The Crusades were military excursions made by Western European Christians during the late eleventh century through the late thirteenth century. The proclaimed purpose of the Crusades, which were often requested and encouraged by papal policy, was to recover the city of Jerusalem as well as other eastern locations of religious pilgrimage (all located in an area referred to as the Holy Land by Christians) from the control of the Muslims. During the mid-eleventh century, Muslim Turks conquered Syria and Palestine, causing concern among Western Christians. The year 1095 marks the beginning of the Crusades. At this time, Pope Urban II preached a sermon at the Council of Clermont in which he proposed that Western European noblemen and their armies join ranks with the Eastern Christian Byzantine Emperor and his forces in order to mount an attack against the Muslim Turks. Between 1097 and 1099, these combined forces of the First Crusade destroyed the Turkish army at Dorylaeum, conquered the Syrian city of Antioch, and captured Jerusalem. The military achievements of the First Crusade have been attributed to the weak and isolated nature of the Muslim forces. Following the First Crusade, however, they became more united thereby gaining strength, and began attacking the Crusaders' strongholds. In 1145, a Second Crusade was instigated. German and French forces suffered serious casualties and failed to regain the lost ground. After the failed Second Crusade, the Muslim leader Saladin and his Egyptian troops struck many of the Crusaders’ strongholds in 1187; that year, Jerusalem was again captured by Muslim forces. The Third Crusade, proclaimed by Pope Gregory VIII, set out after Jersusalem was taken. This Crusade failed to regain the city; however, Crusaders did manage to conquer some of Saladin's holdings along the Mediterranean coastline. In the early thirteenth century, a Fourth Crusade was organized but was beset with financial troubles, leading to the diversion of the Crusaders from the original destination of Egypt to Constantinople, which was conquered by the Turks. The Fifth Crusade, lasting from 1217 to 1221, attempted to capture Cairo, but failed. In 1228, the excommunicated Holy Roman Emperor Frederick II led a diplomatic campaign to the Holy Land and negotiated a treaty that returned Jerusalem to the Crusaders and offered a ten-year guarantee against attack. After the Muslims recaptured Jerusalem in 1244, King Louis IX of France organized another Middle Eastern expedition, which resulted in his capture in 1250. The strongholds of the Crusaders began to fall to new enemies and despite a few minor expeditions, the crusading movement dwindled to an end.
Critics and historians have approached this period of history in a variety of ways, analyzing the details of the historical records, the literature produced during this time, and the attitudes of Christians toward the Crusades, as well as the forces which influenced people to join the crusading movement. George W. Cox has studied the precursors to the Crusades, demonstrating the relationship between the pilgrimages to the Holy Land that preceded the Crusades and the Crusades themselves. Other critics, such as G. P. R. James, have focused on the history of a particular Crusade. James has analyzed the developments leading to and the events of the Second Crusade, commenting in particular on the social changes that influenced it. Like James, Aziz S. Atiya has concentrated his examination on a specific era of the crusading movement. Atiya argues that the spirit of the Crusades did not die out at the end of the thirteenth century, but continued into the fourteenth and fifteenth centuries. While many critics examine the Crusades from the viewpoint of the Western Christian Crusaders, Robert Lee Wolff and Harry W. Hazard have traced the history of the Crusades from the point of view of the Byzantine empire, examining the contribution of the Byzantine rulers to the military and political developments wrought by the Crusades. Another area of critical interest is the source material from which our knowledge of the Crusades is derived. Oliver J. Thatcher and Steven Runciman are two of the scholars who have evaluated such sources. Thatcher concentrates on the Latin sources, and he assesses the historical value of extant letters and eyewitness accounts. Runciman offers an overview of Greek, Latin, Arabic, Armenian, and Syrian sources.
While Thatcher, Runciman, and others study the contemporary sources of the Crusades for historical accuracy, other critics consider these sources—as well as the poetry, songs, and chronicles of the Crusades—in light of their literary and social value. August C. Krey has studied contemporary accounts of the First Crusade, such as the anonymous Gesta (c. 1099-1101), commenting on the form, content, and style of such works. For example, Krey has observed that the lack of literary allusions and limited vocabulary of the Gesta suggest that the author had acquired a low level of education. Palmer A. Throop has examined the poetry and songs written during the thirteenth century, demonstrating the way in which these verses represent the subtle opposition of their authors to the papal policies on crusading. Similarly, Michael Routledge has analyzed the “crusade songs,” observing in particular the usage of the vernacular in French and German songs of the time. Routledge points to such songs as the entertainment of common and illiterate people during the years of the first four Crusades. The epic poetry of the time is also a source of interest for critics. Alfred Foulet has studied two epic cycles, one written (or at least begun) toward the end of the twelfth century, and the other composed during the 1350s. Foulet discusses the form and content of these epic cycles, notes their similarities, and comments on their literary value. Compared to other contemporary works, such as William of Tyre's Historia rerum in partibus transmarinis gestarum, these epic cycles have little historical value, Foulet maintains. The letters written during the Crusades have also been found by critics to be quite revealing. S. D. Goitein has examined such a letter composed during the summer of 1100. What the letter offers, Goitein explains, is a likely reason for the lack of Jewish narrative on the First Crusade.
Another field of scholarly interest is the search for contemporary evidence of propaganda used to influence the attitudes of Christians toward the Crusades. Dana Carleton Munro has argued that papal sermons and policies encouraged the crusading movement by portraying the Muslims as heathens and worshippers of false gods and idols. Carl Erdmann has studied the development of the crusading movement during the second half of the eleventh century, observing how rhetoric about ecclesiastical aims and warfare became increasingly commingled, which allowed a very general conception of the Crusade to become transformed into the specific form of a Crusade to Jerusalem. Religious forces encouraged the Crusades in another manner as well, observes Colin Morris. The popes, Morris has argued, were aware of the persuasive power of visual imagery, particularly on the illiterate. Therefore, in addition to the preaching of the Crusades in sermons, songs, and liturgy, papal policy encouraged the Crusades through placards carried to advertise a particular Crusade, and through the art and architecture of churches and halls.