<P> Beginning in the 8th century, the Christians entered a campaign to recapture the Iberian peninsula from the Muslims, known as the Reconquista . The campaign reached a turning point in 1085 when Alfonso VI of León and Castile captured Toledo . In the same period, the Muslim Emirate of Sicily was conquered by Norman adventurer Roger de Hauteville in 1091 . Europe in this period was immersed in power struggles on many different fronts . In 1054 centuries of attempts by the Latin Church to assert supremacy over the Patriarchs of the Eastern Empire led to a permanent division in the Christian church called the East--West Schism . Following the Gregorian Reform, an assertive, reformist papacy attempted to increase its power and influence over the laity . Beginning around 1075 and continuing during the First Crusade, the Investiture Controversy was a power struggle between Church and state in medieval Europe over whether the Catholic Church or the Holy Roman Empire held the right to appoint church officials and other clerics . Antipope Clement III was an alternative pope for most of this period, and Pope Urban spent much of his early pontificate in exile from Rome . The result was intense piety and an increased interest in religious affairs amongst the general population in Catholic Europe and religious propaganda by the Papacy advocating a just war to reclaim Palestine from the Muslims . Participation in a crusade was seen as a form of penance that could counterbalance sin . </P> <P> The status quo was disrupted by the western migration of the Turkish tribes . The 1071 victory over the Byzantine army at the Battle of Manzikert, once considered a pivotal event by historians, is now regarded as one step in the expansion of the Great Seljuk Empire into Anatolia . One year later, the Turks wrested control of Palestine from the Fatimids . </P> <P> In 1095, at the Council of Piacenza, Byzantine Emperor Alexios I Komnenos requested military aid from Pope Urban II, probably in the form of a small body of mercenary reinforcements he could direct and control . Alexios had restored the Empire's finances and authority, but he still faced a number of foreign enemies, particularly the migrating Turks who had colonised the sparsely populated areas of Anatolia . At the Council of Clermont later that year, Urban raised the issue again and preached for a Crusade . Many historians consider that Urban also hoped that aiding the Eastern Church would lead to its reunion with the Western under his leadership . </P> <P> Almost immediately thereafter Peter the Hermit began preaching to thousands of mostly poor Christians, whom he led out of Europe in what became known as the People's Crusade . Peter had with him a letter he claimed had fallen from heaven instructing Christians to seize Jerusalem in anticipation of the apocalypse . Among the motivations of the Crusade was a "messianism of the poor" inspired by an expected mass ascension into heaven at Jerusalem . In Germany the Crusaders massacred Jewish communities, an event known as the Rhineland massacres and the first major outbreak of European antisemitism . In Speyer, Worms, Mainz, and Cologne the range of anti-Jewish activity was broad, extending from limited, spontaneous violence to full - scale military attacks . Despite Alexios' advice to await the nobles, the People's Crusade advanced to Nicaea and fell to a Turkish ambush at the Battle of Civetot, from which only about 3,000 Crusaders escaped . </P>

Who were the 2 religions fighting in the first crusade
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