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The First Crusade inspired the Crusading movement which became one of the most significant attributes of late medieval western culture. The movement touched on every area of life, every European country, and the history of the western Islamic world. This influence is evident in the Church, religious thought, politics, the economy, and society. A distinct ideology is evident in the texts that described, regulated, and promoted crusading. The movement defined legal and theological terms based on the theory of Holy War and the concept of pilgrimage. Theologically this merged ideas from Old Testament parallels and Jewish wars that God instigated and assisted, with New Testament Christocentric viewpoints around forming personal relationships with Christ. Crusading as Holy war was based on the ancient idea of just war. The criteria were that a legitimate authority must initiate holy war, that there was just cause and waged with pure intentions. Crusades were special pilgrimages, a physical and spiritual journey under ecclesiastical authority and the protection of the church. Pilgrimage and crusade were penitential acts; popes considered crusaders earned a plenary indulgence giving remission of all God-imposed temporal penalties.
Participants were Christ's soldiers, forming Christ's army. While this was only metaphorical before the first crusade, the concept transferred from the clerical world to secular. Crusaders attached crosses of cloth to their clothing marking them as a follower devotee of Christ, responding to the biblical passage in Luke 9:23 to carry one's cross and follow Christ. The cross symbolized devotion to Christ beyond the penitential exercise. In this way a personal relationship formed between participant and God that marked the participant's spirituality. Anyone could be involved, irrespective of gender, wealth, or social standing. Sometimes this was an imitation of Christ, a sacrifice motivated by charity for fellow Christians. Those who died campaigning were martyrs.
From the beginning, crusading was strongly associated with the recovery of Jerusalem and the Palestinian holy places. The Holy Land was the patrimony of Christ; its recovery was on the behalf of God. The historic Christian significance of Jerusalem as the setting for Christ's act of redemption was fundamental for the First Crusade and the successful establishment of the institution of crusading. Campaigns to the Holy Land met with the greatest enthusiasm and support but crusading was not unique to the Holy Land. By the first half of the 12th century, crusading was transferred to other theatres on the periphery of Christian Europe: the Iberian Peninsula; north-eastern Europe against the Wends; by the 13th century, the missionary crusades into the Baltic region; wars against heretics in France, Germany, and Hungary; and mainly Italian campaigns against the papacy's political enemies. Common to all were Papal sanction and the medieval concept of one Christian community, one church, ruled by the papacy separate from non-believers. Christendom was a geopolitical reference, underpinned by the penitential practice of the medieval church. These ideas grew from the encouragement of the Gregorian Reform of the 11th century and declined after the Reformation. The ideology of crusading continued after the 16th century by the military orders but dwindled in competition with other forms of religious war and new ideologies.
International Relations Theory academic Andrew Latham identified three key pre-conditions that emerged in the 11th century and persisted during the Middle Ages.
The Church's new identity and these developments created structural conflict likely to become violent between the Church and its opponents. The crusades were not only a function anarchy but part of the wider social and political development that differed from the pre-Gregorian Church and other forms of authority. Without these factors, the crusades were impossible and when these factors faded crusading declined.
A Christian theology of war evolved from the point Roman citizenship became linked to Christianity. Christian citizens now had the obligation to fight against the Empire's enemies. The 4th-century theologian Augustine argued that an aggressive war was sinful, but in certain circumstances a "just war" could be rationalized. The criteria were:
These principles formed the basis of a doctrine of holy war that was later developed in the 13th century by Thomas Aquinas, canon lawyers and theologians. Historians, such as Carl Erdmann, thought that from the 10th century the Peace and Truce of God movement restricted conflict between Christians. This movement's influence is apparent in Pope Urban II's speeches, but historians now assert that its influence was limited and had ended by the time of the crusades.
After the collapse of the Carolingian Empire there had been a dramatic increase in piety. Prior to the 11th century the Latin church developed a penitential system that provided remission and absolution of sin in return for contrition, confession, and penitential acts. However, the penance of abstinence from martial activity presented a major challenge to the identity of the noble warrior class. Therefore, it was a revolutionary innovation at the end of the 11th century that provided equal benefits for those who engaged in church sponsored violence as a penitential act.
Gregory VII significantly extended the institutions of holy war and soldiers. It was his loyal supporter Anselm of Lucca who consolidated the just war theories in a single place for the first time, in his 1083 Collectio canonum or Collection of canon law. Gregory offered absolution of sin, via penance. This was earned through violent support of his causes and conditional on the support being given selflessly.
In the 11th century the Church sponsored Christian conflict with Muslims on the southern peripheries of Christendom, including the siege of Barbastro and fighting in Sicily In 1074 he planned a holy war in support of Byzantium's struggles with Muslims, that produced a template for a crusade. This was the first crusade prototype, but Gregory was unable to garner the required support.
Chivalry was in its infancy when the Crusading movement began. There was no heraldry, significant in a largely illiterate society that relied on imagery to impart meaning. Similarly, references in vernacular imagery and song were sparse. No ceremonies existed, and the nobility were reluctant to associate with a knighthood of lesser status in a general militarisation of society.
Before the first crusades, Christian warfare was metaphorically described in Old Testament terms as analogous to the Israelites' conquest of Canaan and the wars of the Maccabees. This presented wars against the enemies of Israel as being waged by God's people, under divine leadership against the enemies of a true religion. Christians believed this sacred warfare was conducted under God's authority and support. Old Testament figures such as Joshua and Judas Maccabaeus were exemplars, and combatants were milites Christi Christ's soldiers forming the militia Christi or Christ's army. With the advent of the crusading movement the concept transferred from the clerical to secular.
Chivalry began to define the ideas and values of knights, who were central to the crusade movement. the original Latin term for an army was Militia and milites described its members. Literature illustrated the prestige of knighthood, but it was distinct from the aristocracy. 11th and 12th century texts depict a class of knights that were closer in status to peasants within recent generations. Only in the 13th century did knighthood became analogous to nobility. Before this the knighthood was not a social class or legal status, anyone could be a knight. Now, the knighthood became increasingly closed to non-nobles. It became an honour and a grade of nobility. Chivalric development grew from a society dominated by the possession of castles. Milites, who defended these, went on to become knights. At the same time a novel form of combat evolved based on the use of the lance, armour instead of chain mail, and short cavalry charges. It was this development of heavy cavalry that combined with the growth of the Italian Maritime republics's navel capability that made the first crusade just about feasible.
