This thesis will examine the military orders' role in characterizing frontier life in twelfth and thirteenth century Aragon. This paper contends that the orders' value in the Christian Reconquest of Spain rested more on their exemplification of the Crusade mentality than on their economic acumen or military achievements. By analyzing charters and obligations set forth in grants, agreements, and bequests from this period, this paper will discuss how the orders' unique combination of military and ecclesiastic functions helped to consolidate Aragon's frontier conquests physically and ideologically. Within the context of popular piety symbolized by the cult of Santiago, and efforts by the crown to include resettlement within the religious mission of European crusading movement, this thesis will highlight the role the crusade mentality played in the consolidation of what was perhaps Aragon's most important frontier conquest, the Ebro River Valley, into the Christian community of the Crown of Aragon.