Causes of the First Crusade


Cluniac Reforms

Church Within a Church 

  • Became a church within a church in the 11th century.
  • They made radical changes to the catholic church.
  • The Catholic Church's power over the secular world increased massively.
  • This increased piety and made more people go on crusade.

"Without this change in mood the crusades would not have developed as and when they did." - Bartlett.

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Christian Holy War

Just War

  • The church had to be able to justify going to war if there was to be a crusade.
  • The Just War theory enabled the church to go to waar if they were regaining lost territory.
  • This meant the church could go to war without going against God.

"God wills it!" - People of the 11th Century.

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Social/Economic Factors

Improvements in Agriculture

  • Agriculture of this time had made a massive improvement.
  • Much more food was being grown.
  • This meant the crusaders could stay well supllied as the agriculture backed a full crusade.


  • All assets and land of the father went to his eldest son.
  • The youngest sons got nothing.
  • They either chose the church or the army.
  • Most children chose the army over the church.
  • This meant there were a lot of knights available to go on crusade.

Mediterranean Trade

  • Mediterranean Trade was flourishing.
  • Most leaders wanted to stop Byzantine from falling into Muslim hands as it would affect trade.
  • They therefore backed and got involved in a crusade.
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Knights Dilemma


  • The knights wanted to fight, but killing went against the ten commandments.
  • The church changed the commandment from "thou shalt not kill" to "thou shalt not murder".
  • This meant they could now fight and they knew the church was behind them.

"If knights were forbidden to pursue their profession within Christendom, then just causes had to be found without" - Tyreman.

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Tradition of Pilgrimage


  • Piety was high in 11th century Christendom.
  • One way to  waavoid going to hells pilgrimage.
  • Pilgrimage was very popular at this time.
  • Jerusalem was the most important sight for Christians.
  • The crusades were a perfect way to go on pilgrimage to Jerusalem.

"The crusades were a logical extension of pilgrimage" - Mayer.

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Importance of Jerusalem


  • Jerusalem was of main importance to Islam, Christianity and Judaism.
  • Whichever religion had control of Jerusalem was seen to have God on their side.
  • The Muslims had it, so the Christians had to take it back.

"The mere sound of of the name Jerusalem had a glittering and magical splendour for the men of the 11th century."

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Peace and Truce of God

Truce Days

  • The church attempted to control warfare.
  • They created "truce days" where no one could fight.
  • As this failed and the church were defeated, they had to join the knights.

"Unable to win war, the church would seek to control it."

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