The new methods of warfare led to the development of codes, ethics, and ideology. Contrary to the representation in the romances, battles were rare. Instead raids and sieges predominated for which there was only a minimal role for knights. During the eleventh and twelfth centuries the armies consisted in the ratio of one knight to between seven and twelve infantry, mounted sergeants, and squires. Knighthood required a significant combat training which created solidarity and gave rise to combat as sport. From the 12th century tournaments provided knights with practice, sport, wealth, glory, patronage and provided public entertainment. Crusade preachers used tournaments and other similar gatherings to obtain vows of support from attending dignitaries, begin persuasive campaigns and announce a leader's taking of the cross. Capturing opponents to win weapons, armour, horses, or ransom was the objective not killing. This created a moral code out of economic necessity, incorporating a social and religious dimension. Acts of ransom raised considerable sums leading to the ethic that the victors spared defeated knights, but this did not apply to foot soldiers, who were often killed without shame. Military historians such as Hans Delbrück have considered that medieval warfare did not involve good strategy. The decent tactic was considered to be the concentration of force, locating the enemies major force, defeat it in battle and then ruthless enforce supremacy. Medieval institutions were too immature in feudal Europe, with power too fragmented to form disciplined organised units that enacted orders, executed strategy and followed plans. Despite their courage and notable generalship the crusades in the Levant were typically unimpressive. It was only with the adoption of infantry and gunpowder in the 14th century that military strategy improved.
Developing vernacular literature glorified ideas of adventure and virtues of valour, largesse, and courtesy. This created an ideal of the perfect knight as a cultural exemplar. Chivalry was a way of life, a social and moral model which evolved into a myth that conflicted with the ideals of the church. While fearing the knighthood the church co-opted it in conflicts with feudal lords. Writers lauded those who fought for the church, the church excommunicated others. By the 11th century the church developed liturgical blessings sanctifying new knights and existing literary themes, such as the legend of the Grail were Christianized and treatises on chivalry written. In 1100, kings depicted themselves as knights to indicate power. By 1200 all knights were noble. In this cycle crusading entered the culture of western knighthood and participation was considered integral to idealized knightly behaviour. Crusading became part of the knightly class's self-identification, creating a cultural gap with other social classes. From the Fourth Crusade, it became an adventure, normalized in Europe, which altered the relationship between secular motives, devotional warfare and knightly enterprise.
There were significant contributions to the crusading movement from classes other than the nobility and knighthood. Grooms, servants, smiths, armourers, and cooks provided services and could fight if required. Women also formed part of the armies, catering for the soldiers' needs. Despite Papal recruitment in the early years of the movement concentrating on the milites it proved impossible to exclude non-knightly participants. Historians have increasingly researched the motivations of the poor who joined the early crusades in large numbers and engaged in popular unsanctioned events during the 13th and 14th centuries. Participation was voluntary, so preaching needed to propagandise theology in popular forms, that often led to misunderstanding. For example, crusading was technically defensive, but amongst the poor Christianity and Crusading was aggressive. An emphasis on popular preaching developed in the 12th century that generated a wealth of useful resources such as model sermons, manuals of key themes and exemplars. The most popular example is that of Humbert of Romans from 1268. The popular but short-lived outbreaks of crusading enthusiasm after the fall of Acre were largely driven by Eschatological perceptions of crusading amongst the poor rather than the advanced, professionalized plans advocated by theorists.
Pilgrimage was not a mass activity. To develop association with the Holy Sepulchre western Christians built models of the site across Europe and dedicated chapels. Although, this predates crusading, crusading increased the popularity of such acts. These may have provided a backdrop to Easter Drama or sacramental liturgy, it this way what was known as the remotest place in 1099 became embedded in daily devotion, providing a visible sign of what crusading was about.
Ungoverned, uncontrolled peasant crusading erupted in 1096, 1212, 1251, 1309, and 1320. Apart from the historical Children's Crusade of 1212 these were accompanied by violent antisemitism. It is unexplained why this was the exception. The literate classes were hostile to this unauthorized crusade but mythistoricized it so effectively that it is one of the most evocative verbal artefacts from the Middle Ages remaining in European and American imagination. That said, the term “Children's Crusade” requires clarification in that neither children, in Latin pueri or crusade—described in Latin as peregrinatio, iter, expeditio or crucesignatio— is completely wrong, or right. Although there are a significant number of written sources they are of doubtful veracity, differing over dates and details, while exhibiting mythistorical motifs and plotlines. Clerics used the sexual purity and innocence of the pueri as a critique of the sexual misbehaviour in the formal crusades, that was seen to be the source of God's anger and the crusades failure.
In medieval times ethnic identity was a social construct, defined in terms of culture rather than race. The 9th century monk Regino of Prüm wrote the various nations differ from one another in descent, customs, language, and law. Christians considered all of humanity shared common descent from Adam and Eve. Chroniclers used the ethno-cultural terms barbarians or barbarae nations that was inherited from the Greeks in antiquity for others or aliens. In this case it differentiated from the self-descriptive term of Latins that the crusaders used for themselves.
Although there are no specific references to crusading in the 11th century chanson de geste Chanson de Roland the author, intentionally for propaganda purposes, represented Muslims as monsters and idolators. Christian writers repeated this image elsewhere. Visual cues were used to represent Muslims as evil, dehumanized and a monstrous other with black skin pigment and diabolical physiognomies. This portrayal remained current in western literature long after the territorial conflict of the crusades had faded into history. The term Saracen designated a religious community rather than a racial group. The noun Muslim is absent from the chronicles. Instead, various terms are used such as infidels, gentiles, enemies of God, and pagans. The conflict is seen as a Manichean contest between good and evil. Historians have been shocked by the inaccuracy and hostility involved in the representations that included crude insults to Mohammad, caricatures of Islamic rituals and the representation of Muslims as libidinous gluttons, blood thirsty savages and semi-human. Historian Jean Flori argues that to self-justify Christianity's move from pacificism to warfare the enemies needed to be ideologically destroyed.
Despite the negative representations, the Turks were respected as opponents with the Gesta Francorum considering only the Turks and the Franks had knightly lineage. Some, like the character Aumont in the Chanson d’Aspremont, were represented as equals with regards to loyalty, courtesy, and generosity, even as far as being seen as following the Chivalric code. By the Third Crusade there is evident a vertical class division within the nobility in both camps who shared a chivalric identity that overcame religious and political differences. This differentiated the two elites from their common co-religionists who were tied to traditional loyalties. Increasingly epics involved instances of conversion to Christianity which promised a solution to the conflict in favour of the Franks at a time they were being militarily defeated.
Poets often relied on the patronage of leading crusaders, so extoled the values of the nobility, the feudal status quo, chivalry, martial prowess, and the idea of the Holy Land being God's territory, usurped and despoiled. Writers designed works encouraging revenge on Muslims, who deserved punishment and were God's enemies. The artists addressed their works to the patrons, often beginning with Chevalier or Seigneur, based on dialectical understanding of rhetoric in terms of praise or blame. Works praised those who answered the call to crusade, writers blamed those who did not. 
The Reformist church's identity-interest complex framed Islam as a particular form of heresy. Muslim rule in formerly Christian territory was an unjust confiscation of Christian property and this persecution of Christians required repayment, particularly in the Holy Land but also in other territory historically held. The view was that these injustices demanded Christian action and created an irreconcilably hostile relationship between the two faiths. Islamic polities own identity-interest complexes led them to be equally violently opposed to the restoration of Christian rule.
