Early Christianity regarded the killing of a person as a terrible sin, and it was and continued to be subject to heavy penance. Moreover, in the Roman Empire Christianity was an illicit and occasionally persecuted religion; it is hardly surprising that its attitude toward the state was ambivalent and that it had within it a strongly pacifist current of feeling. But St. Paul had urged its adherents to respect the empire and its institutions, and this meant an acceptance of official violence that preserved the social order and defended the frontiers against the barbarians. Many soldiers became Christians and saw no incongruity in continuing in their profession.
When Emperor Constantine the Great (306-337) and his successors made Christianity the official religion of the empire, it was obvious that the pacifistic trend of thought could not be allowed to predominate. Christian leaders were in practice eager to use the coercive power of the state against their religious and political enemies. Accommodating the ideology of Christianity to its new position took longer and was essentially the work of St. Augustine of Hippo (354-430). He saw the wars of the Israelites in the Old Testament as holy wars, directly proclaimed by God, and therefore argued that war and violent punishment were not in themselves wrong. Since God no longer spoke directly in the new dispensation, Augustine drew on Cicero’s notion that “just wars avenge injuries”(De Officiis 1, Chap.2.35)— that war could be a sanction against evil. Such violence, like judicial power, could only be exercised by proper authority (the emperor) and had to be carried out with concern for the correction of the enemy and for a good cause, though this was not necessarily confined to self-defense.
Augustine never elaborated his ideas in a single work, and they were transmitted to posterity through the work of St. Isidore of Seville (c. 560-636), who stated that a war is just if fought for a just cause, in a spirit of charity for the enemy, and on proper authority. This rather broad notion of just war was not to be clarified or elaborated for many centuries.
The general range of these ideas accorded with certain attitudes in the early medieval West. The warrior ethic of the Germanic peoples found congenial the idea that the outcome of battle (and indeed of the judicial duel) was the judgment of God. The clergy regarded themselves as above war and forbidden from taking part in it by canon law, but they applauded secular rulers who defended the church and its property in an age of instability, and thus their approval came to be seen as validating warfare. Gregory, bishop of Tours (573-594), explained the victory of the Frankish warlord Clovis over the Arian Goths at Vouille in 507 by saying that “God was on his side.” Pope Gregory I the Great (590-604), while directing the imperial armies against the Lombard invaders of Italy, proclaimed the righteousness of their cause. A papal request for military aid against the Lombards justified Charlemagne’s conquest of Italy, while his conquest of the heathen Saxons was universally applauded as extending the Christian church.
Canon law continued to regard killing as evil, necessitating a terrible penance, but in practice the taking of life was always seen in its context. Judicial execution was endorsed by the church: had not Augustine spoken approvingly of the “barbed hooks of the executioner” (Contra lulianum 4.12.6)? Handbooks such as the eighth-century Penitential ascribed to Bede increasingly suggested lighter penance for killing in public warfare than for other kinds of murder. The great waves of attack from the pagan peoples of northern and eastern Europe and from the Muslims of Spain and the Mediterranean further strengthened a popular but undefined notion of holy war, that to fight enemies of God was just and even meritorious. The reconquest of Spain from Islam was especially seen in this light. Rome was desperately exposed to Islamic attack, so it is hardly surprising that Popes Leo IV (847-855) and John VIII (872-882) both suggested that war against such enemies of Christendom was not merely permitted but meritorious. There is no doubt that by the eleventh century popular attitudes endorsed all war against non-Christians as meritorious and, more generally, accepted the use of force, even between Christians, in a righteous cause: a papal banner was even issued for the Norman conquest of England in 1066.
These notions of holy war were scrutinized because in the late eleventh century the papacy, enmeshed in the Investiture Contest against the German emperors, needed to justify its use of force against them. The decisive formulation came in the 1140s in the Decretum of Gratian, who gathered together the ideas of Roman law and all the texts bearing upon the just war, especially those of Augustine. He stressed the inward disposition of the Christian, who should be concerned to punish his enemy only for his well-being, and elaborated Isidore’s definition with emphasis on the special role of the clergy. This body of thought was further developed, especially by St. Thomas Aquinas (1225-1274), employing Aristotelian concepts, and reached its ultimate definition in Catholic terms by Francisco de Suarez (1548-1617). The just war emerged as the mainstream of Christian thinking about the use of violence.
The relationship between the just war and the crusade is contentious amongst historians. Popular notions that certain kinds of war were permitted, even meritorious, were given definition in the age of the Investiture Contest, and this process underlay the call by Pope Urban II (1088-1099) for the First Crusade (1096-1099), which drew on popular enthusiasm for holy war. Jean Flori regards the Crusade as simply a just war directed to Jerusalem. John Gilchrist emphasizes the degree to which the crusade was sui generis. Jonathan Riley-Smith stresses papal authorization and its penitential nature as the hallmarks of the crusade, definitions of which, however, were increasingly set within the framework of the just war. Ancient precedent and authority gave the just war a permanent place in Christian thinking, but its definition emerged from wider popular beliefs in holy war that gave birth to the notion of crusade. Crusading lacked real definition before the thirteenth century, and it was only an episode in Christian thinking that arose from a particular religious temper and circumstances.
-John France
Bibliography
Flori, Jean, La guerre sainte (Paris: Aubier, 2001).
France, John, “Holy War and Holy Men: Erdmann and the Lives of Saints,” in The Experience of Crusading, ed.
Marcus Bull, Peter W. Edbury, Norman Housley, and Jonathan Phillips, 2 vols. (Cambridge: Cambridge University Press, 2003), 1: 193-208.
Gilchrist, John, “The Erdmann Thesis and the Canon Law,” in Crusade and Settlement, ed. P. W. Edbury (Cardiff: University College Cardiff Press, 1985), pp. 17-36.
Riley-Smith, Jonathan, What Were the Crusades?
(Basingstoke: Macmillan, 1977).
Russell, Frederick H., The Just War in the Middle Ages (Cambridge: Cambridge University Press, 1975). Tooke, J., The Just War in Aquinas and Grotius (London: SPCK, 1965).
Tyerman, Christopher, The Invention of the Crusades (Basingstoke: Macmillan, 1998).
World History
