Crusading movement

The crusading movement encompasses the framework of ideologies and institutions that described, regulated, and promoted the Crusades. The crusades were religious wars that the Christian Latin church initiated, supported, and sometimes directed during the Middle Ages. The members of the church defined this movement in legal and theological terms that were based on the concepts of holy war and pilgrimage. In theological terms, the movement merged ideas of Old Testament wars, that were believed to have been instigated and assisted by God, with New Testament ideas of forming personal relationships with Christ. The institution of crusading began with the encouragement of the church reformers who had undertaken what is commonly known as the Gregorian Reform in the 11th century. It declined after the 16th century Protestant Reformation.

The idea of crusading as holy war was based on the Greco-Roman Just war theory. A "just war" was one where a legitimate authority is the instigator, there is a valid cause, and it is waged with good intentions. The Crusades were seen by their adherents as a special Christian pilgrimage – a physical and spiritual journey authorised and protected by the church. The actions were both pilgrimage and penitental, Participants were considered part of Christ's army and demonstrated this by attaching crosses of cloth to their outfits. This marked them as followers and devotees of Christ and was in response to biblical passages exhorting Christian "to carry one's cross and follow Christ". Everyone could be involved, with the church considering anyone who died campaigning a Christian martyr. This movement was an important part of late-medieval western culture, that impacted politics, the economy and wider society.

The original focus and objective was the liberation of Jerusalem and the sacred sites of Palestine from non-Christians. The city was considered to be Christ's legacy and it was symbolic of divine restoration. The site of Christ's redemptive acts was pivotal for the inception of the First Crusade and the subsequent establishment of crusading as an institution. The campaigns to reclaim the Holy Land were the ones that attracted the greatest support, but the crusading movement's theatre of war extended wider than just Palestine. Crusades were waged in the Iberian Peninsula, northeastern Europe against the Wends, the Baltic region, campaigns were fought against those the church considered heretics in France, Germany, and Hungary, as well as in Italy where popes indulged in armed conflict with their opponents. By definition all the crusades were waged with papal approval and through this reinforced the Western European concept of a single, unified Christian church under the Pope.