The development of a distinct ideology is evident in the texts that described, regulated, and promoted crusades. The church defined crusading in legal and theological terms based on the theory of Holy War and the concept of pilgrimage. Theology merged Old Testament Jewish wars that were instigated and assisted by God with New Testament Christocentric views on forming individual relationships with Christ. Holy war was based on bellum justum, the ancient idea of just war. It was Augustine of Hippo who Christianized this, and canon lawyers developed it from the 11th century into bellum sacrum, the paradigm of Christian holy war. The papacy developed Political Augustinianism into action to remove the church from secular control and asserting ecclesiastical supremacy over the temporal polities. Reformers considered transformation of clerical behaviour, Christian unity, and doctrinal purity paramount, particularly with regards to relations with the Orthodox church. This was associated with the idea that the church should actively intervene in the secular world to impose justice. In the 12th century, Gratian and the Decretists elaborated on this, and Thomas Aquinas refined it in the 13th century. Theologians widely accepted Henry of Segusio justification that holy war against pagans was just because of their opposition to Christianity. Crusades were special pilgrimages, a physical and spiritual journey under ecclesiastical authority and the protection of the church. Pilgrimage and crusade were penitential acts; popes considered crusaders earned a plenary indulgence giving remission of all God-imposed temporal penalties. In the late 11th and early 12th century the papacy became a unit or organized violence in the Latin world order, equivalent to other kingdoms and principalities. This required the mobilization of secular forces, in addition to the miliary forces directly controlled by the papacy, by mechanisms of control that were slightly inefficient.
Erdmann documented in The Origin of the Idea of Crusade the three stages of the development of a Christian institution of crusade:
It was Odo of Chatillon, who took the name Urban II on his election to the papacy, who initiated the crusading movement with the First Crusade. He became pope at Terracina in March 1088 while the imperialist antipope, Pope Clement III. controlled Rome, and he was unable to enter Rome until 1093 when Clement III withdrew. He made decisions that were fundamental for the nascent religious movements, rebuilding papal authority and restoring its financial position. It was at his most notable council at Clermont in November 1095 he arranged the juristic foundation of the crusading movement with two of its recorded directives: the remission of all atonement for those who journeyed to Jerusalem to free the church and the protection of all their goods and property while doing it. The catalyst was an embassy from the Byzantine Emperor Alexios I Komnenos to the earlier Council of Piacenza, requesting military support in his conflict with the Seljuk Empire. These Turks were expanding into Anatolia and threatening Constantinople. Urban was receptive, having concerns about the Muslim threat to Christendom's eastern borders and hopes to restore unity in the Res publica Christiana. He subsequently expressed the dual objectives for the campaign: firstly, freeing Christians from Islamic rule; secondly, freeing the Holy Sepulchre—the tomb of Christ—in Jerusalem from Muslim control. This led to what is recognised as the first crusading expedition, but he died in July 1099 without knowing that two weeks earlier Jerusalem had been captured.
The description and interpretation of crusading began with accounts of the First Crusade. The image and morality of earlier expeditions served as propaganda for new campaigns. The understanding of the crusades was based on a limited set of interrelated texts. Gesta Francorum or Exploits of the Franks created a papalist, northern French and Benedictine template for later works that contained a degree of martial advocacy that attributed both success and failure to God's will. This clerical view was challenged by vernacular adventure stories based on the work of Albert of Aachen. William of Tyre expanded Albert's writing in his Historia that was completed by 1200. His work described the warrior state the Outremer became as a result of the tension between the providential and the secular. Medieval crusade historiography predominately remained interested in moralistic lessons, extolling the crusades as moral exemplars and cultural norms. Academic crusade historian Paul Chevedden argued that these accounts are anachronistic, it that they were aware of the success of the First Crusade. He argues that to understand the state of the crusading movement in the 11th century it is better to examine the works of Urban II who died unaware of the outcome.
Crusading and chivalry developed symbiotically. The former was effectively the merging of pilgrimage and holy war. The sanctification of war developed during the 11th century through campaigns fought for, instigated, or blessed by the pope including Norman conquest of Sicily, the recovery of Iberia from the Muslims, and the Pisan and Genoese Mahdia campaign of 1087 to North Africa. Crusading followed this tradition, assimilating chivalry within the locus of the church through:
The First Crusade was a military success, but a papal failure. Urban initiated a Christian movement seen as pious and deserving but not fundamental to the concept of knighthood. Crusading did not become a duty or a moral obligation—like pilgrimage to Mecca or Jihad were to Islam. Chivalry remained secular and the creation of military religious orders is indicative of this failure. Canon law forbade priests from warfare, so the orders consisted of a class of lay brothers, but the orders were otherwise remarkably similar institutions to other monastic orders. The difference was that these milites Christi became orders of monks called to the sword and to blood shedding. This was a doctrinal revolution within the church regarding warfare. Its acknowledgement in 1129 at the Council of Troyes integrated the concept holy war into the doctrines of the Latin Church. This illustrated the failure of the church to assemble a force of knights from the laity and the ideological split between crusades and chivalry.
The military vulnerability of the settlers in the East required further supportive expeditions through the 12th and 13th centuries. In each generation, these followed the pattern of a military setback in the East, a request for aid and crusade declarations from the papacy.
The first century of crusading coincided with the Renaissance of the 12th century, and crusading was represented through the rich vernacular literature that evolved in France and Germany during the period. There are French language versions, and in the literary language of southern France—Occitan, of epics such as Chanson d'Antioche about the siege of Antioch and Canso de la Crozada about the Albigensian Crusade. In French these were known as Chansons de geste, taken literally from the Latin for deeds done. Songs dedicated to the subject of crusading—known as Crusade song—are rare, but many works survive in Occitan, French, German, Spanish and Italian from the time of the Second Crusade onwards that include it as a topic or use it as an allegory. Poet-composers such as the Occitan troubadours Marcabru and Cercamon wrote songs with themes called sirventes and about absent loves called pastorela. Crusading became the subject for songs and poems rather than creating new genres. Troubadours, their northern French, Trouvère and German, Minnesänger, equivalents grew in popularity from 1160 leaving many songs about the third and fourth crusades. Crusade songs served multiple purposes:
There is little evidence of protest by senior churchmen, although it is likely that had the first crusades failed this would have been different. The crusades success was astonishing and seen as only possible via a manifestation of God's will, Pope Paschal II described the success as miraculous. Paschal was previously a monk known as Rainerius and had succeeded Urban. He took time to establish his authority, defeating the three anti-popes that followed Clement III and ended the schism in the papacy, but he became embroiled in conflict over the right to invest bishops with Henry V, the Holy Roman Emperor and church reformists led by his eventual successor Guy, archbishop of Vienne (later Pope Calixtus II) . Faced with a revolt of the reformers he revoked concessions made to the emperor. His legislation developed that of his predecessors in connection with crusading. After the failed 1101 crusade, he supported Bohemund of Antioch's gathering of another army with the provision of the flag of St. Peter and a cardinal legate, Bruno of Segni. Relations were fraught between the Latin patriarchate and monarchy of Jerusalem. Paschal organized the Palestine church through three legations led by Maurice of Porto in 1100, Ghibbelin of Arles in 1107 and Berengar of Orange in 1115. By confirming Urban's ruling that the churches in territory won would be held by the successful princes, Paschal ensured ecclesiastical and political borders coincided and settled the dispute between Jerusalem and Antioch over the archbishopric of Tyre. The weakness of conventional theologies in the face of crusading euphoria is shown in a letter from the writer Sigebert of Gembloux criticizing the theory of penitential war that Paschal expressed in a letter to the crusader Robert II, Count of Flanders. Sigebert referred to Robert's safe return from Jerusalem but avoided completely mentioning the crusade.
