The Crusades were, at the most simplistic and generalized level, a war of conversion - to take back from the 'heathens' the land where Christianity was born, that ultimately failed on all accounts. A crusade was a holy war fought against those perceived to be the external or internal foes of Christendom, for the recovery of Christian property, or in defense of the church or Christian people. As far as the Crusaders were concerned, the Muslims in the east and in Spain had occupied Christian territory, including land sanctified and made his very own by the presence of Christ himself. The First Crusade, and all Crusades thereafter, was an exceptionally violent campaign that was waged in the name of God. The Church justified the extremes of aggression and the validity of Christian violence as being an extension of the original Soldiers of God who had waged war for the supremacy of Heaven - they would be fighting for the Kingdom of God on Earth. The Crusades introduced a great deal of Eastern / Islamic culture to the West and vice versa. Ultimately, the Crusades were a failure - at least in the intended goals of dominating and creating a permanent presence in Jerusalem and the other Holy cities in the region. Toward the final crusade, the motivation had become less religious and more economic, thus causing the loss of the moral superiority assumed by the participants in the First Crusade.
