Called crusade any of the military movements of Christian inspiration departed from Western Europe toward the Holy Land and the city of Jerusalem in order to conquer them, occupy them and keep them under Christian rule. These movements were spread between the eleventh and thirteenth centuries, a time when Palestine was under control of the Muslim Turks. In the Middle East, the Crusades were called "Frankish invasions", as the local people saw these movements as armed invasions and why most crusaders came from the former territories of the Carolingian Empire and called themselves Franks.
The word crusade was not known in historical time in which it occurred. At the time they were used, among others, the terms "pilgrimage" and "holy war". The term Crusade arose because participants saw themselves as soldiers of Christ, distinguished by the cross affixed to their clothes. The Crusades were also a pilgrimage, a form of payment to any promise, or a way of asking some grace, and was considered a penance.
The crusades arose because the Turks on Palestine was perceived by Western Christians as a threat and a form of repression of pilgrims and Christians of the East. On January 27, 1095 , at the Council of Clermont, Pope Urban II called upon the French nobles to free the Holy Land and Jerusalem put back under Christian sovereignty, presenting this military expedition as a form of penance. This crowd enthusiastically accepted the challenge and soon departed eastward, overlapping a red cross on their clothes, hence they received the name "Crusaders".
Traditionally speaking in nine Crusades, but in reality, they were an almost constant motion.
The Crusades influenced the European cavalry, and for centuries, its literature. On one hand deepened the hostility between Christianity and Islam, on the other encouraged the economic and cultural contacts for permanent benefit of European civilization. Trade between Europe and Asia Minor and Europe has increased considerably new products, especially sugar and cotton. Cultural contacts established between Europe and the East had a stimulating effect on Western knowledge and, to some extent, prepared the way for the Renaissance.