Calixtus II played a significant role in extending the definition of crusading in his five years as Pope preceding his death in 1124. He was one of the six sons of William I, Count of Burgundy and a distant relation to Baldwin II of Jerusalem. Three of his brothers died taking part in the crusade of 1101. This fact exemplifies that early crusade recruitment concentrated in certain families and networks of vassals. These groups demonstrated their commitment through funding, although the sale of churches and tithes may have been a pragmatic acceptance that retaining these properties wase unsustainable in the face of the reform movement in the church. These kinship groups often exhibited traditions of pilgrimage to Jerusalem, association with Cluniac monastacism, the reformed papacy and the veneration of certain saints. Female relatives spread these values through marriage. The truce Calixtus engineered between Emperor Henry V and the papacy through ratifying the Concordat of Worms at the First Lateran Council in 1123 was the pinnacle of his reign. The council extended the decrees of Urban II and Paschal II promising remission of sin and protection for property and family for crusaders. Additionally, addition he equated the reconquest of Iberia from the Muslims with the crusading to the Holy Land, proposing a war on two fronts, posthumously leading to the campaign by King Alfonso I of Aragon against Granada in 1125.
The crusaders' propensity to follow the customs of their Western European homelands meant that there were very few innovations developed from the culture in the crusader states. Three notable exceptions to this are the military orders, warfare and fortifications. The Knights Hospitaller, formally the Order of Knights of the Hospital of Saint John of Jerusalem, were founded in Jerusalem before the First Crusade but added a martial element to their ongoing medical functions to become a much larger military order. In this way, the knighthood entered the previously monastic and ecclesiastical sphere. Military orders—like the Knights Hospitaller and Knights Templar— provided Latin Christendom's first professional armies to support the Kingdom of Jerusalem and the other crusader states. The Templars, formally the Poor Fellow-Soldiers of Christ and the Temple of Solomon, and their Temple of Solomon were founded around 1119 by a small band of knights who dedicated themselves to protecting pilgrims en route to Jerusalem. These orders became supranational organizations with papal support leading to rich donations of land and revenue across Europe. This led to a steady flow of recruits and the wealth to maintain multiple fortifications in the crusader states. In time, they developed into autonomous powers. After the fall of Acre, the Hospitallers relocated to Cyprus, then conquered and ruled Rhodes (1309–1522) and Malta (1530–1798), and continue in existence to the present-day. King Philip IV of France had financial and political reasons to oppose the Knights Templar, which led to him exerting pressure on Pope Clement V. The pope responded in 1312, with a series of papal bulls including Vox in excelso and Ad providam that dissolved the order on the alleged and false grounds of sodomy, magic, and heresy.
Strategically, the crusaders could not hold Jerusalem in isolation which led to the establishment of other western polities known as the Latin East. Even then these required regular missions for their defence—in 1107/1108 this became a failed assault on the Byzantine Empire, 1120-1125, 1128-1129, and 1139-1140 supported by the developing military orders. The movement expanded into Spain with campaigns in 1114, 1118 and 1122. The Pisan noble Bernard Pignatelli became Pope in 1145 in succession to Lucius II, taking the name Eugenius III. Bernard of Clairvaux influenced him to join the Cistercians. Exiled by an antipapal commune, he encouraged King Louis VII and the French to defend Edessa from the Muslims with bull Quantum predecessores in 1145 and again, slightly amended, in 1146. He clarified Urban's ambiguous position with the view that the crusading indulgence was remission from God's punishment for sin, as opposed to only remitting ecclesiastical confessional discipline. Eugenius commissioned Bernard of Clairvaux to the crusade and travelled to France where he issued Divini dispensatione (II) under the influence of Bernard, associating attacks on the Wends and the reconquest of Spain with crusading. The crusade in the East was not a success and he subsequently resisted further crusading. King Roger II of Sicily enabled his return to Rome in 1149 but he fled Roman politics again until Emperor Frederick Barbarossa enabled his return shortly before his death in 1153. Although there were three campaigns in Spain and in 1177 one in the East the three following decades were the lowest ebb of the movement until the 15th century. This lull ended when news of the defeat at the hands of the Muslims at the Battle of Hattin created consternation throughout Europe and reignited enthusiasm. Early crusades—such as the First, Second and Albigensian—included peasants and non-combatants, until the high costs of journeying by sea made participation in the Third and Fourth Crusade impossible for the general populace. Afterwards, the professional and popular crusades diverged, such as in 1309 when the Crusade of the Poor and one by the Hospitallers occurred simultaneously, both responding to Pope Clement V's crusading summons of the previous year. 
Europeans adopted the terms crucesignatus or crucesignata meaning one signed by the cross from the end of the century with crusaders marking themselves as a follower of Christ by attaching cloth crosses to their clothing. The fashion derived from the biblical passage in Luke 9:23 to carry one's cross and follow Christ. The cross symbolized devotion to Christ and a penitential exercise. Through this action a personal relationship between crusader and God was formed that marked the crusader's spirituality. Anyone could become a crusader, irrespective of gender, wealth, or social standing. Sometimes this was evident as an imitatio Christi or imitation of Christ, or a sacrifice motivated by charity for fellow Christians, while those who died campaigning were martyrs. The Holy Land was the patrimony of Christ; its recovery was on the behalf of God. The Albigensian Crusade was a defence of the French church, the Baltic Crusades were campaigns conquering lands beloved of Christ's mother Mary for Christianity.
Crusade providentialism intricately linked with a prophetic sensibility at the end of the 12th century. Joachim of Fiore included the war against the infidels in his cryptic conflations of history combining past, present, and future, such was his influence Richard I of England met him in Messina en route to the East because, in his view, for this Joachim had the spirit of prophecy and used to foretell what was going to happen. Joachim's view was the new century beginning in 1200 would see the riotous evolution to a third epoch in human history, the age of the Holy Spirit. Foreshadowing the Children's Crusade, the representatives of the third age were children, or pueri. Franciscans such as Salimbene saw themselves as ordo parvulorum— an order of little ones amongst a revivalist enthusiasm and a spirit of prophetic elation. The Austrian Rhymed Chronicle added prophetic elements of mythistory to the Children's Crusade. In 1213 Pope Innocent called the Fifth Crusade by announcing the days of Islam were over: The sway of the beast in Revelations will last 666 years of which already nearly six hundred have passed. The church condemned and suppressed heretics like Amalric of Bena who mixed Gnosticism, antinomianism and pantheism. Only years remained to a prophesised eschatological deadline.
