The Crusades were a series of religious wars initiated, supported, and sometimes directed by the Latin Church in the medieval period. The term refers especially to the Eastern Mediterranean campaigns in the period between 1095 and 1271 that had the objective of conquering the Holy Land from Islamic rule. The term has also been applied to other church-sanctioned campaigns fought to combat paganism and heresy, to resolve conflict among rival Roman Catholic groups, or to gain political and territorial advantage. The difference between these campaigns and other Christian religious conflicts was that they were considered a penitential exercise that brought forgiveness of sins declared by the church. Historians contest the definition of the term "crusade". Some restrict it to only armed pilgrimages to Jerusalem; others include all Catholic military campaigns with a promise of spiritual benefit; all Catholic holy wars; or those with a characteristic of religious fervour.
In 1095, Pope Urban II proclaimed the First Crusade at the Council of Clermont. He encouraged military support for Byzantine Emperor Alexios I against the Seljuk Turks and an armed pilgrimage to Jerusalem. Across all social strata in western Europe there was an enthusiastic popular response. Volunteers took a public vow to join the crusade. Historians now debate the combination of their motivations, which included the prospect of mass ascension into Heaven at Jerusalem, satisfying feudal obligations, opportunities for renown, and economic and political advantage. Initial successes established four Crusader states in the Near East: the County of Edessa; the Principality of Antioch; the Kingdom of Jerusalem; and the County of Tripoli. The crusader presence remained in the region in some form until the city of Acre fell in 1291, leading to the rapid loss of all remaining territory in the Near East. After this, there were no further crusades to recover the Holy Land.
Proclaimed a crusade in 1123, the struggle between the Christians and Muslims in the Iberian Peninsula was called the Reconquista by Christians, and only ended in 1492 with the fall of the Muslim Emirate of Granada. From 1147 campaigns in Northern Europe against pagan tribes were considered crusades. In 1199 Pope Innocent III began the practice of proclaiming political crusades against Christian heretics. In the 13th century, crusading was used against the Cathars in Languedoc and against Bosnia; this practice continued against the Waldensians in Savoy and the Hussites in Bohemia in the 15th century and against Protestants in the 16th. From the mid-14th century, crusading rhetoric was used in response to the rise of the Ottoman Empire, only ending in 1699 with the War of the Holy League.
In modern historiography, the term "crusade" first referred to military expeditions undertaken by European Christians in the 11th, 12th, and 13th centuries to the Holy Land. The conflicts to which the term is applied has been extended to include other campaigns initiated, supported and sometimes directed by the Roman Catholic Church against pagans, heretics or for alleged religious ends. These differed from other Christian religious wars in that they were considered a penitential exercise, and so earned participants forgiveness for all confessed sins. The term's usage can create a misleading impression of coherence, particularly regarding the early crusades, and the definition is a matter of historiographical debate among contemporary historians.
At the time of the First Crusade, iter, "journey", and peregrinatio, "pilgrimage" were used for the campaign. Crusader terminology remained largely indistinguishable from that of Christian pilgrimage during the 12th century. Only at the end of the century was a specific language of crusading adopted in the form of crucesignatus—"one signed by the cross"—for a crusader. This led to the French croisade—the way of the cross. By the mid 13th century the cross became the major descriptor of the crusades with crux transmarina—"the cross overseas"—used for crusades in the eastern Mediterranean, and crux cismarina—"the cross this side of the sea"—for those in Europe. The modern English "crusade" dates to the early 1700s.
The Arabic word for struggle or contest, particularly one for the propagation of Islam—jihād—was used for a religious war of Muslims against unbelievers, and it was believed by some Muslims that the Quran and Hadith made this a duty. "Franks" and "Latins" were used by the peoples of the Near East during the crusades for western Europeans, distinguishing them from the Byzantine Christians who were known as "Greeks". "Saracen" was used for an Arab Muslim, derived from a Greek and Roman name for the nomadic peoples of the Syro-Arabian desert. Crusader sources used the term "Syrians" to describe Arabic speaking Christians who were members of the Greek Orthodox Church, and "Jacobites" for those who were members of the Syrian Orthodox Church. The Crusader states of Syria and Palestine were known as the "Outremer" from the French outre-mer, or "the land beyond the sea".
Christianity was adopted by the Roman Empire in Late Antiquity and Constantinople was founded by the first Christian Roman Emperor, Constantine the Great, in 324. The city developed into the largest in the Christian world, while the Western Roman Empire collapsed at the end of the 5th century. The city and the Eastern Roman Empire are more generally known as Byzantium, the name of the older Greek city it replaced. By the end of the 11th century the period of Islamic Arab territorial expansion had been over for centuries. Its remoteness from focus of Islamic power struggles enabled relative peace and prosperity for the Holy Land in Syria and Palestine. The conflict in the Iberian peninsula was the only location where Muslim-Western European contact was more than minimal.
The Byzantine Empire and the Islamic world were long standing centres of wealth, culture and military power. They viewed Western Europe as a backwater that presented little organised threat. The Byzantine Emperor Basil II had extended territorial recovery to its furthest extent in 1025. The Empire's frontiers stretched east to Iran. It controlled Bulgaria, much of southern Italy and suppressed piracy in the Mediterranean Sea. The Empire's relationships with its Islamic neighbours were no more quarrelsome than its relationships with the Slavs or the Western Christians. The Normans in Italy; to the north Pechenegs, Serbs and Cumans; and Seljuk Turks in the east all competed with the Empire and the emperors recruited mercenaries—even on occasions from their enemies—to meet this challenge.
After the foundation of the Islamic religion by Muhammad in the 7th century, Muslim Arabs conquered territory from the Indus in the east, and across North Africa and Southern France to the Iberian Peninsula in the West, before political and religious fragmentation halted this expansion. Syria, Egypt, and North Africa were taken from the Byzantine Empire. The emergence of Shia Islam—the belief system that only descendants of Muhammad's cousin and son-in-law, Ali, and daughter, Fatimah, could lawfully be caliph— had led to a split with Sunni Islam on theology, ritual and law. Muslim Iberia was an independent state in modern Spain and Portugal from the 8th century. The Shi'ite Fatimid dynasty ruled North Africa, swathes of Western Asia including Jerusalem, Damascus and parts of the Mediterranean coastline from 969. Total submission to Islam from Jews or Christians was not required. As People of the Book or dhimmi they could continue in their faith on payment of a poll tax. In the Near East a minority Muslim elite ruled over indigenous Christians—Greeks, Armenians, Syrians and Copts.
Waves of Turkic migration into the Middle East enjoined Arab and Turkic history from the 9th century. Prisoners from the borderlands of Khurasan and Transoxania were transported to central Islamic lands, converted to Islam and given military training. Known as ghulam or mamluks, it was expected that as slaves they would be more loyal to their masters. In practice it took these Turks only a few decades to progress from being guards, to commanders, governors, dynastic founders and eventually king makers. Examples include the Tulunids in Egypt and Syria (868–905) and the Ikhshidids who followed in Egypt (935–969).
