Editing First Crusade (section)

===Situation in Europe===
By the 11th century, the population of Europe had increased greatly as technological and agricultural innovations allowed trade to flourish. The Catholic Church had become a dominant influence on Western civilization. Society was organized by [[manorialism]] and [[feudalism]], political structures whereby knights and other nobles owed military service to their overlords in return for the right to rent from lands and manors.<ref>[[Sidney Painter|Painter, Sidney]] (1969). "[http://images.library.wisc.edu/History/EFacs/HistCrus/0001/0001/reference/history.crusone.i0016.pdf Western Europe on the Eve of the Crusades] {{Webarchive|url=https://web.archive.org/web/20230104204618/http://images.library.wisc.edu/History/EFacs/HistCrus/0001/0001/reference/history.crusone.i0016.pdf |date=4 January 2023}}". In Setton, K., ''A History of the Crusades: Volume I''. pp. 3–30.</ref>

In the period from 1050 until 1080, the [[Gregorian Reform]] movement developed increasingly more assertive policies, eager to increase its power and influence. This prompted conflict with eastern Christians rooted in the doctrine of [[papal supremacy]]. The Eastern church viewed the pope as only one of the [[five patriarchs]] of the Church, alongside the patriarchates of [[Patriarch of Alexandria|Alexandria]], [[Patriarch of Antioch|Antioch]], [[Ecumenical Patriarch of Constantinople|Constantinople]] and [[Greek Orthodox Church of Jerusalem|Jerusalem]]. In 1054 differences in custom, creed and practice spurred [[Pope Leo IX]] to send a legation to Patriarch [[Michael I Cerularius]] of Constantinople, which ended in mutual excommunication and an [[East–West Schism]].<ref>Adrian Fortescue (1912). "[[wikisource:Catholic Encyclopedia (1913)/The Eastern Schism|The Eastern Schism]]". In ''Catholic Encyclopedia''. '''13.''' New York: Robert Appleton Company.</ref>

Early Christians were used to the employment of violence for communal purposes. A Christian theology of war inevitably evolved from the point when Roman citizenship and Christianity became linked. Citizens were required to fight against the empire's enemies. Dating from the works of the 4th-century theologian [[Augustine of Hippo]], a doctrine of [[Religious war#Christianity|holy war]] developed. Augustine wrote that aggressive war was sinful, but war could be justified if proclaimed by a legitimate authority such as a king or bishop, it was defensive or for the recovery of lands, and it did not involve excessive violence. The breakdown of the [[Carolingian Empire]] in Western Europe created a warrior caste who now had little to do but fight amongst themselves. Violent acts were commonly used for dispute resolution, and the papacy attempted to mitigate it.{{sfn|Asbridge|2012|pp=14–15|loc=Warfare and Violence in Latin Europe}}

[[Pope Alexander II]] developed recruitment systems via oaths for military resourcing that [[Pope Gregory VII|Gregory VII]] further extended across Europe. These were deployed by the Church in the Christian conflicts with Muslims in the [[Iberian Peninsula]] and for the [[Norman conquest of Sicily]]. Gregory&nbsp;VII went further in 1074, planning a display of military power to reinforce the principle of papal sovereignty in a holy war supporting Byzantium against the Seljuks, but was unable to build support for this. Theologian [[Anselm of Lucca]] took the decisive step towards an authentic crusader ideology, stating that fighting for legitimate purposes could result in the remission of sins.{{sfn|Runciman|1951|pp=83–92|loc=Holy Peace and Holy War}}

[[File:Map of the Iberian Peninsula (1060).svg|thumb|upright=1.6|alt=map of Iberia 1060|Christian and Muslim holdings in Iberia in 1060]]<!-- note - the map is deliberately enlarged as per MOS:IMGSIZE -->
On the Iberian Peninsula, there was no significant Christian polity. The Christian realms of [[Kingdom of León|León]], [[Kingdom of Navarre|Navarre]] and [[Principality of Catalonia|Catalonia]] lacked a common identity and shared history based on tribe or ethnicity so they frequently united and divided during the 11th and 12th centuries. Although small, all developed an aristocratic military technique and, in 1031, the disintegration of the [[Caliphate of Córdoba]] in southern Spain created the opportunity for the territorial gains that later became known as the ''[[Reconquista]]''. In 1063, [[William VIII, Duke of Aquitaine|William VIII of Aquitaine]] led a combined force of French, [[Aragon]]ese and [[wikt:Catalans|Catalan]] knights in the [[Crusade of Barbastro|Siege of Barbastro]], taking the city that had been in Muslim hands since the year 711. This had the full support of Alexander II, and a truce was declared in Catalonia with indulgences granted to the participants. It was a holy war but differed from the First Crusade in that there was no pilgrimage, no vow, and no formal authorisation by the church.{{sfn|Lock|2006|pp=205–213|loc=Crusades in the Iberian Peninsula}} Shortly before the First Crusade, Urban II had encouraged the Iberian Christians to take [[Tarragona]], using much of the same symbolism and rhetoric that was later used to preach the crusade to the people of Europe.{{sfn|Riley-Smith|2005|pp=4–7|loc=A war of liberation}}

The [[Italo-Normans]] were successful in seizing much of Southern Italy and Sicily from the Byzantines and North African Arabs in the decades before the First Crusade.{{sfn|Asbridge|2012|pp=5–8|loc=Western Europe in the Eleventh Century}} This brought them into conflict with the papacy leading to a campaign against them by [[Pope Leo IX]] who they defeated at the [[Battle of Civitate]]. Nevertheless, when they invaded Muslim Sicily in 1059, they did so under the papal banner ''[[Gonfalone of the Church|Invexillum sancti Petrior]]'', or banner of St. Peter.{{sfn|Lock|2006|pp=306–308|loc=The Proto-Crusades, or the Prehistory of Crusading}} [[Robert Guiscard]] captured the Byzantine city of [[Bari]] in 1071 and campaigned along the Eastern [[Adriatic]] coast around [[Dyrrachium]] in 1081 and 1085.{{sfn|Tyerman|2019|p=46|loc=The Mediterranean Crisis and the Background to the First Crusade}}