For recruitment purposes, popes initiated each crusade by public preaching of aims, spiritual values, and justification. Preaching could be both authorized and unofficial. The church transmitted news through its hierarchy via a written Papal bull. This system was not always dependable because of conflict among clerics, local political concerns, and lack of education. From the 12th century, the Cistercian Order provided propaganda for campaigns; the Dominicans and Franciscans followed in the 13th century. Mendicant friars and papal legates targeted different geographies. This sophisticated propaganda system was a prerequisite for the success of multiple concurrent crusades. The message varied, but the aim of papal control of crusading remained. Preachers called for Holy Land crusades across Europe, but only preached smaller ventures—e.g., the Northern and Italian crusades—locally to avoid tension in recruitment. Papal authority was critical for the effectiveness of the indulgence and the validity of vow redemption. Aristocratic culture, family networks and feudal hierarchies spread informal propaganda, often by word of mouth. Courts and tournaments were arenas where the population shared stories, songs, poems, news, and information about crusades. Songs of the crusades became increasingly popular, although troubadours were hostile after the Albigensian Crusade. Chivalric virtues of heroism, leadership, martial prowess, and religious fervour were exemplars. Visual representations in books, churches and palaces served the same purpose. Themes expanded in church art and architecture via murals, stained glass windows, and sculptures, such as the windows at the abbey of Saint-Denis, many churches modelled on the Holy Sepulchre at Jerusalem, or murals commissioned by Henry III of England.
There exist greater than fifty texts in Middle English and Middle Scots from around 1225 to 1500 with Crusading themes. Performers delivered these to an audience, as opposed to the audience reading them, for entertainment and as propaganda for a political and religious identity, differentiating the Christian "us" and the non-Christian "other." The works include romances, travelogues such as Mandeville's Travels, poems such as William Langland's Piers Plowman and John Gower's Confessio Amantis, the Hereford Map and the works of by Geoffrey Chaucer. That writers wrote these after crusading fervour had diminished demonstes an ongoing interest. The producers depicted Chivalric Christendom as victorious and superior, holding the spiritual and moral high ground. They originate from translated French originals and adaptations. Some, like Guy of Warwick used the portrayal of Muslim leaders as analogies to critique contemporary politics. Popular motifs include chivalrous Christian knights seeking adventure and fighting Muslim giants or a king travelling in disguise such as Charlemagne in the Scots Taill of Rauf Coilyear. Crusading literature represented legendary figures with military and moral authority. Charlemagne was portrayed as a role model, famed for his victories over the pagan Saxons and Vikings, his religious fervour marked by forced conversion. The entertainment aspect plays a vital role encouraging an element of "Saracen bashing". The literature demonstrates populist religious hatred and bigotry, in part because Muslims and Christians were economic, political, military, and religious rivals while exhibiting a popular curiosity about and fascination with the "Saracens".
Innocent III was elected pope in 1198. He reshaped the ideology and practice of crusading. This was done by creating a new executive office to organize the Fourth Crusade, appointing executors in each province of the church and freelancers preaching, such as Fulk of Neuilly. This system developed further in time for the Fifth Crusade with executive boards established in each province that held Legatine power. Delegates in Dioceses and archdiocese reported to these bodies on promotional policy and the papacy codified preaching. Political circumstance meant that more pragmatic and ad-hoc approaches followed, but the coherence of local promotion remained greater than previously. Innocent III emphasised crusader oaths and penitence and clarified that the absolution of sins was a gift from God, rather than a reward for the crusaders' sufferings. The papacy introduced taxation to fund crusading and encouraged donations. In 1199 he was the first pope to deploy the conceptual and legal apparatus developed for crusading to enforce papal rights. With his 1213 bull Quia maior he appealed to all Christians, not just the nobility, offering the possibility of vow redemption without crusading. This set a precedent for trading in spiritual rewards, a practice that scandalized devout Christians and later became one of the causes of the 16th-century Protestant Reformation. From the 1220s crusader privileges were regularly granted to those who fought against heretics, schismatics or Christians the papacy considered non-conformist.
Part of a tradition of outbreaks of popular crusading enthusiasm that lasted from 1096 until the 1514 Hungarian Peasants' Crusade, the 1212 Children's Crusade was the first independent Popular crusade, beginning amongst the preaching for the Albigensian Crusade and parades seeking God's assistance for Iberian crusades. All crusades not authorized by the church were illicit and unaccompanied by papal representation. Crusades of this type were atypical, and their participants were unconventional crusaders. However, those who took part perceived themselves as authentic crusaders, evident in the use of pilgrimage and crusade emblems, including the cross. Historians describe these events variously as people's crusades, peasants' crusades, shepherds' crusades, and crusades of the poor. Despite a broad range of research topics including social memory, prophecy, crowd psychology, charismatic leadership, social dislocation, religious enthusiasm, and the place of preaching, processions, and visual culture in conveying religious ideology within medieval society, it is difficult for historians to identify common features. There is evidence of charismatic leadership until the 14th century, Eschatology is evident in antisemitic Judaic violence and trends of self-determination amongst the involuntary poor. Popular crusades were diverse but shared historical circumstances with official crusades. These events demonstrate the power of crusading ideas and that non-noble believers were engaged with the momentous events of Latin Christendom. The focus on the activity of clerics and warrior knights underestimates the movement's significance. Cardinal Hugo Ugolino of Segni led a preaching team in Tuscany and northern Italy as papal legate between 1217 and 1221. In this time:
In this way the development of more lax rules on church funding and crusade recruitment is evidenced.  Ugolino became pope in 1227, taking the name Pope Gregory IX and excommunicated Frederick for his prevarication.  Frederick finally arrived in the Holy Land where he negotiated Christian access to Jerusalem, but his claim to the crown through marriage and excommunicate status created political conflict in the kingdom. The settlement was decried by Gregory, but he used the resulting peace to further develop the wider movement:
Gregory was the first pope to deploy the full range of crusading mechanisms such as indulgences, privileges, and taxes against the emperor and extended commutation of crusader vows from expeditions to Outremer to theatres. These measures and the use clerical income tax in the conflict with the emperor formed the foundations for political crusades by Gregory's successor, Innocent IV.
In 1241, after conflict in Lombardy and Sardinia during Frederick II's army threatened Rome. Gregory IX responded with crusading terminology. This was on the grounds that the church viewed Rome as the Patrimony of Saint Peter, and canon law considered crusades as purely defensive wars to protect theoretical Christian territory.
Innocent IV rationalized crusading ideology based on the Christians' right to ownership. He acknowledged Muslims' land ownership but emphasised that this was subject to Christ's authority. Rainald of Segni, who became pope in December 1254 taking the name Alexander IV, continued the policies of Gregory IX and Innocent IV. This meant supporting crusades against the Staufen dynasty, the North African Moors and pagans in Finland and the Baltic region. He attempted to gift Sicily to Edmund Crouchback, son of King Henry III ], in return for a campaign to win it from Manfred, King of Sicily, son of Frederick II, Holy Roman Emperor but this was logistically impossible, and the campaigns were unsuccessful. He offered Theodore II Laskaris, the Greek emperor of Nicaea, the surrender of Latin-held Constantinople and restoration of the Greek Orthodox patriarchate in return for acknowledgment of papal supremacy and the reunion of the Greek and Latin churches. But Theodore died in 1258 and his successor Michael VIII Palaiologos regained Constantinople anyway. Alexander's failed to form a league to confront the Mongols in the East or the invasion of Poland and Lithuania. Frequent crusade calls to fight in eastern Europe (1253–1254, 1259) and Outremer (1260–1261) prompted small forces but his death prevented a general passage.
