There is general agreement among historians on the numbering of the first five crusades: the First Crusade, 1096–1102 CE; Second Crusade, 1147–49 CE; Third Crusade, 1188–92 CE; Fourth Crusade, 1202–04 CE; and Fifth Crusade, 1217–21 CE. Some have argued for the relevance of three additional numbered crusades (the Sixth Crusade, 1227–29 CE; Seventh Crusade, 1248–54 CE; and Eighth Crusade 1270–72 CE)[.]
Particularly notable is the article's revelation that the Crusades were largely financed with the personal wealth of the elite military leaders of the campaigns raised largely through the sale of their real estate.
A variety of sources suggest that the primary crusade participants were members of the European elite—including nobles, knights, and monarchs—as well as the full complement of individuals who might accompany elites on such a journey. Part of the reason that elites were crusade participants was that the costs of raising the funds necessary to participate would be difficult, even for the affluent, and virtually impossible for poor nobles who might be required to raise up to four times their annual income. This is not to say that elites were the numerical majority of travelers to the Holy Land; historians have suggested that nobles and knights in the First Crusade, for example, traveled with at least three to four times their numbers in squires, grooms, and other staff. But it was the elites who “took up the cross” and most of what is known about the crusaders is drawn from charters that document the preparations of elite participants.The abstract and citation to the article are as follows:
Holy Land Crusades were among the most significant forms of military mobilization to occur during the medieval period. Crusader mobilization had important implications for European state formation. We find that areas with large numbers of Holy Land crusaders witnessed increased political stability and institutional development as well as greater urbanization associated with rising trade and capital accumulation, even after taking into account underlying levels of religiosity and economic development. Our findings contribute to a scholarly debate regarding when the essential elements of the modern state first began to appear. Although our causal mechanisms— which focus on the importance of war preparation and urban capital accumulation— resemble those emphasized by previous research, we date the point of critical transition to statehood centuries earlier, in line with scholars who emphasize the medieval origins of the modern state. We also point to one avenue by which the rise of Muslim military and political power may have affected European institutional development.Lisa Blaydes and Christopher Paik, "The Impact of Holy Land Crusades on State Formation: War Mobilization, Trade Integration, and Political Development in Medieval Europe", International Organization / FirstView Article / May 2016, pp 1 - 36 (May 30, 2016).