Causes and Consequences of the Crusades

The holy wars known as the Crusades were a series of military campaigns authorized and organized by the church of Rome in Europe during the Middle Ages. Their official purpose was to deliver the Holy Land of Israel, particularly the city of Jerusalem from Muslim occupation and rule.


Before the Crusades

The first conquest of Palestine by Islamic forces initially had little disrupting effect on the passage of pilgrims to Holy Land sites like Jerusalem, Bethlehem, and Nazareth. However, in 1009 AD, the Fatimid caliph of Cairo, Al-Hakim, destroyed the Church of the Holy Sepulchre. His successor and son, Ali az-Zahir, allowed for the rebuilding and redecorating of the church and pilgrimages were again permitted. In 1056 AD, 300 Christians were expelled from Jerusalem and European Christians were again forbidden from entering the Church of the Holy Sepulchre.


What Caused the Crusades?

Causes in the Middle East

In the 100 years after Muhammad’s death in 632 AD. Muslim Empire had conquered the Middle East, North Africa and Spain with Portugal. In 732 Muslim advancements were stopped by Charles Martel, Frankish Ruler of the Carolingian line, who defeated the Islamic Umayyad Empire, rescuing Europe from Islamic domination.

The Byzantine army’s decisive defeat at Manzikert (Armenia) against the Seljuk Turks in the Battle of Manzikert in 1071 AD resulted in the first pledge of assistance and troops from the West. The request for more mercenaries was made by Emperor Alexius I in Byzantium in 1091 to Pope Urban II and the Count of Flanders, Robrecht I de Fries. The Crusade’s extended cause was therefore not only to recapture Jerusalem, but also to assist the Byzantine army against the Turks, to prevent territorial expansion of the Muslims, and to enlarge the influence of the West in the east.

The main cause for the Crusades was due to the fact that the Seljuk Turks, after conquering Palestine, had made Christian pilgrimages to Jerusalem and other holy sites nearly impossible. Passages to these areas had previously been possible, despite being under Islamic supervision.


Causes in Europe

In the tenth century, the invasions of Europe by Vikings, Moors, and Asians had come to an end. The resulting stability led to an expansionist movement which persisted from the 11th century onward. Forests were cleared, fens and marshes were drained, and land was reclaimed. Europe’s growing population resulted in a Drang nach Osten (“Drive to the East”) and with the Norman conquest of southern Italy, from 1029, colonization persisted for the next 100 years.

Now that the threat of foreign invaders was gone, European warriors who had previously fought the Vikings and other invading peoples began to turn against themselves and against the local population. In response to this, The Peace and Truce of God movement (Latin: Pax et treuga Dei) was initiated by the church. This was initially an appeal to local gentlemen, but later it also became a plea to Christian states to cease the internal violence. This was the appeal that Pope Urban II used to stifle the internal struggle and to focus on the common enemy of the Christian faith.

In the early Medieval period, the particulars of Christian doctrine was discussed with relative openness. Consequently, there were varying interpretations of the Pax et treuga Dei doctrine, which did not help the unity of the Church. In the 5th century, Saint Augustine of Hippo regarded heresy (from the Greek: hairesthai, meaning “choose”) – as a deviation from the true Christian faith. Dogmas were established to define that true faith. The development of dogmatism not only clarified what true faith meant, it also made clear what went against true faith.

From the eleventh century onwards, both the Church and European kingdoms were able to better define their ideologies. This resulted in a rejection of corruption and secularisation within the Church, but also in a rejection of groups that deviated from those ideologies. This affected not only Islam, but also movements such as the Bulgarelli, the Waldensians, and the Cathars. Other movements such as the Franciscans and Humiliati were recognized, but the criteria for why one group was considered as opposed to another is not clear.

In 1063, Pope Alexander II gave his blessing to the Crusaders of the Reconquista. In 1085 the Spanish took the Taifa of Toledo, and in 1092 the Muslims were expelled from Sicily. The Crusaders undoubtedly felt bolstered by this recapture of territory that had been occupied by Muslims for centuries.

Pope Innocent III determined that more extreme action should be taken against the Cathars. In 1209 he mustered an army for a crusade to Occitania. At the Fourth Council of the Lateran, a number of religious groups were condemned and others recognized. Decrees were issued against the Waldensians and the Cathars. Both Jews and Muslims were required to wear distinctive insignias.

In 1232, Pope Gregory IX directed the newly founded Dominican Order to take charge of the Inquisition. The Cathars were the first group targeted by this order, but the Jews, who enjoyed a privileged status with Augustine, were protected.