At the Second Council of Lyons in 1274, Bruno von Schauenburg, Humbert, Guibert of Tournai and William of Tripoli produced treatises articulating the change required for success. Despite criticism, crusading appears to have maintained popular appeal with recruits continuing to take the cross from a wide geographical area. There is evidence of criticism of crusading and the behaviour of crusaders from the beginning of the movement. Although few challenged the concept in the 12th and 13th centuries, there were vociferous objections to crusades against heretics and Christian lay powers. The Fourth Crusade's attack on Constantinople and the use of resources against enemies of the church in Europe, the Albigensian heretics and Hohenstaufen, were all denounced. Troubadours were critical of expeditions in southern France, noting with regret the neglect of the Holy Land. The behaviour of combatants was regarded as inconsistent with that expected of soldiers in a holy war. Chroniclers and preachers complained of sexual promiscuity, avarice, and overconfidence. Western Europeans blamed failures in the First Crusade, the defeat of the kingdom of Jerusalem at Hattin by Saladin of entire campaigns on human sin. Gerhoh of Reichersberg connected that of the Second Crusade to the coming of the Antichrist. Remediation included penitential marches, reformation requests, prohibitions of gambling and luxuries, and limits on the number of women involved. The Würzburg Annals condemned the behaviour of the crusaders and suggested it was the devil's work. Louis IX of France's defeat at the battle of Mansurah provoked doubt and challenge to crusading in sermons and treatises, such as Humbert of Romans's De praedicatione crucis—The preaching of the cross). The cost of armies led to taxation, an idea attacked as an unwelcome precedent by Roger Wendover, Matthew Paris; and Walther von der Vogelweide. Critics raised concern of the Franciscan and Dominican friars abusing the system of vow redemption for financial gain. The peaceful conversion of Muslims was an option, but there is no evidence that this represented public opinion and the continuation of crusading indicates the opposite.
At the end of the 13th century the impending Mamluk victory in the Holy Land left the movement in crisis. Success in Spain, Prussia, and Italy did not compensate for losing the Holy Land. This was a crisis of faith as well as military strategy that the Second Council of Lyon considered religiously shameful. Notable criticism includes Matthew Paris in Chronica majora and the dean of Lincoln at the council. The military orders were disparaged for pride, avarice, devoting their wealth to lives of ease and luxury and not maintaining large enough forces in the Holy Land—particularly the Teutonic Order. Armed conflict between the Templars and Hospitallers and between Christians in the Baltic hindered co-operation. The Church deemed military action in the East less effective because of the independence of the orders and their perceived reluctance to fight the Muslims with whom their critics considered they were on overly friendly terms. Although a minority view held by Roger Bacon and others was that aggression, particularly in the Baltic, impeded conversion.
The crisis did not end with the final fall of the Outremer in 1291 as general opinion did not consider that final. It was only when the Hundred Years' War began in 1337 that recovery hopes faded. However, ideas, and the consolidation of methods of organization and finance following the Council and spanning the decades around 1300 demonstrated qualities of engagement, resilience, and adaptability which in part enabled the movement's survival for generations.
The near three-year interregnum between the death of Pope Clement IV and the 1271 election of Tedaldo Visconti as Pope Gregory X is the longest gap between Popes. One of Gregory's objectives was the reunification of the Greek and Latin churches that he viewed as essential for a new crusade and the Outremer's protection. At the Lyon council beginning in May 1274, he demanded the Orthodox delegation accept all Latin teaching. In return Gregory offered reversal of papal support for Charles I of Anjou, king of Sicily to meet the Byzantines primary motivation of the cessation of Western attacks. However, there was little interest from European monarchs who focussed on their own conflicts. Gregory created a complex tax system, dividing Christendom in 1274 into twenty-six collectorates. Each of these were under the direction of a general collector who further delegated the assessment of tax liability to reduce fraud. Vast amounts raised by this system led to clerical criticism of obligatory taxation.
Even then there were more than twenty treatises on the recovery of the Holy Land between the councils of Lyon in 1274 and Vienna in 1314 prompted by Gregory X and his successors following the example of Innocent III in requesting advice. This advice led to plans for a blockade of the Mamluks, a passigium particulare that provided a bridgehead and a passigium generale by a professional army to follow. Writers debated details through the prism of Capetian and Aragonese dynastic politics. Short lived popular crusading broke out every decade, such as those prompted by the Mongol victory over the Mamluks at Homs and popular crusades in France and Germany. The papacy's institutionalisation of taxation to pay for professional crusading armies on a contractual basis was an extraordinary achievement despite numerous challenges, including a six-year tenth levied on clerical incomes. The 1320 pastores of the Second Shepherds' Crusade was the first time that the papacy decried a popular crusade.
Beginning in 1304 and lasting the entire 14th century, the Teutonic Order used the privileges Innocent IV had granted in 1245 to recruit crusaders in the absence of any formal crusade authority for warfare in Prussia and Livonia. Knightly volunteers from every Catholic state in western Europe flocked to take part in campaigns known as Reisen, or journeys, as part of a Chivalric cult. Commencing in 1332 the numerous Holy Leagues were a new manifestation of the movement in the form of temporary alliances between interested Christian powers. Successful campaigns included the capture of Smyrna in 1344, at the Battle of Lepanto in 1571 and the recovery of territory in the Balkans between 1684 and 1697.
After the Treaty of Brétigny between England and France, the anarchic political situation in Italy prompted the curia to begin issuing indulgences for those who would fight the Routiers threatening the Pope and his court at Avignon. In 1378 Western Schism split the papacy into two and then three rival papacies with rival Popes declaring crusades against each other. The growing threat from the Ottoman Turks provided a welcome distraction that could unite the papacy and divert the violence to another front. By the end of the century the Teutonic Order's Reisen had declined into obsolescence. Commoners had limited interaction with crusading beyond the preaching of indulgences, the success of which depended on the preacher's ability, local powers' attitudes, and the extent of promotion. However, there is no evidence that the failure to organize anti-Turkish crusading was due to popular apathy or hostility rather than finance and politics.
The Venetian, Gabriel Condulmaro, succeeded to Martin V as Eugenius IV in 1431 and developed the policy of ecumenical negotiation with the Byzantines. The visit of large delegation of Byzantines including Emperor John V Palaiologos, the patriarch of Constantinople and seven hundred supporters for talks almost bankrupted him. In 1439 the council moved to Florence, and proclaimed union of the Latin, Greek Orthodox, Armenian, Nestorian, and Cypriot Maronite churches. The Byzantine reward was military support. Between 1440 and 1444 Eugenius IV co-ordinated crusading movements’ defence of Constantinople from the Turks through the Balkan Christians, especially the Hungarian commander John Hunyadi, the Venetian navy, the papacy, and other western rulers. This policy failed with the Balkan powers disastrous defeat at Varna in November 1444. Opponents deposed Eugenius at the Council of Basel in 1439 in favour of Felix V, but they lost support and he was able to continue his policies until his death in 1447. In 1453 the new sultan Mehmed II took Constantinople, ushering in twenty-eight years of the sultanate's expansion.
