In the year 637 the armies of Islam lead by the Caliph Omar conquered the city of Jerusalem, the center of the Christian world and a magnet for Christian pilgrims. The city's Muslim masters exhibited a certain level of religious tolerance. No new churches were to be built and crosses could not be publicly displayed outside church buildings, but the pilgrims were allowed to continue their treks to the holiest shrines of Christendom. The situation remained stable for over 400 years. Then, in the latter part of the 11th century, the Turks swarmed westward out of Central Asia overrunning all that lay in their path. Jerusalem fell to them in 1076.

Reports of robberies, beatings, killings, degradation of holy sites and the kidnapping for ransom of the city's patriarch made their way back to Europe. To the Europeans the Holy Land was now in the smothering grip of the Infidel and something must be done.

In response, Pope Urban II called a conference at the city of Clermont, France in 1095, concluding the eight days of deliberation with one of history's most influential speeches. Mounting a lofty scaffold, the Pope exhorted the assembled multitude to wrest the Holy Land from the hands of the Infidel and assured them that God would absolve them from any sin associated with the venture. His words fell on receptive ears as the crowd responded with cries of "It is the will of God!", "It is the will of God!". The Crusades had begun.

Since the 11th century, the city economy in Western Europehas been rapid development, domestic and foreign trade has also been an unprecedented development, the accumulationof wealth in Western Europe reached a new height, andEuropean businessmen (especially Italianbusinessman)Oriental luxury fabrics, weapons and spicesshipped to the West, to promote local economic development,promote the people's living standard has been raised at the same time also makes the feudal nobles the material comforts constantly improve. The hedonism desire is growing, but at their disposal to meet this desire of material is limited.They desperately hoping to find more wealth to meet theirmaterial desires.

All of the Crusades came from Europe, from the kingdoms of France, England, and Germany. The armies of those kingdoms were led by the pope to the Holy Land, and to Byzantine, where they had to conquer and free the city from Muslim rule. All 8 of the Crusades began in Europe, and ended in either the Holy Land or another Muslim controlled land
. Thus the prominent part which the Popes took in the enterprises naturally fostered their authority and influence, by placing in their hands, the armies and resources of Christendom, and accustoming the people to look to them as guides and leaders.

often for a mere fraction of their actual value, of the estates of those preparing for the expeditions, or by the out and out gift of the lands of such in return for prayers and pious benedictions.

the stream of the ordinary gifts of piety was swollen by the extraordinary fervor of religious enthusiasm which characterized the period into enormous proportions. In all these ways, the power of the Papacy and the wealth of the Church were vastly augmented

. The elegance of the Orient, with its silks, tapestries, precious stones, perfumes, spices, pearls, and ivory, was so enchanting that an enthusiastic crusader called it "the vestibule of Paradise."

This enrichment of the civilization of the West with the "spoils of the East" can be seen in the artefacts displayed in modern European museums.

The Crusades contributed to increase the wealth of the Church and the power of the Papacy. Thus the prominent part which the Popes took in the enterprises naturally fostered their authority and influence, by placing in their hands, the armies and resources of Christendom, and accustoming the people to look to them as guides and leaders.

As to the wealth of the churches and monasteries, this was augmented enormously by the sale to them, often for a mere fraction of their actual value, of the estates of those preparing for the expeditions, or by the out and out gift of the lands of such in return for prayers and pious benedictions.
Thousands of the crusaders, returning broken in spirits and in health, sought an asylum in cloistral retreats, and endowed the establishments that they entered with all their worldly goods

Besides all this, the stream of the ordinary gifts of piety was swollen by the extraordinary fervor of religious enthusiasm which characterized the period into enormous proportions. In all these ways, the power of the Papacy and the wealth of the Church were vastly augmented.