. Most of the Old Testament from the books from 2 Samuel and after focus on Jerusalem. 
  6.  The four Gospels of the New Testament describe Jesus’ life and ministry in Jerusalem, Judea, and Galilee.
  7.  John L. Esposito, editor. The Oxford History of Islam (New York: Oxford University Press, 1999), 312.
  8.  Will Durant, The Story of Civilization: Volume IV—The Age of Faith (New York: Simon and Schuster, 1950), 585.
  9.  Will Durant, The Story of Civilization: Volume IV—The Age of Faith (New York: Simon and Schuster, 1950), 586.
  10.  Everett Ferguson, Church History: Volume One—From Christ to the Pre-Reformation, second edition (Grand Rapids: Zondervan, 2013), 418-419.
  11.  Pope Urban’s Speech at Clermont in Auvergne, France in November 1095, as cited in F. Ogg Source Book of Medieval History (1907) by Will Durant, The Story of Civilization: Volume IV—The Age of Faith (New York: Simon and Schuster, 1950), 587.
  12.  Everett Ferguson, Church History: Volume One—From Christ to the Pre-Reformation, second edition (Grand Rapids: Zondervan, 2013), 416.