The political situation in Western Asia was further changed by later waves of Turkish migration. In particular, the arrival of the Seljuk Turks in the 10th century. Previously a minor ruling clan from Transoxania, they had recently converted to Islam and migrated into Iran to seek their fortune. In the two decades following their arrival they conquered Iran, Iraq and the Near East. The Seljuks and their followers were from the Sunni Islamic tradition which brought them into conflict in Palestine and Syria with the Shi'ite Fatimids. The Seljuks were nomadic, Turkish speaking and occasionally shamanistic, very different from their sedentary, Arabic speaking subjects. This difference and the governance of territory based on political preference, and competition between independent princes rather than geography, weakened power structures. Byzantine Emperor Romanos IV Diogenes attempted confrontation in 1071 to suppress the Seljuks sporadic raiding, leading to his defeat at the Battle of Manzikert. Historians once considered this a pivotal event but now Manzikert is regarded as only one further step in the expansion of the Great Seljuk Empire.
The papacy had declined in power and influence to little more than a localised bishopric by the start of the 11th century. But in the period from the 1050s until the 1080s, under the influence of the Gregorian Reform movement, it became increasingly assertive. Conflict with eastern Christians resulted from the doctrine of papal supremacy. The Eastern church viewed the pope as only one of the five patriarchs of the Church, alongside the Patriarchates of Alexandria, Antioch, Constantinople and Jerusalem. In 1054 differences in custom, creed, and practice spurred Pope Leo IX to send a delegation to the Patriarch of Constantinople, which ended in mutual excommunication and an East–West Schism.
The use of violence for communal purposes was not alien to early Christians. The evolution of a Christian theology of war was inevitable when Roman citizenship became linked to Christianity and citizens were required to fight against the Empire's enemies. This was supported by the development of a doctrine of holy war dating from the works of the 4th-century theologian Augustine. Augustine maintained that an aggressive war was sinful, but acknowledged a "just war" could be rationalised if it was proclaimed by a legitimate authority such as a king or bishop, was defensive or for the recovery of lands, and without an excessive degree of violence.
Violent acts were commonly used for dispute resolution in Western Europe, and the papacy attempted to mitigate it. Historians, such as Carl Erdmann, thought the Peace and Truce of God movements restricted conflict between Christians from the 10th century; the influence is apparent in Pope Urban II's speeches. Later historians, such as Marcus Bull, assert that the effectiveness was limited and it had died out by the time of the crusades.
Pope Alexander II developed a system of recruitment via oaths for military resourcing that Gregory VII extended across Europe.  Christian conflict with Muslims on the southern peripheries of Christendom was sponsored by the Church in the 11th century, including the siege of Barbastro and fighting in Sicily In 1074 Gregory VII planned a display of military power to reinforce the principle of papal sovereignty. His vision of a holy war supporting Byzantium against the Seljuks was the first crusade prototype, but lacked support. Theologian Anselm of Lucca took the decisive step towards an authentic crusader ideology, stating that fighting for legitimate purposes could result in the remission of sins.
The first crusade was advocated by Urban II at the Council of Clermont in 1095, promising absolution for the participants' sins. An equivalence was created between crusades for the Holy Land and the Reconquista by Calixtus II in 1123. During the period of the Second Crusade Eugenius III was persuaded by the Cistercian abbot, Bernard of Clairvaux, that the German's conquest of the pagan Slavs was also comparable. The 1146 papal bull Divina dispensatione declared pagan conversion was a goal worthy of crusade. Papal protection, penance and salvation for those killed was extended to participants in the suppression of heretical sects in 1179 during the Third Council of the Lateran.
Elected pope in 1198, Innocent III reshaped the ideology and practice of crusading. He 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. Taxation to fund crusading was introduced and donation encouraged. 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 appealled 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 scandalised 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. When Frederick II's army threatened Rome, Gregory IX used crusading terminology. Rome was seen as the Patrimony of Saint Peter, and canon law regarded crusades as defensive wars to protect theoretical Christian territory.
Innocent IV rationalised crusading ideology on the basis of the Christians' right to ownership. He acknowledged Muslims' land ownership, but emphasised that this was subject to Christ's authority. 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.
The First Crusade was an unexpected event for contemporary chroniclers, but historical analysis demonstrates it had its roots in developments earlier in the 11th century. Clerics and laity increasingly recognised Jerusalem as worthy of penitential pilgrimage. In 1071, Jerusalem was captured by the Turkish warlord Atsiz, who seized most of Syria and Palestine as part of the expansion of the Seljuk Turks throughout the Middle East. The Seljuk hold on the city was weak and returning pilgrims reported difficulties and the oppression of Christians. Byzantine desire for military aid converged with increasing willingness of the western nobility to accept papal military direction.
The desire of Christians for a more effective Church was evident in increased piety. Pilgrimage to the Holy Land expanded after safer routes through Hungary developed from 1000. There was an increasingly articulate piety within the knighthood and the developing devotional and penitential practises of the aristocracy created a fertile ground for crusading appeals. Crusaders' motivations may never be understood. One factor may have been spiritual – a desire for penance through warfare. The historian Georges Duby's explanation was that crusades offered economic advancement and social status for younger, landless sons of the aristocracy. This has been challenged by other academics because it does not account for the wider kinship groups in Germany and Southern France. The anonymous Gesta Francorum talks about the economic attraction of gaining "great booty". This was true to an extent, but the rewards often did not include the seizing of land, as fewer crusaders settled than returned. Another explanation was adventure and an enjoyment of warfare, but the deprivations the crusaders experienced and the costs they incurred weigh against this. One sociological explanation was that crusaders had no choice as they were embedded in extended patronage systems and obliged to follow their feudal lords.
From 1092 the status quo in the Middle East disintegrated following the death of the vizier and effective ruler of the Seljuk Empire, Nizam al-Mulk. This was closely followed by the deaths of the Seljuk Sultan Malik-Shah and the Fatimid khalif, Al-Mustansir Billah. The Islamic historian Carole Hillenbrand has described this as analogous to the fall of the Iron Curtain in 1989 with the phrase "familiar political entities gave way to disorientation and disunity". The confusion and division meant the Islamic world disregarded the world beyond; this made it vulnerable to, and surprised by, the First Crusade.