Humanist Enea Silvio became pope as Pope Pius II in 1458. Constantinople had fallen to the Ottomans in 1453; its recovery was the primary focus of his pontificate. The Congress of Mantua was an unsuccessful blending of crusading with humanist thought to create a European alliance, even though Pius promised to personally participate in the expedition. His famous Latin letters and speeches at Mantua at the Diets of Regensburg and Frankfurt became models of their genre blending humanist styles and thought with Pope Urban II's sermon at Clermont, the First Crusade, the chronicle of Robert of Rheims and Bernard of Clairvaux's letter of exhortation. Besides this he also advised the conqueror of Constantinople to convert to Christianity and become a second Constantine. Pope Pius II came close to organizing an anti-Turkish crusade in 1464 but failed. During his pontificate, and those of his successors, funds and military supplies raised were inadequate, mistimed, or misdirected. This was despite:
Warfare was now more professional and costly. There was disillusionment and suspicion of how practical the objectives of the movement were. Lay sovereigns were more independent and prioritized their own objectives. The political authority of the papacy was reduced by the Great Schism, so popes such as Pius II and Innocent VIII found their congresses ignored. Politics and self-interest wrecked any plans: Venice feared Hungary, Italian states feared Venice, France and Burgundy opposed each other and the German princes believed that any major crusade would lead to a resurgence of imperial authority. All Europe acknowledged the need for a crusade to combat the Ottoman Empire, but effectively all blocked its formation. Popular feeling is difficult to judge. Actual crusading had long since become distant from most commoners’ lives. One example from 1488 saw Wageningen parishioners influenced by their priest's criticism of crusading to such a degree they refused to allow the collectors to take away donations. This contrasts with chronicle accounts of successful preaching in Erfurt at the same time and the extraordinary response for a crusade to relieve Belgrade in 1456.
Rodrigo Borja, who became pope as Pope Alexander VI in 1492, attempted to reignite crusading to counter the threat of the Ottoman Empire, but his secular ambitions for his son Cesare and objective to prevent King Charles VIII of France conquering Naples was paramount. He founded the League of Venice with the Sforza, Republic of Venice, Maximilian I, Holy Roman Emperor and the Spanish to fight the French but his attempts to organize crusading against the Turks came to nothing. The sale of indulgences gained large sums but there was opposition to the clerical tithes and other fund raising to support mercenary crusading armies. The grounds for this were the papacy used these for papal causes in Italy and secular rulers misappropriated funds. Charles VIII's invasion plans prevented the organization of a crusade by Hungary, Bohemia, and Maximilian in 1493 leading instead to Italo-Turkish alliances. Marino Sanuto the Younger, Stephen Teglatius and Alexander himself in Inter caetera wrote of the continued commitment to crusading, the organisational issues, theory, the impact of the Spanish Reconquista completed with the capture of Granada in 1492, the defence and expansion of the faith, and partitioning northern Africa and the Americas between Portugal and Spain the conquest of which he granted crusading privileges and funding. Around the end of the 15th century the military orders were transformed. Castile nationalized its orders between 1487 and 1499. The Hospitallers retreated from Rhodes in 1523 and the Prussian Teutonic Order secularised in 1523.
In the 16th century the rivalry between Catholic monarchs prevented anti-Protestant crusades but individual military actions were rewarded with crusader privileges, including Irish Catholic rebellions against English Protestant rule and the Spanish Armada's attack on Queen Elizabeth I and England. In 1562, Cosimo I de' Medici, Grand Duke of Tuscany became the hereditary Grand Master of the Order of Saint Stephen, a Tuscan military order he founded modelled on the knights of Malta. The Hospitallers remained the only independent military order with a positive military strategy. Other orders continued as aristocratic corporations while lay powers absorbed local orders, outposts, and priories. Teutonic, Portuguese, and Spanish orders continued with limited participation in national military endeavours.
Political concerns provoked self-interested polemics that mixed the legendary and evidential past. Humanist scholarship and theological hostility created an independent historiography. The rise of the Ottomans, the French Wars of Religion, and the Protestant Reformation encouraged the study of crusading. Writers sought redemptive solutions in the military and spiritually penitent traditionalist wars of the cross while others—such as English martyrologist John Foxe—saw these as examples of papist superstition, corruption of religion, papal idolatry, and profanation. Critics blamed the Roman church for the failure of the crusades. War against the infidel was laudable, but not crusading based on doctrines of papal power, indulgences and against Christian religious dissidents, such as the Albigensian and Waldensians. Some Roman Catholic writers considered the crusades gave precedents for dealing with heretics. Both strands thought the crusaders were sincere and were increasingly uneasy in considering war a religious exercise as opposed of having a territorial objective. This secularisation was based on juristic ideas of just war that Lutherans, Calvinists and Roman Catholics could all subscribe, and the role of Indulgences diminished in Roman Catholics tracts on the Turkish wars. Alberico Gentili and Hugo Grotius developed secular international laws of war that discounted religion as a legitimate cause contrasting to popes, who persisted in issuing crusade bulls for generations.
Crusading continued to be evident in the 17th century, mainly associated with the Hapsburgs and Spanish national identity. Crusade indulgences and taxation were used in support of the Cretan War (1645–1669), the Battle of Vienna and the Holy League (1684). Although, the Hospitallers continued the military orders in the 18th century the crusading movement soon ended in terms of acquiescence, popularity, and support.
The French Revolution resulted in widespread confiscations from the military orders who were now largely irrelevant, apart from minor effects in the Hapsburg Empire. The Hospitallers continued acting as a Military Order from its territory in Malta until the island was conquered by Napoleon in 1798. In 1809 Napoleon went on to suppress the Order of St Stephen and the Teutonic Order was stripped of its German possessions before relocating to Vienna. At this point the order's identity as a military order state ended.
Following the inspiration of the first crusades, the Crusading movement significantly defined late medieval western culture and had an enduring impact on the history of the western Islamic world. This influence is evident in every area of life in every country in Europe with evidence in the history of the Church, religious thought, politics, the economy, society and generated and literature. Christendom was a geopolitical reference, and this underpinned the penitential practice of the medieval church. These ideas rose with the encouragement of the reformists of the 11th century and declined after the Reformation. The ideology of crusading continued after the 16th century with the military orders but dwindled in competition with other forms of religious war and new ideologies.
Some historians have maintained that the Kingdom of Jerusalem was the first experiment in western European colonialism, setting up the Outremer as a "Europe Overseas". Certainly by the mid-19th century, the crusader states that had existed in the East were both a nationalist rallying point and emblematic of European colonialism. This is a contentious issue, as others maintain that the accepted definitions of a colony do not fit the Latin settlements in the Levant—that is territory politically directed by, or economically exploited for the benefit of, a homeland, or subject to significant migration. Writers at the time did refer to colonists and migration, this means that academics find the concept of a religious colony is useful, defined as territory captured and settled for religious reasons whose inhabitants maintain contact with their homelands due to a shared faith, and the need for financial and military assistance. That said the crusading movement led directly to the occupation of the Byzantine empire by western colonists after the Fourth crusade. In Venetian Greece, the relationship with Venice and the political and economic direction the city provided matches the more conventional definition of colonialism. In fact, its prosperity and relative safety drained settlers from the Latin East and which weakened the religious colonies of the Levant.