Motivations for Crusaders

Those loyal to the church believed the Crusades were a path to salvation for all those who participated. Those who joined these holy wars were to be recipients of both spiritual and earthly rewards including the following:

  • To Protect the Holy Church against dissidents.
  • To Liberate the Holy City Jerusalem from Muslim rule.
  • To undo Islamic conquests.
  • To reunite the Eastern Church with the Church of Rome.
  • To receive a general indulgence during the Crusades.


After Pope Gregory VII (1073-1085) there was an increase in church piety, which created the religious atmosphere in which the Crusades were born. The call to the Crusades also gave the Pope a certain political authority over German emperor, Henry IV. It was not customary for a spiritual leader to call for armed struggle, that was the task of secular leaders. This rivalry between the Pope and the emperor was the prelude to the Investiture controversy (or Investiture contest). This was a power struggle between church and state in medieval Europe over the ability to appoint local church officials through “investiture” – the formal installation of a person with honors or rank.

The Crusades were also a means to export internal problems within Western Europe. For the Roman Church, they afforded the perfect outlet for harmful disputes with secular authority and to turn them into a righteous cause for the faith. Numerous knights and nobles embarked on Crusades out of pure self-interest, to gain wealth and land. Many sold their entire estate to fund the conquest to the Holy Land. Traders arrived after the Crusaders in order to develop commerce with the Middle East.

The Church gave those who participated in the Crusades a full indulgence. Any penance imposed during confessions were waived. Many misunderstood this privilege as a blanket-forgiveness for all sins, even unconfessed transgressions. For the Crusader, financial gain was not guaranteed and the expenses for such an enterprise were exorbitant. Participants often subjected themselves to debilitating debt and many returned destitute. For those who participated in the Crusades, it was most likely the religious benefits that offered the greatest motivation.


How Did the Crusades Change Europe?

The social impact of the Crusades on Europe was significant. The following is a list of some of the important historical consequences of the Crusades.



The Crusades significantly enlarged the power of both the Roman Catholic Church and the Pope. Rome obtained a massive quantity of land and possessions, in part because of the personal wealth and property which was handed over to the church by hundreds of thousands of Crusaders, often before they even embarked on their mission. Consequently, the Roman Church became incredibly rich. The Crusaders also confiscated many religious artifacts from the Holy Land, which led to a boom in the trade of sacred relics in Europe. The Crusades also gave a boost to the Church’s system of indulgences.



The Crusades’ impact on the European economy cannot be understated. They ignited the shipbuilding industry in Italy, as well as the ivory, silk, spice, sugar, perfume, pearl, and carpet trades in the rest of the Mediterranean.



Approximately two- to six-million European Christians died as a result of the Crusades. Many of the victims were aristocrats and nobles. Many noblemen, dukes, graves, and knights never returned. Their property and estates fell into disrepair which undermined the feudal/loan system and stimulated the nascent formation of states and the emergence of cities.



Architectural designs from the Near East and Middle East were imported to Europe. This had a significant impact on Western European architecture. Soon, animal motifs were frequently used in building ornamentation. The Gothic style was also influenced by Eastern architectural conventions. These can be seen in the great cathedrals built during the Gothic period in France in particular.

The oriental pottery technique, which was characterized by its unique glazing method and its ornate design, was also brought over. Moreover, the Oriental contribution of the wind turbine was introduced in Europe following the Crusades, although considerably later.



The Crusaders also introduced Europe to new food products imported from the Middle East, like sugar, spinach, lettuce, and a variety of herbs.



Arabic words from botany, textiles, cuisine, and music made their way into the Crusader’s English. The mentality with regard to knightly behavior also changed after the Crusades. Their interaction with Eastern culture refined and polished their previously abrasive manner of conduct. Course songs of war gave way to poetic songs and chivalry. Concepts of romance and true love made a comeback along with literary poetry.



The Crusaders also brought new knowledge of medicine with them, as seen in the Order of the Knights Hospitaller. They also brought Arabic translations of medical manuals by authors such as Galenus and Hippocrates. Also of great significance was the translation of Aristotle’s Categories by Hunayn ibn-Ishaq (809-873), and the Canon of Medicine by Islamic scholar Avicenna (980-1035).

Particularly in Italy, many great works of antiquity came from Greek, Latin, and Islamic scientists. Emperor Frederick II (1194-1250) had numerous Arabic volumes that were translated at his court. The wealth knowledge and scientific concepts acquired from the Middle East significantly informed the Renaissance. New geographical knowledge brought by Crusades later helped men like Italian explorer Marco Polo (1254-1324) and English travel author John Mandeville (1300-1371).


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