In part this was a consequence of Islamic law. For those Christians and Jews, People of the Book, living within Muslim lands, the so-called Dar al-Islam (House of Islam), religious tolerance was guaranteed by the early Islamic texts. Sura 109 of the Koran declared:
Unbelievers, I do not serve what you worship, nor do you serve what I worship. I shall never serve what you worship nor will you ever serve what I worship. You have your own religion, and I have mine.
In return for Islamic rule and protection, the People of the Book had to recognize their subordinate status and pay a tax, the jizya. Despite the reaction of some modern sentimentalists, there was little of generosity but much of pragmatism in these rules. By contrast, beyond the world of Islamic order, in the Dar al-harb (House of War), non-Islamic political structures and individuals were open to attack. All the world must recognize or embrace Islam through conversion or subjugation. Thus on the Muslim community was enjoined jihad, struggle. In classical Islamic theory, i.e. traditionally from the seventh and eighth centuries but possibly later, this took two forms, the greater (al-jihad al-akbar), the internal spiritual struggle to achieve personal purity, and the lesser (al-jihad al-asghar), the military struggle against infidels. Both were obligatory on able-bodied Muslims. Unlike Christian concepts of holy war, to which the Islamic jihad appears to have owed nothing, jihad was fundamental to the Faith, described by some as a sixth pillar of Islam. In theory, fighting was incumbent on all Muslims until the whole world had been subdued, but it was a spiritual as well as military exercise from the start, and a corporate not individual obligation.
In practice, after the first century of conquest, accommodation was regularly achieved across religious and political frontiers. Islam was not in a constant state of aggression against neighbours and was no more actively militant than their enemies. Continued, almost ritualized raiding across stable frontiers in Asia Minor or Spain was lent added intensity during the collapse of Frankish power and continued Byzantine impotence in the west in the ninth century, highlighted by the conquest of Sicily by 830 and pirate bases being established in Calabria and Provence. However, much Muslim warfare was internal. By the mid-tenth century separate caliphates had been established, that of the Umayyads at Cordoba in Spain was of long standing and reached a pinnacle of success in this century, ending it with raids deep into Christian territory under the command of the effective ruler of Cordoba, al-Mansur. The Fatimid caliphate of north Africa had annexed Egypt in 969, buoyed by its Shi’ite heresy, a religious as well as political challenge to the Abbasids of Baghdad. The tenth century also saw a revival of Byzantine military power. Nicephoras Phocas (963–9) regained Cyprus and Syrian Antioch; his successor, John Tzimisces (969–76), campaigned in northern Iraq (974) and, in 975, in Syria and northern Palestine, his propaganda possibly even offering the prospect of a recapture of the holy sites of Jerusalem.
Yet such wars were hardly religious, even if some thought them just or holy. The Greeks wished to secure the eastern marches of Asia Minor; Nicephoras was perfectly willing to allow Muslim Aleppo to become a client, self-governing city. Al-Mansur posed as a holy warrior, yet he hired Christian mercenaries and his attack on the famous shrine of St James at Compostela in Galicia in 997 was only made possible by Christian nobles who acted as guides.36 This essentially secular pattern continued into the eleventh century, especially in Spain, where Christian adventurers rifled through the debris left by the collapse of the Cordoba caliphate from the 1030s, often in alliance with, or in the service of, Muslim princelings.
From the perspective of the western church, conflict with Islam was ipso facto meritorious in a religious context. Whatever the reality of ambitious Italian trading cities, Norman bandits, Spanish lords or even Greek princes, churchmen, in particular successive popes, conceptualized the conflict, fitting it into a wider picture of cosmic significance and individual grace. Whereas in the ninth century, Christendom appeared genuinely threatened, the frontier skirmishing of the eleventh century was of a very different order, yet the rhetoric was conversely gaudier. This was of considerable importance as the attitude to wars against the infidel in the earlier eleventh century coloured the whole approach of Urban II. The motives for holy war were always ever only partly practical, those directed against Muslims often being only tangentially related to any military necessity in defence of Christendom. What counted for successive popes was the place of these wars in Christian history and the opportunity they afforded for a revival of religious enthusiasm, devotion and piety, essentially concerns internal to the church and Christian society.
This is not to say that religion played no part in these wars. Pisan raids on Palermo in Sicily (1063) and al-Mahdiya in north Africa (1087) were consciously placed in the context of Christian service. The Norman invaders of Sicily after 1060, supported by papal encouragement and banner, were regarded by some as champions of the Faith. Their troops took Communion before battle; their efforts were sustained by visions of saints; and one Italian chronicler (who died in 1085, so avoiding the hindsight of the First Crusade that infected others) had the Norman leader Robert Guiscard declare his wish to free Christians from Muslim rule and to ‘avenge the injury done to God’.37
Pilgrimage and war marched closely together. The Pisan al-Mahdiya campaign in 1087 included a pilgrimage to Rome. Frenchmen were habitués of the pilgrimage to Compostela as well as the reconquista. A grant of indulgences by Pope Alexander II has been variously interpreted, if genuine, as applying either to war or pilgrimage or both.38 Gregory VII’s enigmatic reference to the Holy Sepulchre in 1074 hinted at a fusion of ideas, unsurprising in a pope so concerned with the ramifications of confession and penance as well as war. Partly no doubt as a consequence of an increase in pilgrimages, especially to Jerusalem, attested by Muslim as well as western observers and itself a result of the increase in Byzantine power in the Balkans and the eastern Mediterranean under Emperor Basil the Bulgar Slayer (d. 1025), there was a distinct frisson of outrage at the arbitrary destruction of the church of the Holy Sepulchre by the unstable Fatimid caliph of Egypt, al-Hakim, in 1009. Whether or not Pope Sergius IV (1009–12) encouraged the creation of a Christian relief fleet with a promise of indulgences, news of the outrage rang across the west. In a grim foreshadowing of the anti-Semitism of later Jerusalem holy warriors, a Burgundian chronicler, Ralph Glaber (d. 1046), recorded how Jewish communities in France were perversely blamed for inciting al-Hakim and were violently persecuted in consequence.39 Elsewhere, chroniclers saw those fighting wars of profit in Spain or in the Venetian defence of Bari against Muslims in 1003 as inspired by faith, as indeed may have been the participants themselves. In 1015–16, Pope Benedict VIII (1012–24) openly approved a Pisan and Genoese raid on Muslim pirate bases in Sardinia. The Limousin monk Adhemar of Chabannes (d. 1034) not only recorded the Jewish libel over the destruction of the Holy Sepulchre, adding gory details of atrocities against eastern Christians, but frequently mentioned campaigns against the Moors in Spain and, in describing a supposed Muslim attack on Narbonne c.1018, told of the Christian defenders receiving Communion before battle. Adam, who referred to his warlike lay uncles with pride, revealed a world in which religiosity and violence were as close as his lay and clerical relatives.40