In 1095, Byzantine Emperor Alexios I Komnenos requested military aid from Pope Urban II at the Council of Piacenza, probably a small body of mercenary reinforcements he could direct and control. Alexios had restored the Empire's finances and authority but still faced numerous foreign enemies. Most significant were the migrating Turks, in particular the Seljuks and their followers, who had colonised the sparsely populated areas of Anatolia. Later that year at the Council of Clermont, Urban raised the issue of military support again and preached for a crusade. Almost immediately, the French priest Peter the Hermit led thousands of mostly poor Christians out of Europe in what became known as the People's Crusade. In transit through Germany these crusaders spawned German bands who massacred Jewish communities in what became known as the Rhineland massacres. This was part of wide-ranging anti-Jewish activities, extending from limited, spontaneous violence to full-scale military attacks. Jews were perceived to be as much an enemy as Muslims: they were held responsible for the crucifixion, and were more immediately visible than the distant Muslims. Many people wondered why they should travel thousands of miles to fight non-believers when there were already non-believers closer to home. The end of the Peoples' Crusade was abrupt. Almost immediately after leaving Byzantine controlled territory on their journey to Nicaea the crusaders were annihilated in a Turkish ambush at the Battle of Civetot.
Conflict with Pope Urban II meant that King Philip I of France and Holy Roman Emperor Henry IV declined to participate in the crusade. But members of the high aristocracy from France, western Germany, the Low Countries, Languedoc and Italy led independent military contingents in loose, fluid arrangements based on bonds of lordship, family, ethnicity and language. Foremost amongst these was the elder statesman, Raymond IV, Count of Toulouse. He was rivalled by the relatively poor but martial Italo-Norman Bohemond of Taranto and his nephew Tancred. They were joined by Godfrey of Bouillon and his brother Baldwin and forces from Lorraine, Lotharingia, and Germany. These five princes were pivotal to the campaign, which was also joined by a northern French army led by: Robert Curthose, Count Stephen II of Blois, and Count Robert II of Flanders. The armies, which may have contained as many as 100,000 people including non-combatants, travelled eastward by land to Byzantium where they were cautiously welcomed by the Emperor. Alexios persuaded many of the princes to pledge allegiance to him; he also convinced them their first objective should be Nicaea, the capital of the Sultanate of Rum. The over-confident Sultan Kilij Arslan left the city to resolve a territorial dispute, thus enabling its capture after a crusader siege and a Byzantine naval assault. This was a high point in Latin and Greek co-operation and the beginning of crusader attempts to take advantage of disunity in the Muslim world.
The first experience of Turkish tactics, using lightly armoured mounted archers, occurred when an advanced party led by Bohemond and Robert was ambushed at Dorylaeum. The Normans resisted for hours before the arrival of the main army caused a Turkish withdrawal. The crusader army marched for three arduous months to the former Byzantine city Antioch, that had been in Muslim control since 1084. Numbers were reduced by starvation, thirst and disease, combined with Baldwin's decision to leave with 100 knights and their followers to carve out his own territory in Edessa which became one of the crusader states. The crusaders besieged Antioch for eight months but lacked the resources to fully invest the city; the residents lacked the means to repel the invaders. Finally, Bohemond persuaded a guard in the city to open a gate. The crusaders entered, massacring the Muslim inhabitants as well as many Christians amongst the Greek Orthodox, Syrian and Armenian communities.
A force to recapture the city was raised by Kerbogha, the effective ruler of Mosul. The Byzantines did not march to the assistance of the crusaders because the deserting Stephen of Blois told them the cause was lost. Instead Alexius retreated from Philomelium, where he received Stephen's report, to Constantinople. The Greeks were never truly forgiven for this perceived betrayal and Stephen was branded a coward. Losing numbers through desertion and starvation in the besieged city, the crusaders attempted to negotiate surrender but were rejected. Bohemond recognised that the only remaining option was open combat and launched a counterattack. Despite superior numbers, Kerbogha's army — which was divided into factions and surprised by the Crusaders commitment and dedication— retreated and abandoned the siege. The crusaders then delayed for months while they argued over who would have the captured territory. The debate ended when news arrived that the Fatimid Egyptians had taken Jerusalem from the Seljuk Turks, making it imperative to attack before the Egyptians could consolidate their position. Bohemond remained in Antioch, retaining the city, despite his pledge to return it to Byzantine control, while Raymond led the remaining crusader army rapidly south along the coast to Jerusalem.
An initial attack on the city failed, and the siege became a stalemate, until the arrival of craftsmen and supplies transported by the Genoese to Jaffa tilted the balance. Crusaders constructed two large siege engines; the one commanded by Godfrey breached the walls. For two days the crusaders massacred the inhabitants and pillaged the city. Historians now believe the accounts of the numbers killed have been exaggerated, but this narrative of massacre did much to cement the crusaders' reputation for barbarism. Godfrey further secured the Frankish position by defeating an Egyptian relief force at Ascalon. Now, most of the crusaders considered their pilgrimage complete and returned to Europe. When it came to the future governance of the city it was Godfrey who took leadership and the title Defender of the Holy Sepulchre. The presence of troops from Lorraine ended the possibility that Jerusalem would be an ecclesiastical domain and the claims of Raymond. At that point Godfrey was left with a mere 300 knights and 2,000 infantry to defend Palestine. Tancred was the other prince who remained. His ambition was to gain a Crusader state princedom of his own. When Godfrey died in 1100 the Lorrainers foiled the attempt of Jerusalem's Patriarch, Daimbert to seize power and enabled Godfrey's brother, Baldwin, to take the crown.
The Islamic world seems to have barely registered the crusade; certainly, there is limited written evidence before 1130. This may be in part due to a reluctance to relate Muslim failure, but it is more likely to be the result of cultural misunderstanding. Al-Afdal Shahanshah, the new vizier of Egypt, and the Muslim world mistook the crusaders for the latest in a long line of Byzantine mercenaries, rather than religiously motivated warriors intent on conquest and settlement. The Muslim world was divided between the Sunnis of Syria and Iraq and the Shi'ite Fatimids of Egypt. Even the Turks remained divided, they had found unity unachievable since the death of Sultan Malik-Shah in 1092, with rival rulers in Damascus and Aleppo. In Baghdad the Seljuk sultan, Barkiyaruq, vied with an Abbasid caliph, Al-Mustazhir, in a Mesopotamian struggle. This gave the Crusaders a crucial opportunity to consolidate without any pan-Islamic counter-attack.
The Crusader states were almost constantly at defensive or expansionist war in the early 12th century. This led to high mortality rates among the nobility as well as a policy of encouraging settlers from the West and Christians from across the Jordan. Bohemond seized Christian cities in Cilicia, refused to return Antioch and in 1108 organised a Crusade against the Byzantine Empire. The Crusade ended in failure after Alexius starved Bohemond of supplies by cutting his supply lines. The resulting Treaty of Devol, although never implemented, forced Bohemond to acknowledge Alexius as his feudal overlord. Relations between Edessa and Antioch were variable: they fought together in the defeat at Battle of Harran, but the Antiocheans claimed suzerainty and attempted to block the return of Count Baldwin—later king of Jerusalem—from his captivity after the battle. This conflict demonstrates the Crusader involvement in Near East politics with Muslims and Christians fighting on both sides. The expansion of Norman Antioch came to an end in 1119 with a major defeat by the Turks at the battle of the Field of Blood.
