Crusades

===Background===
By the end of the 11th{{nbsp}}century, the period of [[Early Muslim conquests|Islamic Arab territorial expansion]] had been over for centuries. The Holy Land's remoteness from focus of Islamic power struggles enabled relative peace and prosperity in Syria and Palestine. Muslim-Western European contact was only more than minimal in the conflict in the [[Iberian peninsula]].{{sfn|Jotischky|2004|p=40}} The Byzantine Empire and the Islamic world were long standing centres of wealth, culture and military power. They viewed Western Europe as a backwater that presented little organised threat.{{sfn|Asbridge|2012|p=8}} By 1025, the Byzantine Emperor [[Basil II]] had extended territorial recovery to its furthest extent. The frontiers stretched east to Iran. Bulgaria and much of southern Italy were under control, and piracy was suppressed in the Mediterranean Sea. The empire's relationships with its Islamic neighbours were no more quarrelsome than its relationships with the [[Slavs]] or the Western Christians. The [[Italo-Normans|Normans]] in Italy; to the north [[Pechenegs]], [[Serbs]] and [[Cumans]]; and [[Seljuk dynasty|Seljuk Turks]] in the east all competed with the Empire and the emperors recruited mercenaries{{mdash}}even on occasions from their enemies{{mdash}}to meet this challenge.{{sfn|Jotischky|2004|pp=42–46}}

The political situation in Western Asia was changed by later waves of Turkish migration, in particular the arrival of the Seljuk Turks in the 10th{{nbsp}}century. Previously a minor ruling clan from Transoxania, they had recently converted to Islam and migrated into Iran. In two decades following their arrival they conquered Iran, Iraq and the Near East. The Seljuks and their followers were from the [[Sunni]] tradition. This brought them into conflict in Palestine and Syria with the [[Fatimid Caliphate|Fatimids]] who were [[Shia Islam|Shi'ite]].{{sfn|Jotischky|2004|pp=39–41}} The Seljuks were nomadic, Turkic speaking and occasionally shamanistic, very different from their sedentary, Arabic speaking subjects. This difference and the governance of territory based on political preference, and competition between independent princes rather than geography, weakened power structures.{{sfn|Tyerman|2019|pp=43–44}} In 1071, Byzantine Emperor [[Romanos IV Diogenes]] attempted confrontation to suppress the Seljuks' sporadic raiding, leading to his defeat at the [[battle of Manzikert]]. Historians once considered this a pivotal event but now Manzikert is regarded as only one further step in the expansion of the [[Great Seljuk Empire]].{{sfn|Asbridge|2012|p=27}}

The evolution of a Christian theology of war developed from the link of [[Roman citizenship]] to Christianity, with citizens were required to fight the empire's enemies. A doctrine of [[holy war]] dated from the 4th-century theologian [[Augustine of Hippo|Saint Augustine]]. He maintained that aggressive war was sinful, but acknowledged a "[[Just war theory|just war]]" could be rationalised if it was proclaimed by a legitimate authority, was defensive or for the recovery of lands, and without an excessive degree of violence.{{sfn|Tyerman|2019|pp=14–15}}{{sfn|Asbridge|2012|pp=14–15}} Violent acts were commonly used for dispute resolution in Western Europe, and the papacy attempted to mitigate this.{{sfn|Jotischky|2004|pp=30–31}} Historians have thought that the [[Peace and Truce of God]] movements restricted conflict between Christians from the 10th{{nbsp}}century; the influence is apparent in Urban II's speeches. Other historians assert that the effectiveness was limited and it had died out by the time of the crusades.{{sfn|Jotischky|2004|pp=30–38}} [[Pope Alexander II]] developed a system of recruitment via oaths for military resourcing that his successor [[Pope Gregory VII]] extended across Europe.{{sfn|Jotischky|2004|p=31}} In the 11th{{nbsp}}century, Christian conflict with Muslims on the southern peripheries of Christendom was sponsored by the Church, including the [[Crusade of Barbastro|siege of Barbastro]] and the [[Norman conquest of Sicily]].{{sfn|Tyerman|2019|pp=18–19, 289}} In 1074, Gregory{{nbsp}}VII planned a display of military power to reinforce the principle of papal sovereignty. His vision of a holy war supporting Byzantium against the Seljuks was the first crusade prototype, but lacked support.{{sfn|Asbridge|2012|p=16}}

The First Crusade was an unexpected event for contemporary chroniclers, but historical analysis demonstrates it had its roots in earlier developments with both clerics and laity recognising [[Jerusalem in Christianity#First Crusade|Jerusalem's role in Christianity]] as worthy of penitential [[Christian pilgrimage|pilgrimage]]. In 1071, Jerusalem was captured by the Turkish warlord [[Atsiz ibn Uvaq|Atsiz]], who seized most of Syria and Palestine as part of the expansion of the [[Seljuk Turks|Seljuks]] throughout the Middle East. The Seljuk hold on the city was weak and returning pilgrims reported difficulties and the oppression of Christians. Byzantine desire for military aid converged with increasing willingness of the western nobility to accept papal military direction.{{sfn|Asbridge|2012|p=28}}{{sfn|Jotischky|2004|p=46}}