The Crusades were a series of military campaigns of a religious character waged by much of Christian Europe against external and internal opponents. Crusades were fought mainly against Muslims, though campaigns were also directed against pagan Slavs, Jews, Russian and Greek Orthodox Christians, Mongols, Cathars, Hussites, Waldensians, Old Prussians and political enemies of the popes.[1] Crusaders took vows and were granted an indulgence for past sins.[1]
The Crusades originally had the goal of recapturing Jerusalem and the Holy Land from Muslim rule and were 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[2] usually against pagans, heretics, and peoples under the ban of excommunication[3] for a mixture of religious, economic, and political reasons.[4] 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.