Under the papacies of successive popes, smaller groups of crusaders continued to travel to the eastern Mediterranean to fight the Muslims and aid the crusader states. The third decade of the 12th century saw campaigns by French nobleman Fulk V of Anjou, the Venetians who captured Tyre, and King Conrad III of Germany, as well as the foundation of the Knights Templar, a military order of warrior monks which became international and widely influential. The Templars, along with the other Military Orders, are estimated to have provided half the military strength of the kingdom of Jerusalem.
For the first time, the rise of Imad ad-Din Zengi saw the Crusaders threatened by a Muslim ruler attempting to restore jihad to Near Eastern politics. After his father was executed for treason in the Seljuk succession crisis little is known of his early years. He became Atabeg of Mosul in 1127 and used this to expand his control to Aleppo and then Damascus. In 1144 he conquered Edessa. After a delay of nearly two years preaching began for what subsequently became known as the Second Crusade. Initially, support was sluggish, partly because Pope Eugenius III delegated the preaching. The French Benedictine abbot, Bernard of Clairvaux spread the message that the loss was the result of sinfulness, and redemption was the reward for crusading. Simultaneously, the anti-Semitic crusade preaching of a Cistercian monk called Rudolf initiated further massacres of Jews in the Rhineland. This formed part of a general increase in crusading activity, including in Iberia and northern Europe.
Zengi was murdered in uncertain circumstances. His elder son Saif ad-Din succeeded him as atabeg of Mosul while a younger son Nur ad-Din succeeded him in Aleppo. For the first time ruling monarchs were campaigning—King Louis VII of France and Conrad III—but the crusade was not a success. Edessa had been destroyed, making its recovery impossible, and the crusade's objectives were unclear. Hostility developed between the French and the Byzantines. The French blamed the Byzantines for defeats suffered against the Seljuks in Anatolia, while the Byzantines laid claims on future territorial gains in northern Syria. As a result, in a decision that historians now criticise, the crusaders attacked the Seljuks of Damascus. This broke a long period of cooperation and coexistence between Jerusalem and Damascus. Bad luck, poor tactics and a feeble five-day siege of Damascus led to internal arguments; the barons of Jerusalem withdrew support and the crusaders retreated before the arrival of a relief army led by Zengi's sons. Morale fell, hostility to the Byzantines grew and distrust developed between the newly arrived crusaders and those that had made the region their home after the earlier crusades.
In 1153 the conquest of Ascalon opened a strategic road south from Palestine and Jerusalem demonstrated an increasing interest in expanding into Egyptian territory. In 1160 King Baldwin III’s planned invasion was only halted by an Egypt tribute payment of 160,000 gold dinars. In 1163 Shawar visited Nur ad-Din in Damascus. He had been deposed as vizier in an outbreak of systemic and murderous Egyptian political intrigue. He wanted political and military support that would aid in regaining the viziership. Nur ad-Din prevaricated, but responded when it became apparent that the crusaders might otherwise gain a strategic foothold on the Nile. Some historians consider this decision a visionary attempt to surround the crusaders. Nur ad-Din provided his Kurdish general, Shirkuh, who stormed Egypt and restored Shawar. However, Shawar asserted his independence. He formed an alliance with Baldwin's brother and successor King Amalric. When Amalric broke the alliance in a ferocious attack, Shawar again requested military support from Syria. Nur ad-Din sent Shirkuh for a second time. Shirkuh was joined by his nephew, Yusuf ibn Ayyub, who became known by his honorific 'Salah al-Din' ('the goodness of faith'), which has been westernised as Saladin. Amalric retreated and Saladin captured and executed Shawar. Saladin successfully intrigued to be appointed vizier in succession to Shirkuh when his uncle died two months later.  Nur ad-Din died in 1174, the first Muslim to unite Aleppo and Damascus in the crusading era. Saladin assumed control and had the strategic choice of establishing Egypt as an autonomous power or attempting to become the pre-eminent Muslim in the eastern Mediterranean; he chose the latter.
While Nur al-Din's territories fragmented, Saladin legitimised his ascent by positioning himself as a defender of Sunni Islam, subservient to both the Caliph of Baghdad and to Nur al-Din's 11-year-old son and successor, As-Salih Ismail al-Malik. He claimed to be the young prince's regent until the boy died seven years later, at which point Saladin seized Damascus and much of Syria but failed to take Aleppo. After building a defensive force to resist a planned attack by the Kingdom of Jerusalem that never materialised, his first contest with the Latin Christians was not a success. Overconfidence and tactical errors led to defeat at the Battle of Montgisard. Despite this setback, Saladin established a domain stretching from the Nile to the Euphrates through a decade of politics, coercion and low-level military action. In 1186 his survival of a life-threatening illness provided the motivation to make good on his propaganda as the champion of Islam. He increased campaigning against the Latin Christians. King Guy responded by raising the largest army that Jerusalem had ever put into the field. Saladin lured the force into inhospitable terrain without water supplies, surrounded the Latins with a superior force, and routed them at the Battle of Hattin. Guy was amongst the Christian nobles taken prisoner, but he was later released. Saladin offered the Christians the option of remaining in peace under Islamic rule or taking advantage of 40 days' grace to leave. As a result of his victory, much of Palestine quickly fell to Saladin, including—after a short five-day siege—Jerusalem. On the 19 October 1187 Pope Urban III died of deep sadness after hearing of the defeat according to Benedict of Peterborough.
Urban III's successor as pope, Gregory VIII, issued a papal bull titled Audita tremendi that proposed what became known as the Third Crusade to recapture Jerusalem. In August 1189, the freed King Guy attempted to recover Acre from Saladin by surrounding the strategic city, only for his own forces to be besieged in turn. Both armies could be supplied by sea, so a long stalemate commenced. The crusaders became so deprived at times they are thought to have resorted to cannibalism. Holy Roman Emperor Frederick I drowned in the Saleph River travelling overland to crusade and few of his men reached their destination. Richard the Lionheart, King of England, travelled by sea. In 1191, he conquered Cyprus when his sister and fiancée were captured by the Cypriot ruler, Isaac Komnenos. Philip II of France was the first king to arrive at the siege of Acre; Richard arrived on 8 June 1191. The arrival of the French and Angevin forces turned the tide in the conflict, and the Muslim garrison of Acre finally surrendered on 12 July. Philip considered his vow fulfilled and returned to France to deal with domestic matters, leaving most of his forces behind. But Richard travelled south along the Mediterranean coast, defeated the Muslims near Arsuf, and recaptured the port city of Jaffa. He twice advanced to within a day's march of Jerusalem. Richard judged that while Saladin had a mustered army he lacked the resources to successfully capture the city or defend it in the unlikely event of a successful assault. This marked the end of Richard's crusading career and was a calamitous blow to Frankish morale. A three-year truce was negotiated that allowed Catholics unfettered access to Jerusalem. Politics in England forced Richard's departure, never to return; Saladin died in March 1193.
