Christian and Muslim states had been in conflict since the establishment of Islam in the 7th century. In the span of approximately 120 years after the death of the Islamic prophet
Muhammad in 632, Muslim forces
conquered the Levant (including
Jerusalem), as well as
North Africa and most of the
Iberian Peninsula, all of which had previously been under Christian rule. Approximately two-thirds of land held by Christians had been conquered by Muslim forces prior to the First Crusade. 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
Alexandria,
Antioch,
Constantinople and
Jerusalem. In 1054, theological disputes over Papal Supremacy, Eucharistic practices, and the insertion of the
Filioque Clause into the
Nicene Creed prompted
Pope Leo IX to send a legation to Patriarch
Michael I Cerularius of Constantinople, which ended in mutual excommunication and the
East–West Schism. 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
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.
Pope Alexander II developed recruitment systems via oaths for military resourcing that
Pope 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 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. On the Iberian Peninsula, there was no significant Christian polity. The Christian realms of
León,
Navarre, and
Catalonia lacked a common identity or shared history based on tribe or ethnicity, resulting in frequent periods of unity and division 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 of Aquitaine led a combined force of French,
Aragonese and
Catalan knights in the
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. 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. 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. 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
Invexillum sancti Petrior, or banner of St. Peter.
Robert Guiscard captured the Byzantine city of
Bari in 1071 and campaigned along the Eastern
Adriatic coast around
Dyrrachium in 1081 and 1085.
Situation in the East Since its founding, the Byzantine Empire was a historic centre of wealth, culture and military power. Under
Basil II, the territorial recovery of the empire reached its furthest extent in 1025. The Empire's frontiers stretched east to Iran, Bulgaria and much of southern Italy were under control, and piracy in the Mediterranean Sea had been suppressed. Relations with the Empire's Islamic neighbours were no more quarrelsome than relations with the
Slavs or Western Christians.
Normans in Italy;
Pechenegs,
Serbs and
Cumans to the north; and Seljuk Turks in the east all competed with the Empire, and to meet these challenges the emperors recruited mercenaries, even on occasion from their enemies. The Islamic world also experienced great success since its foundation in the 7th century, with major changes to come. The first waves of
Turkic migration into the Middle East enmeshed Arab and Turkic history from the 9thcentury. The status quo in Western Asia was challenged by later waves of Turkish migration, particularly the arrival of the
Seljuk Turks in the 10thcentury. These were a minor ruling clan from Transoxania. They converted to Islam and migrated to Iran to seek their fortune. In the following two decades they conquered Iran, Iraq and the Near East. The Seljuks and their followers were Sunni Muslims, which led to conflict in
Palestine and Syria with the Shi'ite
Fatimid Caliphate. '', mid-13th century miniature (detail),
Konya, Sultanate of Rum. The Seljuks were nomads, Turkish-speaking, and occasionally shamanistic, unlike their sedentary, Arabic-speaking subjects. This was a difference that weakened power structures when combined with the Seljuks' habitual governance of territory based on political preferment and competition between independent princes rather than geography.
Romanos IV Diogenes attempted to suppress the Seljuks' sporadic raiding, but was defeated at the
Battle of Manzikert in 1071, the only time in history that a Byzantine emperor became the prisoner of a Muslim commander. The battle was a stinging setback that presaged notable Seljuk gains, and contributed to the call for the First Crusade. Key cities such as
Nicaea and
Antioch were lost in 1081 and 1086 respectively, cities that were especially famous in the West due to their historical significance and would later also be targets of reconquest by the crusader armies. From 1092, the status quo in the Middle East disintegrated following the death of the effective ruler of the Seljuk Empire,
Nizam al-Mulk. This was closely followed by the deaths of the Seljuk sultan
Malik-Shah and the Fatimid caliph
al-Mustansir Billah. Wracked by confusion and division, the Islamic world disregarded the world beyond, so that, when the First Crusade arrived, it came as a surprise. Malik-Shah was succeeded in the Anatolian
Sultanate of Rûm by
Kilij Arslan, and in Syria by his brother
Tutush I who started a civil war against
Berkyaruq to become sultan himself. When Tutush was killed in 1095, his sons
Ridwan and
Duqaq inherited
Aleppo and
Damascus, respectively, further dividing Syria amongst emirs antagonistic towards each other, as well as
Kerbogha, the
atabeg of Mosul. Egypt and much of Palestine were controlled by the Fatimids. The Fatimids, under the nominal rule of caliph
al-Musta'li but actually controlled by vizier
al-Afdal Shahanshah, lost Jerusalem to the Seljuks in 1073 but succeeded in recapturing the city in 1098 from the
Artuqids, a smaller Turkish tribe associated with the Seljuks, just before the arrival of the crusaders.
Persecution of Christians According to historian
Jonathan Riley-Smith and
sociologist of religion Rodney Stark, Muslim authorities in the Holy Land often enforced harsh rules "against any open expressions of the Christian faith": Stark maintained; Stark appears to be mis-quoting
Hugh of Flavigny, who did indicate that locals threw stones at Richard, but, Richard did not die - he retired to a hermitage near
Remiremont Abbey, but returned to Saint-Vanne around 1039. The
persecution of Christians became even worse after the Seljuk Turks invasion. Villages occupied by Turks along the route to Jerusalem began exacting tolls on Christian pilgrims. In principle, the Seljuks allowed pilgrims access to Jerusalem, but they often imposed huge tariffs and condoned local attacks. Many pilgrims were kidnapped and sold into slavery while others were tortured. Soon only large, well-armed groups would dare to attempt a pilgrimage, and even so, many died and many more turned back. The pilgrims that survived these extremely dangerous journeys, “returned to the West weary and impoverished, with a dreadful tale to tell.” News of these deadly attacks on pilgrims as well as the persecution of the native Eastern Christians caused anger in Europe. News of these persecutions reached European Christians in the West in the few years after the
Battle of Manzikert. A Frankish eyewitness says: "Far and wide they [Muslim Turks] ravaged cities and castles together with their settlements. Churches were razed down to the ground. Of the clergyman and monks whom they captured, some were slaughtered while others were with unspeakable wickedness given up, priests and all, to their dire dominion and nuns—alas for the sorrow of it!—were subjected to their lusts." It was in this climate that the Byzantine emperor
Alexios I Komnenos wrote a letter to
Robert II of Flanders saying: The emperor warned that if Constantinople fell to the Turks, not only would thousands more Christians be tortured, raped and murdered, but “the most holy relics of the Saviour,” gathered over the centuries, would be lost. “Therefore in the name of God... we implore you to bring this city all the faithful soldiers of Christ... in your coming you will find your reward in heaven, and if you do not come, God will condemn you.” In 1009 al-Hakim ordered Yaruk, governor of Ramla, "to demolish the church of the Resurrection and to remove its symbols, and to get rid of all trace and remembrance of it." This referred to the
Church of the Holy Sepulchre, the site where Christians believed Jesus was entombed. The church was "knocked to its foundations," and even much of the cave was scraped away. Constantine's church of the Martyrion was demolished and has yet to be rebuilt. Later, al-Hakim's successor permitted reconstruction of the church, although the destruction done to the grotto was permanent. News of this outrage was spread through Europe by multiple eyewitnesses, including Ulric, bishop of Orléans and Adémar of Chabannes, and contributed to the zealous response to Pope Urban II's call for the First Crusade. ==Council of Clermont==