The religious wars of the Christian monarchies of Western Europe in the 11th, 12th, and 13th centuries were waged to recover the Holy Land from the Muslims. When he called the First Crusade, Pope Urban II benefited from three facts: (1) the Church had achieved strong independent institutional and public presence in the West; (2) the Byzantine Empire was beginning its decline, in part because of determinedly militaristic Islamic evangelism; and (3) much of life in Western Europe was filtered through a lens of faith and obligation to God and the Church. In service to the faith, European crusaders proceeded to take Jerusalem from the Muslims, in 1099. Postwar events from 1100 onward in the wake of Christian victory provide the frame of reference for the revival of royal (secular) vis-à-vis papal power in Europe.
Begin with two facts: (1) European crusaders were mercenary and repeatedly plundered riches of the east that supposedly exerted a civilizing influence on Europe (spices, silks, culture); and (2) no strategic post-Crusade (nation-building) plans were for the Holy Land. Into the vacuum stepped a host of European nobility who set a pattern for carving out for themselves petty European-style principalities in the Holy Land and in the Balkans as they made their way back and forth across the continent.
Charlemagne's coronation gave papal jurisdiction to the anointing of princes, and creation of the college of cardinals rationalized the method for electing the pope and asserting papal authority over cardinals and bishops in all places. However, the princes began to reason that if the Church anointed pope and princes, an anointed prince should be able to appoint bishops in his own land. Hence the Investiture Controversy, which was characterized by, among other things, factionalism within and between papal, Latin (Roman), and German aristocracies. Such factionalism was implicated in a decline of the Holy Rom
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