In 1198, the recently elected Pope Innocent III announced a new crusade, organised by three Frenchmen: Theobald of Champagne; Louis of Blois; and Baldwin of Flanders. After Theobald's premature death, the Italian Boniface of Montferrat replaced him as the new commander of the campaign. They contracted with the Republic of Venice for the transportation of 30,000 crusaders at a cost of 85,000 marks. However, many chose other embarkation ports and only around 15,000 arrived in Venice. The Doge of Venice Enrico Dandolo proposed that Venice would be repaid with the profits of future conquests beginning with the seizure of the Christian city of Zara. Pope Innocent III's role was ambivalent. He only condemned the attack when the siege started. He withdrew his legate to disassociate from the attack but seemed to have accepted it as inevitable. Historians question whether for him, the papal desire to salvage the crusade may have outweighed the moral consideration of shedding Christian blood. The crusade was joined by King Philip of Swabia, who intended to use the Crusade to install his exiled brother-in-law, Alexios IV Angelos, as Emperor. This required the overthrow of Alexios III Angelos, the uncle of Alexios IV. Alexios IV offered the crusade 10,000 troops, 200,000 marks and the reunion of the Greek Church with Rome if they toppled his uncle Emperor Alexios III.
When the crusade entered Constantinople, Alexios III fled and was replaced by his nephew. The Greek resistance prompted Alexios IV to seek continued support from the crusade until he could fulfil his commitments. This ended with his murder in a violent anti-Latin revolt. The crusaders were without ships, supplies or food leaving them with little option other than to take by force what Alexios had promised. The Sack of Constantinople involved three days of pillaging churches and killing much of the Greek Orthodox Christian populace. While not unusual behaviour for the time, contemporaries such as Innocent III and Ali ibn al-Athir saw it as an atrocity against centuries of classical and Christian civilisation.
The majority of the crusaders considered continuation of the crusade impossible. Many lacked the desire for further campaigning and the necessary Byzantine logistical support was no longer available. The result was that the Fourth Crusade never came within 1,000 miles (1,600 km) of its objective of Jerusalem. Instead it increased Latin territory in the East including Constantinople, demonstrated that poor organisation could wreck an expedition and set a precedent that crusades could legitimately attack not only Muslims but other enemies of the Papacy. A council of six Venetians and six Franks partitioned the territorial gains, establishing a Latin Empire. Baldwin became Emperor of seven-eighths of Constantinople, Thrace, northwest Anatolia and the Aegean Islands. Venice gained a maritime domain including the remaining portion of the city. Boniface received Thessalonika, and his conquest of Attica and Boeotia formed the Duchy of Athens. His vassals, William of Champlitte and Geoffrey of Villehardouin, conquered Morea, establishing the Principality of Achaea. Both Baldwin and Boniface died fighting the Bulgarians, leading the papal legate to release the crusaders from their obligations. As many as a fifth of the crusaders continued to Palestine via other routes, including a large Flemish fleet. Joining King Aimery on campaign they forced al-Adil into a six-year truce.
The Latin states established were a fragile patchwork of petty realms threatened by Byzantine successor states—the Despotate of Epirus, the Empire of Nicaea and the Empire of Trebizond. Thessaloniki fell to Epirus in 1224, and Constantinople to Nicaea in 1261. Achaea and Athens survived under the French after the Treaty of Viterbo. The Venetians endured a long-standing conflict with the Ottoman Empire until the final possessions were lost in the Seventh Ottoman–Venetian War in the 18th century. This period of Greek history is known as the Frankokratia or Latinokratia ("Frankish or Latin rule") and designates a period when western European Catholics ruled Orthodox Byzantine Greeks.
In the 13th century the Mongols became a new military threat to the Christian and Islamic worlds. They defeated the Seljuks and threatened the crusader states while sweeping west from Mongolia through southern Russia, Poland and Hungary. The Mongols were predominately pagans, but some were Nestorian Christians giving the Papacy hope they were possible allies. Saladin's brother Al-Adil supplanted Saladin's sons in the Ayyubid succession, but lacked the authority required to unite the Muslim world of his brother. As a result, the kingdom of Jerusalem revived in a period of peace between 1194 and 1217. in 1213, Innocent III called for another Crusade at the Fourth Lateran Council. In the papal bull Quia maior he codified existing practice in preaching, recruitment and financing the crusades. The plenary indulgence was defined as forgiveness of the sins confessed to a priest for those who fought in, or even provided funding for, crusades. Geoffrey Chaucer's The Pardoner's Tale may demonstrate a cynical view of vow commutation but it was a pragmatic approach that led to more people taking the cross and raising more money in the following century than in the previous hundred years. Innocent died and in 1217 crusading resumed on the expiration of a number of treaties.
A force—primarily raised from Hungary, Germany, Flanders—led by King Andrew II of Hungary and Leopold VI, Duke of Austria achieved little in what is categorised as the Fifth Crusade. The strategy was to attack Egypt because it was isolated from the other Islamic power centres, it would be easier to defend and was self-sufficient in food. Leopold and John of Brienne, the King of Jerusalem and later Latin Emperor of Constantinople, besieged and captured Damietta, but an army advancing into Egypt was compelled to surrender. Damietta was returned, and an eight-year truce agreed.
Holy Roman Emperor Frederick II was excommunicated for frequently breaking an obligation to the pope to join the crusade. In 1225, his marriage to Isabella II of Jerusalem, John of Brienne's daughter and heir, meant he had a claim to the kingdom of Jerusalem. In 1227 he embarked on crusade but was forced to abandon it due to illness but in 1228 he finally reached Acre. Culturally, Frederick was the Christian monarch most empathetic to the Muslim world, having grown up in Sicily, with a Muslim bodyguard and even a harem. Despite his excommunication by Pope Gregory IX, his diplomatic skills meant the Sixth Crusade was largely a negotiation supported by force. A peace treaty granted Latin Christians most of Jerusalem and a strip of territory that linked the city to Acre. The Muslims controlled their sacred sites and an alliance was made with Al-Kamil, Sultan of Egypt, against all his enemies of whatever religion. This treaty, and suspicions about Frederick's ambitions in the region, made him unpopular, and when Pope Gregory IX attacked his Italian domains he was compelled to return and defend them.
The conflict between the Holy Roman Empire and the papacy meant that the responsibility for the campaigns in the Crusader states often fell to secular, rather than papal, leadership. What is known as the Barons' Crusade was led first by Count Theobald I of Navarre and when he returned to Europe, by the king of England's brother, Richard of Cornwall. The death of Sultan al-Kamil and resulting succession conflict in Egypt and Syria allowed the crusaders to follow Frederick's tactics of combining forceful diplomacy with playing rival factions off against each other. Jerusalem was sparsely populated but in Christian hands and the kingdom's territorial reach was the same as before the 1187 disaster at Hattin. This brief renaissance for Frankish Jerusalem was illusory. The Jerusalem nobility rejected the succession of the Emperor's son to the kingdom's throne. The kingdom could no longer rely on the resources of the Holy Roman Empire and was left dependent on Ayyubid division, the crusading orders and other western aid for survival.
The Mongols displaced a central Turkish Asian people, the Khwarazmian, providing Al-Kamil's son As-Salah with useful allies. The Khwarazmians captured Jerusalem and only 300 Christian refugees reached safety at Ramla. A combined Egyptian-Khwarazmian army then defeated a Frankish-Damascene army at the battle of La Forbie. This was the last occasion the Crusader State nobility had the resources to put an army in the field. The Patriarch of Jerusalem put the total losses at 16,000; only 36 out of 348 templars, 26 out of 351 Hospitallers and 3 out 0f 400 Teutonic knights escaped alive.
Thirteenth century politics in the eastern Mediterranean were complex, with numerous powerful and interested parties. The French were led by the very devout Louis IX, king of France, and his ambitiously expansionist brother Charles. Communication with the Mongols was hindered by the enormous distances involved. Louis sent an embassy to the Mongols in Iran in 1249 seeking a Franco-Mongol alliance. When the reply found him in Palestine in 1251 it was again only a demand for tribute. Louis organised a new crusade, called the Seventh Crusade, to attack Egypt, arriving in 1249. He was defeated at Mansura and captured as he retreated to Damietta. Another ten-year truce was agreed. Louis and his nobles were ransomed while the other prisoners were given a choice between conversion to Islam or beheading. He remained in Syria until 1254 to consolidate the crusader states. A brutal power struggle developed in Egypt between various Mamluk leaders and the remaining weak Ayyubid rulers. The Mamluks were slave soldiers that had been used by Muslim rulers for centuries. Most of them were Turks from the Eurasian Steppe or Christians from Anatolia; kidnapped as boys, converted to Islam and given military training. The threat presented by an invasion by the Mongols led to Qutuz seizing the sultanate in 1259 and uniting with another faction led by Baibars to defeat the Mongols at Ain Jalut. The Mamluks then quickly gained control of Damascus and Aleppo before Qutuz was assassinated, most probably by Baibers.
Between 1265 and 1271, Sultan Baibars drove the Franks to a few small coastal outposts. Baibars had three key objectives: to prevent an alliance between the Latins and the Mongols, to cause dissension among the Mongols (particularly between the Golden Horde and the Persian Ilkhanate), and to maintain access to a supply of slave recruits from the Russian steppes. He supported King Manfred of Sicily's failed resistance to the attack of Charles and the papacy. Dissention in the crusader states led to conflicts such as the War of Saint Sabas. Venice drove the Genoese from Acre to Tyre where they continued to trade with Baibars' Egypt. Indeed, Baibars negotiated free passage for the Genoese with Michael VIII Palaiologos, Emperor of Nicaea, the newly restored ruler of Constantinople. In 1270 Charles turned his brother King Louis IX's crusade, known as the Eighth, to his own advantage by persuading him to attack his rebel Arab vassals in Tunis. The crusader army was devastated by disease, and Louis himself died at Tunis on 25 August. The fleet returned to France. Prince Edward, the future king of England, and a small retinue arrived too late for the conflict but continued to the Holy Land in what is known as the Ninth Crusade. Edward survived an assassination attempt, negotiated a ten-year truce, and then returned to manage his affairs in England. This ended the last significant crusading effort in the eastern Mediterranean.
The causes of the decline in crusading and the failure of the crusader states are multi-faceted. The nature of crusades was unsuited to the defence of the Holy Land. Crusaders were on a personal pilgrimage and usually returned when it was completed. Although the ideology of crusading changed over time, crusades continued to be conducted without centralised leadership by short-lived armies led by independently minded potentates, but the crusader states needed large standing armies. Religious fervour was difficult to direct and control even though it enabled significant feats of military endeavour. Political and religious conflict in Europe combined with failed harvests reduced Europe's interest in Jerusalem. The distances involved made the mounting of crusades and the maintenance of communications difficult. It enabled the Islamic world, under the charismatic leadership of Zengi, Nur al-Din, Saladin, the ruthless Baibars and others, to use the logistical advantages of proximity.
The causes of the decline in crusading and the failure of the crusader states are multi-faceted. Historians have attempted to explain this in terms of Muslim reunification and jihadi enthusiasm but Thomas Asbridge, amongst others, considers this too simplistic. Muslim unity was sporadic and the desire for jihad ephemeral. The nature of crusades was unsuited to the conquest and defence of the Holy Land. Crusaders were on a personal pilgrimage and usually returned when it was completed. Although the philosophy of crusading changed over time, the crusades continued to be conducted by short-lived armies led by independently minded potentates, rather than with centralised leadership. What the crusader states needed were large standing armies. Religious fervour enabled significant feats of military endeavour but proved difficult to direct and control. Succession disputes and dynastic rivalries in Europe, failed harvests and heretical outbreaks, all contributed to reducing Latin Europe's concerns for Jerusalem. Ultimately, even though the fighting was also at the edge of the Islamic world, the huge distances made the mounting of crusades and the maintenance of communications insurmountably difficult. It enabled the Islamic world, under the charismatic leadership of Zengi, Nur al-Din, Saladin, the ruthless Baibars and others, to use the logistical advantages of proximity to victorious effect.
The mainland Crusader states were finally extinguished with the fall of Tripoli in 1289 and Acre in 1291. It is reported that many Latin Christians evacuated to Cyprus by boat, were killed or enslaved. Despite this, Ottoman census records of Byzantine churches show that most parishes in the former Crusader states survived at least until 16th-century and remained Christian.
After the First Crusade most of the crusaders considered their personal pilgrimage complete and returned to Europe. Modern research indicates that Muslim and indigenous Christian populations were less integrated than previously thought. Palestinian Christians lived around Jerusalem and in an arc stretching from Jericho and the Jordan to Hebron in the south. Archaeological research on Byzantine churches and Ottoman census records from the 16th century demonstrate that Greek Orthodox communities survived centuries after the fall of the Crusader states. Maronites were concentrated in Tripoli, the Jacobites in Antioch and Edessa. Armenians also lived in the north but communities existed in all major towns. Central areas had a Muslim majority population, predominantly Sunni but with Shi'ite communities in Galilee. Druze Muslims lived in the mountains of Tripoli. The Jewish population resided in coastal towns and some Galilean villages. The Frankish population of the Kingdom of Jerusalem was concentrated in three major cities. By the 13th century the population of Acre probably exceeded 60,000, then came Tyre and the capital itself was the smallest of the three with a population somewhere between 20,000 and 30,000. The Latin population of the region peaked at c250,000 with Jerusalem's population numbering c120,000 and the combined total in Tripoli, Antioch and Edessa being broadly comparable. In context, Josiah Russell roughly estimates the population of what he calls "Islamic territory" as 12.5 million in 1000 with the European areas that provided crusaders having a population of 23.7 million. He estimates that by 1200 that these figures had risen to 13.7 million in Islamic territory while the Crusaders' home countries population was 35.6 million. Russell acknowledges that much of Anatolia was Christian or under the Byzantines and "Islamic" areas such as Mosul and Baghdad had significant Christian populations.
