The Crusades may be regarded partly as the decumanus fluctus in the surge of religious revival, which had begun in western Europe during the 10th, and had mounted high during the 11th century; partly as a chapter, and a most important chapter, in the history of the interaction of East and West. Contemporaries regarded them in the former of these two aspects, as "holy wars" and "pilgrims' progresses" towards Christ's Sepulchre; the reflective eye of history must perhaps regard them more exclusively from the latter point of view. Considered as holy wars the Crusades must be interpreted by the ideas of an age which was dominated by the spirit of otherworldliness, and accordingly ruled by the clerical power which represented the other world. They are a novum salutis genus - a new path to Heaven, to tread which counted "for full and complete satisfaction" pro omni poenitentia and gave "forgiveness of sins" (peccaminum remissio) {*1*}; they are, again, the "foreign policy" of the papacy, directing its faithful subjects to the great war of Christianity against the infidel.
As such a novum salutis genus, the Crusades connect themselves with the history of the penitentiary system; as the foreign policy of the Church they belong to that clerical purification and direction of feudal society and its instincts, which appears in the institution of "God's Truce" and in chivalry itself. The penitentiary system, according to which the priest enforced a code of moral law in the confessional by the sanction of penance - penance which must be performed as a condition of admission to the sacrament of the Eucharist - had been from early times a great instrument in the civilization of the raw Germanic races. Penance might consist in fasting; it might consist in flagellation; it might consist in pilgrimage. The penitentiary pilgrimage, which seems to have been practised as early as A.D. 700, was twice blessed; not only was it an act of atonement in itself, like fasting and flagellation; it also gained for the pilgrim the merit of having stood on holy ground. Under the influence of the Cluniac revival, which began in the 10th century, pilgrimages became increasingly frequent; and the goal of pilgrimage was often Jerusalem. Pilgrims who were travelling to Jerusalem joined themselves in companies for security, and marched under arms; the pilgrims of 1064, who were headed by the archbishop of Mainz, numbered some 7,000 men.
When the First Crusade finally came, what was it but a penitentiary pilgrimage under arms - with the one additional object of conquering the goal of pilgrimage? That the Pilgrims' Progress should thus have turned into a Holy War is a fact readily explicable, when we turn to consider the attempts made by the Church, during the 11th century, to purify, or at any rate to direct, the feudal instinct for private war (Fehde). Since the close of the 10th century diocesan councils in France had been busily acting as legislatures, and enacting "forms of peace" for the maintenance of God's Peace or Truce (Pax Dei or Treuga Dei). In each diocese there had arisen a judicature (judices pacis) to decide when the form had been broken; and an executive, or communitas pacis, had been formed to enforce the decisions of the judicature. But it was an easier thing to consecrate the fighting instinct than to curb it; and the institution of chivalry represents such a clerical consecration, for ideal ends and noble purposes, of the martial impulses which the Church had hitherto endeavoured to check. In the same way the Crusades themselves may be regarded as a stage in the clerical reformation of the fighting laymen. As chivalry directed the layman to defend what was right, so the preaching of the Crusades directed him to attack what was wrong - the possession by "infidels" of the Sepulchre of Christ.
The Crusades are the offensive side of chivalry: chivalry is their parent - as it is also their child. The knight who joined the Crusades might thus still indulge the bellicose side of his genius - under the aegis and at the bidding of the Church; and in so doing he would also attain what the spiritual side of his nature ardently sought - a perfect salvation and remission of sins. He might butcher all day, till he waded ankle-deep in blood, and then at nightfall kneel, sobbing for very joy, at the altar of the Sepulchre - for was he not red from the winepress of the Lord? One can readily understand the popularity of the Crusades, when one reflects that they permitted men to get to the other world by fighting hard on earth, and allowed them to gain the fruits of asceticism by the ways of hedonism. Nor was the Church merely able, through the Crusades, to direct the martial instincts ofa feudal society; it was also able to pursue the object of its own immediate policy, and to attempt the universal diffusion of Christianity, even at the edge of the sword, over the whole of the known world.
Thus was renewed, on a greater scale, that ancient feud of East and West, which has never died. For a thousand years, from the Hegira in 622 to the siege of Vienna in 1683, the peril of a Mahommedan conquest of Europe was almost continually present. From this point of view, the Crusades appear as a reaction of the West against the pressure of the East - a reaction which carried the West into the East, and founded a Latin and Christian kingdom on the shores of Asia. They protected Europe from the new revival of Mahommedanism under the Turks; they gave it a time of rest in which the Western civilization of the middle ages developed. But the relation of East and West during the Crusades was not merely hostile or negative. The Latin kingdom of Jerusalem was the meeting-place of two civilizations: on its soil the East learned from the West, and - perhaps still more - the West learned from the East. The culture developed in the West during the 13th century was not only permitted to develop by the protection of the Crusades, it grew upon materials which the Crusades enabled it to import from the East. Yet the debt of Europe to the Crusades in this last respect has perhaps been unduly emphasized. Sicily was still more the meeting-place of East and West than the kingdom of Jerusalem; and the Arabs of Spain gave more to the culture of Europe than the Arabs of Syria.
{*1* Fulcher of Chartres, 1, i. For what follows, with regard to the Church's conversion of guerra into the Holy War, cf. especially the passage - "Procedant contra infideles ad pugnam jam incipi dignam qui abusive privatum certamen contra fideles consuescebant distendere quondam." }
Extracted from the entry for CRUSADES in the 1911 Encyclopedia Britannica, the text of which lies within the public domain.