The raising, transportation, and supply of large armies led to a flourishing trade between Europe and the Outremer. The Italian city-states of Genoa and Venice flourished, planting profitable trading colonies in the eastern Mediterranean. The crusades consolidated the papal leadership of the Latin Church, reinforcing the link between the Catholic church, feudalism, and militarism, and increased the tolerance of the clergy for violence. Muslim libraries contained classical Greek and Roman texts that allowed Europe to rediscover pre-Christian philosophy, science and medicine. The growth of the system of indulgences became a catalyst for the Reformation in the early 16th century. The crusades also had a role in the formation and institutionalisation of the military and the Dominican orders as well as of the Medieval Inquisition.
The behaviour of the crusaders in the eastern Mediterranean area appalled the Greeks and Muslims, creating a lasting barrier between the Latin world and the Islamic and Orthodox religions. This became an obstacle to the reunification of the Christian church and fostered a perception of Westerners as defeated aggressors. Many historians argue that the interaction between the western Christian and Islamic cultures played a significant, ultimately positive, part in the development of European civilization and the Renaissance. Relations between Europeans and the Islamic world stretched across the entire length of the Mediterranean Sea, leading to an improved perception of Islamic culture in the West. But this broad area of interaction also makes it difficult for historians to identify the specific sources of cultural cross-fertilisation.
Historical parallelism and the tradition of drawing inspiration from the Middle Ages, have become keystones of political Islam encouraging ideas of a modern jihad and long struggle, while secular Arab nationalism highlights the role of Western imperialism. Muslim thinkers, politicians and historians have drawn parallels between the crusades and modern political developments such as the mandates given to govern Syria, Lebanon, Palestine, and Israel by the United Nations. Right-wing circles in the Western world have drawn opposing parallels, considering Christianity to be under an Islamic religious and demographic threat that is analogous to the situation at the time of the crusades. Advocates present crusader symbols and anti-Islamic rhetoric as an appropriate response, even if only for propaganda. These symbols and rhetoric are used to provide a religious justification and inspiration for a struggle against a religious enemy. Some historians, like Thomas F. Madden, argue that modern tensions result from a constructed view of the crusades created by colonial powers in the 19th century and transmitted into Arab nationalism. For him, the crusades are a medieval phenomenon in which the crusaders were engaged in a defensive war on behalf of their co-religionists.
In 1936, the Spanish Catholic Church baptised and supported the coup of Francisco Franco, declaring a crusade against Marxism and atheism. Thirty-six years of National Catholicism followed during which the idea of Reconquista as a foundation of historical memory, celebration and Spanish national identity became entrenched in conservative circles. Reconquista lost its historiographical hegemony when Spain restored democracy in 1978, but it remains a fundamental definition of the medieval period within conservative sectors of academia, politics, and the media because of its strong ideological connotations.
Main article: Historiography of the Crusades
An independent historiography emerged in the 15th century linked with humanism and theological hostility. This grew in popularity in the 16th century, encouraged by events such as the rise of the Ottoman Turks, the French Wars of Religion, and the Protestant Reformation. Traditional crusading provided exemplars of redemptive solutions that were in turn disparaged as papal idolatry and superstition. War against the infidel was laudable, but crusading movement doctrines were not. Popes persisted in issuing crusade bulls for generations, but secular international laws of war that discounted religion as a legitimate cause were developed. A nationalist view developed providing cultural bridge between the papist past and Protestant future based on two dominant themes for crusade historiography: firstly, intellectual, or religious disdain; secondly, national, or cultural admiration. Crusading now had only a technical impact on contemporary wars but provided imagery of noble and lost causes. Opinions of crusading moved beyond the judgment of religion, and this secularised vision increasingly depicted crusades in good stories or as edifying or repulsive models of the distant past.
18th century Age of Enlightenment philosopher historians narrowed the chronological and geographical scope to the Levant and the Outremer between 1095 and 1291. There were attempts to number crusades at eight while others counted five large expeditions that reached the eastern Mediterranean—1096–1099, 1147–1149, 1189–1192, 1217–1229 and 1248–1254. In the absence of an Ottoman threat influential writers considered crusading in terms of anticlericalism, viewing crusading with disdain for the apparent ignorance, fanaticism, and violence. By 19th century crusade enthusiasts then disagreed with this view as being unnecessarily hostile to, and ignorant. The word "crusade" entered the English language in the 18th century as a hybrid from Spanish, French and Latin.
Increasingly positive views of the Middle Ages developed in the 19th century. A fascination in chivalry developed to support the moral, religious, and cultural mores of the establishment. In a world of unsettling change and rapid industrialization nostalgic, escapist apologists and popular historians developed a positive view of crusading. Jonathan Riley-Smith considers that much of the popular understanding of the crusades derives from the 19th century novels of Sir Walter Scott and the French histories by Joseph François Michaud. MIchaud married admiration with supremacist triumphalism supporting for the nascent European commercial and political colonialism of the time in the Middle East to the point where the Outremer were "Christian colonies". Franco-Syrian society in Outremer became seen as benevolent, an attractive idea during the French mandates in Syria and Lebanon. In 1953 Jean Richard described the kingdom of Jerusalem as "the first attempt by Franks of the West to found colonies". In the absence of widespread warfare, 19th century Europe created a cult of war based on the crusades, linked to political polemic and national identities. After World War I crusading no longer received the same positive responses; war was now sometimes necessary but not good, sanctified, or redemptive. Michaud's viewpoint provoked Muslim attitudes. The crusades had aroused little interest among Islamic and Arabic scholars until the collapse of the Ottoman Empire and the penetration of European power.
Jonathan Riley-Smith straddles the two schools on the actions and motives of early crusaders. The definition of the crusade remains contentious. Historians accept Riley-Smith's view that everyone accepted that the crusades to the East were the most prestigious and provided the scale against which the others were measured. There is disagreement whether it is only those campaigns launched to recover or protect Jerusalem that are proper crusades or whether all those wars to which popes applied equivalent temporal and spiritual were equally legitimate. Today, Crusade historians study the Baltic, the Mediterranean, the Middle East, even the Atlantic, and crusading's position in, and derivation, from host and victim societies. Chronological horizons have crusades existing into the early modern world e.g., the survival of the Order of St. John on Malta until 1798. Academic study of crusading in the West has integrated into mainstream study of theology, the Church, law, popular religion, aristocratic society and values, and politics. The Muslim context now receives attention from Islamicists. Academics have replaced disdain with attempts to locate crusading within its social, cultural, intellectual, economic, and political context. Crusader historians employ wider ranges of evidence, including charters, archaeology, and the visual arts, to supplement chronicles and letters. Local studies have lent precision as well as diversity.