God's War: A New History of the Crusades

However, in some circumstances, the mounted warrior was ineffective. Besieging cities or castles with stone walls neutralized him completely. Yet sieges played a central part in the successful prosecution of war, to annexe territory or force an opponent to come to terms. Here numbers, not equestrian panache, counted for all. Medieval warfare depended on muscle power, of men and women, horses, beasts of burden and drawers of carts. Muscle power was the medieval equivalent of modern electricity and petrol. Equally, if the besiegers either had to starve or storm a castle or a walled city into submission, the number of attackers was crucial. In addition to men, sieges required timber to build giant throwing machines and engines in and beneath which attackers could scale or undermine the city’s walls. The technology of siege warfare appears to have been more highly developed in the eastern Mediterranean, especially perhaps in Byzantium where forests and cities were both in abundance. Although fleeting references exist to large wooden siege machines in western Europe before the First Crusade, only during that expedition were westerners extensively exposed to such engines, the use of which they very quickly mastered, probably with Greek help. Timber and carpentry also provided the vital accompaniment to shipping. Western European advances in shipbuilding and navigation supplied the sinews of Europe, where communications ran along coasts and up rivers. The different physical world of the Near East, where political power and much of the internal trade were landlocked and timber was in shortening supply, gave the western attackers after 1095 their one clear military advantage.

Yet even where their military training was of least use, the elite mounted warrior played a vital role. As social leaders, they provided the money, the command structures, occasionally military knowledge. Medieval armies were collected by coercion, loyalty, the incentive of cash and idealism. The knightly classes habitually provided the first three; with the crusades they supplied the fourth as well.

The First Crusade

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The Origins of Christian Holy War

On 12 April 1096, a young castellan, Achard of Montmerle, pledged property to the great Burgundian monastery of Cluny in return for 2,000 Lyons shillings and four mules so that he could accomplish his intention to join ‘the journey to Jerusalem to fight for God against pagans and Saracens’. In a similar deal with the abbey of St Victor at Marseilles four months later the brothers Geoffrey and Guy were reported as wishing to seek Jerusalem ‘both for the grace of pilgrimage and under the protection of God, to exterminate the wickedness and unrestrained rage of the pagans by which innumerable Christians have already been oppressed, made captive and killed’.¹ The experience of that campaign, which cost Achard his life near Jaffa in June 1099, convinced his companions that they were the army of God ‘fighting for Christ’, their casualties martyrs, their cause supported in battle by the saints of heaven themselves, George, Demetrius and Blaise, ‘knights of Christ’, their success assured because ‘God fights for us’. They were no more than pursuing the task given them by Urban II on his preaching tour of 1095–6, who, in his own words to the Flemish in December 1095, hearing that the Turks had ‘in their frenzy invaded and ravaged the churches of God in the east’ and ‘seized the Holy City’, had at Clermont ‘imposed on them the obligation to undertake such a military enterprise for the remission of all their sins’.²

Fifty years later, in an account of the Second Crusade, an Anglo-Norman priest called Raoul aired a general theory of justified homicide: ‘He is not cruel who slays the cruel. He who puts wicked men to death is a servant of the Lord because they are wicked and there is ground for killing them.’³ By this time, such redefinition of Christian militancy raised few eyebrows. Some years before, the austere and massively influential Bernard, abbot of Clairvaux, a sort of one-man European moral ombudsman and one of the instigators of the Second Crusade (1146–8), voiced his approval of the union of the Militia of God and the Militia of the World in the creation of the Military Order of the Knights Templar:

The knight who puts the breastplate of faith on his soul in the same way as he puts a breastplate of iron on his body is truly intrepid and safe from everything… so forward in safety, knights, and with undaunted souls drive off the enemies of the Cross of Christ.⁴

Bernard, in his recruiting preaching and letters for the Second Crusade in 1146–7, showed intimate knowledge of the New Testament, not least the Epistles of St Paul. The Apostle was fond of martial metaphors, but his message was wholly contrary to the abbot of Clairvaux’s: