During the second half of the eleventh century, Latin Christianity began to edge ever closer towards the acceptance of holy war. In the early stages of the Reform movement, the papacy began to perceive the need for a military arm with which to reinforce its agenda and manifest its will. This prompted a succession of popes to experiment with the sponsoring of warfare, calling upon Christian supporters to defend the Church in return for vaguely expressed forms of spiritual reward. It was under the forceful guidance of Pope Gregory VII that the doctrine and application of sacred violence jumped ahead. Intent upon recruiting a papal army that owed its allegiance to Rome, he set about reinterpreting Christian tradition. For centuries theologians had characterised the internal, spiritual battle that devoted Christians waged against sin as the ‘warfare of Christ’, and monks were sometimes described as the ‘soldiers of Christ’. Gregory twisted this idea to suit his purpose, proclaiming that all lay society had one overriding obligation: to defend the Latin Church as ‘soldiers of Christ’ through actual physical warfare.

Early in his pontificate, Gregory laid plans for a grand military enterprise that can be regarded as the first real prototype for a crusade. In 1074 he tried to launch a holy war in the eastern Mediterranean in aid of the Greek Orthodox Christians of Byzantium, who were, he claimed, ‘daily being butchered like cattle’ by the Muslims of Asia Minor. Latins fighting in this campaign were promised a ‘heavenly reward’. His grandiose project fell flat, eliciting very limited recruitment, perhaps because Gregory had boldly pronounced his intention to lead the campaign in person. The pope’s 1074 formulation of the link between military service to God and the resultant spiritual recompense still lacked specificity. But in the early 1080s, with the conflict with the German emperor in full flow, Gregory took a critical step towards clarification. He wrote that his supporters should fight the emperor and face ‘the danger of the coming battle for the remission of all their sins’. This seemed to indicate that participation in this holy struggle had the same power to purify the soul as other forms of penance because it promised, just like a pilgrimage, to be both difficult and perilous. As yet, this more logical explanation for the redemptive quality of sanctified violence did not take hold, but it set an important precedent for later popes. In fact, the very novelty of Gregory’s radical approach to the militarisation of Latin Christendom caused condemnation among some contemporaries, and he was accused in ecclesiastical circles of dabbling in practices ‘new and unheard of throughout the centuries’. His vision was so extreme that, when his successor Pope Urban II offered a more measured and carefully constructed ideal, he appeared almost conservative in comparison and thus prompted less criticism.⁷

Gregory VII had taken Latin theology to the brink of holy war, arguing that the Pope had the clear right to summon armies to fight for God and the Latin Church. He also went some considerable way to grounding the concept of sanctified violence within a penitential framework–an idea that would be part of the essence of crusading. Nonetheless, Gregory cannot be regarded as the prime architect of the crusades because he manifestly failed to construct a compelling and convincing notion of holy war that resonated with the Christians of Europe. That would be the work of Pope Urban II.

THE MUSLIM WORLD

From the end of the eleventh century onwards, the crusades pitted western European Franks against the Muslims of the eastern Mediterranean. This was not because these holy wars were launched, first and foremost, to eradicate Islam, or even to convert Muslims to the Christian faith. Rather, it was a consequence of Islam’s dominion over the Holy Land and the sacred city of Jerusalem.

The early history of Islam

According to Muslim tradition, Islam was born in c. 610 CE when Muhammad–an illiterate, forty-year-old Arab native of Mecca (in modern Saudi Arabia)–began to experience a series of ‘revelations’ from Allah (God), relayed by the Archangel Gabriel. These ‘revelations’, regarded as the sacred and immutable words of God, were later set down in written form to become the Koran. During his lifetime, Muhammad set out to convert the pagan polytheist Arabs of Mecca and the surrounding Hijaz region (on the Arabian Peninsula’s western coast) to the monotheistic faith of Islam. This proved to be no easy task. In 622 the Prophet was forced to flee to the nearby city of Medina, a journey which served as the starting date for the Muslim calendar, and he then waged a bloody and prolonged war of religion against Mecca, finally conquering the city shortly before his death in 632.

The religion founded by Muhammad–Islam, meaning submission to the will of God–had common roots with Judaism and Christianity. During his life, the Prophet came into contact with adherents of these two faiths in Arabia and the eastern Roman Empire and his ‘revelations’ were presented as the perfecting refinement of these earlier religions. For this reason, Muhammad acknowledged the likes of Moses, Abraham and even Jesus as prophets, and a whole sura (or chapter) of the Koran was dedicated to the Virgin Mary.

During Muhammad’s own life, and in the few years immediately following his death, the warring tribes of the Arabian Peninsula were united under the banner of Islam. Over the next few decades, under the guidance of a series of able and ambitious caliphs (the Prophet’s successors) these Muslim Arabs proved to be an almost unstoppable force. Their incredible martial dynamism was married to a seemingly insatiable appetite for conquest–a hunger sustained by the Koran’s explicit demand for the Muslim faith and the rule of Islamic law to be spread unceasingly across the world. The Arab-Islamic approach to the subjugation of new territories also eased the path to exponential growth. Rather than requiring total submission and immediate conversion to Islam, the Muslims allowed ‘Peoples of the Book’, such as Jews and Christians, to continue in their faiths in return for the payment of a poll tax.

In the mid-630s ferocious armies of highly mobile, mounted Arab tribesmen began to pour out of the Arabian Peninsula. By 650 they had achieved startling success. With mercurial speed, Palestine, Syria, Iraq, Iran and Egypt were absorbed into the new Arab-Islamic state. Over the next century the pace of expansion slowed from this breakneck pace, but inexorable gains continued, such that in the mid-eighth century the Muslim world stretched from the Indus River and the borders of China in the east, across North Africa to Spain and southern France in the west.

In the context of crusading history, a critical stage in this whole process was the capture of Jerusalem in 638 from the Greek Christians of Byzantium. This ancient city came to be revered as Islam’s third-holiest site, after Mecca and Medina. In part this was due to Islam’s Abrahamic heritage, but it was also dependent upon the belief that Muhammad had ascended to Heaven from Jerusalem during his ‘Night Journey’, and the associated tradition identifying the Holy City as the focus for the impending End of Days.

It was once popular to suggest that the Islamic world might have swept across all Europe, had not the Muslims been twice thwarted in their attempts to capture Constantinople (in 673 and 718) and then defeated in 732 at Poitiers by Charlemagne’s Frankish grandfather Charles the Hammer. In fact, important as these reversals were, a fundamental and profoundly limiting weakness within Islam had already shown its face: intractable and embittered religious and political division. At their core, these issues related to disputes over the legitimacy of Muhammad’s caliphal successors and the interpretation of his ‘revelations’.