The Crusades were a series of military conflicts of a religious character waged by much of Christian Europe during 1095–1291, most of which were sanctioned by the Pope of the Roman Catholic Church in the name of the medieval polity of "Christendom."
The Crusades originally had the goal of recapturing Jerusalem and the sacred "Holy Land" from Muslim rule and were originally launched in response to a call from the Eastern Orthodox Byzantine Empire for help against the expansion of the Muslim Seljuk Turks into Anatolia.
The term is also used to describe contemporaneous and subsequent campaigns conducted through to the 16th century in territories outside, the Levant usually against pagans, those considered by the Catholic Church to be heretics, and peoples under the ban of excommunication for a mixture of religious, economic, and political reasons. Rivalries among both Christian and Muslim powers led also to alliances between religious factions against their opponents, such as the Christian alliance with the Sultanate of Rum during the Fifth Crusade.
The Crusades had far-reaching political, economic, and social impacts, some of which have lasted into contemporary times. Because of internal conflicts among Christian kingdoms and political powers, some of the crusade expeditions (such as the Fourth Crusade) were diverted from their original aim and resulted in the sack of a Christian city, Constantinople (finalizing the Great Schism), and the partition of the Byzantine Empire between Venice and the Crusaders. The Sixth Crusade was the first crusade to set sail without the official blessing of the Church, establishing the precedent that rulers other than the Pope could initiate a crusade.
Sword of the Crusader with Scabbard