The Outremer was a frontier society in which a Frankish elite ruled over of a native population related to the neighbouring communities, many of whom were hostile to the Franks. It was politically and legally stratified with self-governing ethnic communities. Relations between communities were controlled by the Franks. The basic division in society was between Frank and non-Frank, and not between Christian and Muslim. All Franks were considered free men while the native peoples lived like western serfs. The Franks imposed officials in the military, legal and administrative systems using the law and lordships to control the natives. Few Franks could speak more than basic Arabic. Dragomans—interpreters—and ruʾasāʾ—village headmen—were used as mediators. Civil disputes and minor criminality were administered by the native communities, but major offences and those involving Franks were dealt by the Frankish cour des bourgeois. The key differentiator in status and economic position was between urban and rural dwellers. Indigenous Christians could gain higher status and acquire wealth through commerce and industry in towns but few Muslims lived in urban areas except servants.
The Crusader States presented an obstacle to Muslim trade with the west by sea and the land routes from Mesopotamia and Syria to the urban economies of the Nile. However, despite this commerce continued, coastal cities remained maritime outlets for the Islamic hinterland, Eastern wares were exported to Europe in unprecedented volumes. Byzantine-Muslim mercantile growth in the 12th and 13th centuries may have occurred anyway. Western Europe's population, wealth and the demand for sophisticated Eastern products was booming but it is likely that the Crusades hastened the developments. European fleets expanded, better ships were built, navigation improved and fare paying pilgrims subsidised many voyages. The mainly native agricultural production flourished before the fall of the First Kingdom in 1187, but was negligible afterwards. Italian, Provençal and Catalan merchants monopolised shipping, imports, exports, transportation and banking while the income of the Franks was based on income from estates, market tolls and taxation. Production centred in Antioch, Tripoli, Tyre and Beirut. The Franks exported textiles, glass dyestuffs, olives, wine, sesame oil, sugar and prized Silk and imported clothing and finished goods. The indigenous monetised economic system was adopted with northern Italian and southern French silver European coins, Frankish copper coins minted in Arabic and Byzantine styles, local silver and gold dirhams and dinars. After 1124, Egyptian dinars were copied creating Jerusalem's gold bezant. Following the collapse of the First Kingdom in 1187, trade rather than agriculture increasingly dominated the economy and western coins dominated the coinage and despite some local minting of silver pennies and coppers there is little evidence of systematic attempts to create a unified local currency.
During the near constant warfare in the early decades of the 12th century, the king of Jerusalem's foremost role was leader of the feudal host. They rewarded their followers' loyalty with city incomes rarely granting land and when holdings became vacant, due to the conflict's high mortality rate this reverted to the crown. The result was that the royal domain of the first five rulers was greater than the combined holdings of the nobility. This gave the rulers of Jerusalem greater internal power than comparative western monarchs but without the necessary administrative machinery to govern a large realm. Baronial dynasties evolved in the second quarter of the century often acting as autonomous rulers. Royal powers were abrogated and effectively governance undertaken locally within the feudatories. Central control that remained was exercised through the Haute Cour or High Court. This was meetings between the king and his tenants in chief. The duty of the vassal to give counsel became a privilege until the legitimacy of the monarch depended on the agreement of the court. The barons have been poorly regarded by both contemporary and modern commentators who note their superficial rhetoric, pedantry and spurious legal justification for political action.
The High Court consisted of the great barons and the king's direct vassals with a quorum of the king and three tenants in chief. The 1162 Assise sur la ligece expanded membership to all the 600+ Franks who paid homage directly to the king. They were joined by the heads of the military orders before the end of the 12th century and the Italian communes in the 13th century. Before the defeat at Hattin in 1187 the laws developed were documented as Assises in Letters of the Holy Sepulchre. The entire body of written law was lost in the fall of Jerusalem leaving a legal system largely based on the custom and memory of the lost legislation. Philip of Novara wrote
We know [the laws] rather poorly, for they are known by hearsay and usage...and we think an assize is something we have seen as an assize...in the kingdom of Jerusalem [the barons] made much better use of the laws and acted on them more surely before the land was lost
A myth was created of an idyllic early 12th century legal system that the barons used to reinterpret the Assise sur la ligece that Almalric I intended to strengthen the crown to rather than constrain the monarch's ability to confiscate feudal fiefs without trial. When the rural fiefs were lost the barons became an urban mercantile class whose knowledge of the law was a valuable skill and career path to higher status. The leaders of the Third Crusade considered the monarchy of Jerusalem of secondary importance. They decided on the grants of land and even granted the throne itself in 1190 and 1192, to Conrad of Montferrat and Henry II, Count of Champagne. Emperor Frederick II married Queen Isabella in 1225 and claimed the throne from her father, the King Regent—John of Brienne. In 1228 Isabella II died after giving birth to a son, Conrad, who through his mother was now legally king of Jerusalem and Frederick's heir. Frederick II left the Holy Land to defend his Italian and German lands beginning a period of absent monarchs from 1225 until 1254. In contrast to Western monarchies with powerful, with centralised bureaucracies government in Jerusalem developed in the opposite direction. Jerusalem's royalty had title but little power. Magnates fought for regency control with an Italian army led by Frederick's viceroy Richard Filangieri in the War of the Lombards. Tyre, the Hospitallers, the Teutonic Knights and Pisa supported Filangieri. In opposition were the Ibelins, Acre, the Templars and Genoa. For twelve years the rebels held a surrogate parliament in Acre before prevailing in 1242, leading to a succession of Ibelin and Cypriot regents . Centralised government collapsed and the nobility, military orders and Italian communes took the lead. Three Cypriot Lusignan kings succeeded without the resources to recover the lost territory. The title of king was sold to Charles of Anjou who gained power for a short while but never visited the kingdom. 
The early crusaders filled ecclesiastical positions left vacant by the Orthodox church and replaced Orthodox bishops with Latin clerics. The Greek Orthodox monks of the Holy Sepulchre were expelled but recalled when the miracle of Easter Fire failed in their absence. Armenians, Copts, Jacobites, Nestorians and Maronites were considered autonomous, retaining their own bishops.
Largely based in the ports of Acre, Tyre, Tripoli and Sidon, Italian, Provençal and Catalan communes had distinct cultural characteristics and exerted significant political power. Separate from the Frankish nobles or burgesses, the communes were autonomous political entities closely linked to their hometowns. They monopolised foreign trade and almost all banking and shipping and aggressively extended trade privileges. Despite all efforts, the ports were unable to supersede Alexandria and Constantinople as the primary regional commercial centres but the communes did compete with the monarchs and each other for economic advantage. Power derived from the support of the communards' native cities rather than their number, which never reached more than hundreds. By the middle of the 13th century, the rulers of the communes barely recognised crusader authority and divided Acre into several fortified miniature republics.
There were few cultural innovations in the Outremer beyond the establishment of the military orders and the development of tactics and military architecture. John of Ibelin records in around 1170 that the military force of the kingdom of Jerusalem was based on a feudal host of about 647 to 675 heavily armoured knights. Each knight would also provide his own armed retainers. Non-noble light cavalry and infantry were known as serjants and these numbered around 5,025. These numbers were augmented by mercenaries such as the Turcopoles recruited from among the natives.  Joshua Prawer estimated that the military orders matched this force in number giving an estimated military strength of 1,200 knights and 10,000 serjants. This was sufficient for territorial gains, but fewer than the required to maintain military domination. This defensive problem was that putting an army into the field required draining castles and cities of every able-bodied fighting man. In the case of a defeat such as at Hattin, no one remained to resist the invaders. The Franks adopted delaying tactics when faced with a superior invading Muslim force, avoiding direct confrontation, retreating to strongholds and waiting for the Muslim army to disperse. Muslim armies were incohesive and seldom campaigned beyond a period between sowing and harvest. It took generations before the Muslims identified that in order to conquer the Crusader states they needed to destroy the Frankish fortresses. This strategic change forced the crusaders away from focussing on the gaining and holding territory but rather on attacking and destroying Egypt, neutralising this regional challenge and gaining the time to improve the kingdom's demographic weaknesses.
The disintegration of the Caliphate of Córdoba in southern Spain created the opportunity for the Reconquista, beginning in 1031. The Christian realms had no common identity or shared history based on tribe or ethnicity. As a result, León, Navarre and Catalonia united and divided several times during the 11th and 12th centuries. Although small, all developed an aristocratic military technique. By the time of the Second Crusade the three kingdoms were powerful enough to conquer Islamic territory—Castile, Aragon and Portugal. In 1212 the Spanish were victorious at the Battle of Las Navas de Tolosa with the support of 70,000 foreign combatants who responded to the preaching of Innocent III. Many foreigners deserted because of the tolerance the Spanish demonstrated for the defeated Muslims. For the Spanish, the Reconquista was a war of domination rather than a war of extermination. This contrasted with the treatment of the Christians formerly living under Muslim rule, the Mozarabs. The Roman Rite was relentlessly imposed on them, and the native Christians were absorbed into mainstream Catholicism. Al-Andalus, Islamic Spain, was completely suppressed in 1492 when the Emirate of Granada surrendered. At this point the remaining Muslim and Jewish inhabitants were expelled from the peninsula.
There were modest efforts to suppress a dualistic Christian sect called the Cathars in southern France around 1180. After a thirty-year delay Innocent III proclaimed the Albigensian Crusade, named after the city of Albi, one of the centres of Catharism. This proved that it was more effective waging a war against the heretics' supporters than the heretics themselves. Tolerant feudal lords had their lands confiscated and titles forfeited. In 1212 pressure was exerted on the city of Milan for tolerating Catharism. Two Hungarian invasions of Bosnia, the home of a legendary Cathar anti-pope, were proclaimed crusades in 1234 and 1241. A crusade forced the Stedinger peasants of north-western Germany to pay tithes in 1234. The historian Norman Housley notes the connection between heterodoxy and anti-papalism in Italy. Indulgences were offered to anti-heretical groups such as the Militia of Jesus Christ and the Order of the Blessed Virgin Mary. Anti-Christian crusading declined in the 15th century, the exceptions were the six failed crusades against the religiously radical Hussites in Bohemia and attacks on the Waldensians in Savoy.
The Albigensian Crusades established a precedent for popes and the Inquisition to claim their Christian opponents were heretics. Innocent III declared the first political crusade against Markward von Annweiler, the regent for Frederick II. Later, when Frederick threatened to take Rome in 1240, Gregory IX used crusading terminology to raise support against him. On Frederick II's death the focus moved to Sicily. In 1263, Pope Urban IV offered crusading indulgences to Charles of Anjou in return for Sicily's conquest. But, these wars had no clear objectives or limitations making them unsuitable for crusading. The 1281 election of a French pope, Martin IV, brought the power of the papacy behind Charles. Charles's preparations for a crusade against Constantinople were foiled by the Byzantine Emperor Michael VIII Palaiologos, who instigated an uprising called the Sicilian Vespers. Instead, Peter III of Aragon was proclaimed king of Sicily, despite his excommunication and an unsuccessful Aragonese Crusade. Political crusading continued against Venice over Ferrara; Louis IV, King of Germany when he marched to Rome for his imperial coronation; and the free companies of mercenaries.
In 1147 Bernard of Clairvaux persuaded Pope Eugenius III that the Germans' and Danes' conflict with the pagan Wends was a holy war analogous to the Reconquista; he urged a crusade until all heathens were baptised or killed. The new crusaders' motivation was primarily economic: the acquisition of new arable lands and serfs; the control of Baltic trade routes; and the abolishment of the Novgorodian merchants' monopoly of the fur trade. From the early 13th century the military orders provided garrisons in the Baltic and defended the German commercial centre, Riga. The Livonian Brothers of the Sword and the Order of Dobrzyń were established by local bishops. The Sword Brothers were notorious for cruelty to pagans and converts alike. The Teutonic Knights were founded during the 1190s in Palestine, but their strong links to Germany diverted efforts from the Holy Land to the Baltic. Between 1229 and 1290, the Teutonic Knights absorbed both the Brothers of the Sword and the Order of Dobrzyń, subjugated most of the Baltic tribes and established a ruthless and exploitative monastic state. The Knights invited foreign nobility to join their regular Reisen, or raids, against the last unconquered Baltic people, the Lithuanians. These were fashionable events of chivalric entertainment among young aristocrats. Jogaila, Grand Prince of Lithuania, converted to Catholicism and married Queen Jadwiga of Poland resulting in a united Polish–Lithuanian army routing the Knights at Tannenberg in 1410. The Knights' state survived, from 1466 under Polish suzerainty. Prussia was transformed into a secular duchy in 1525, and Livonia in 1562.
The Seljuk Sultanate of Rum fragmented in the late 13th century. The Ottoman Turks, located in north-eastern Anatolia, took advantage of a Byzantine civil war of 1341–1347 and established a strong presence in Europe. They captured the Byzantine fortress at Gallipoli in 1354 and defeated the Serbians at the Battle of Kosovo in 1389, winning control of the Balkans from the Danube to the Gulf of Corinth. This was further confirmed by victory over French crusaders and King Sigismund of Hungary at the Battle of Nicopolis in 1396. Sultan Murad II destroyed a large crusading Serbian and Hungarian force at Varna in 1444 and four years later defeated the Hungarians at Kosovo again.
After the fall of Constantinople in 1453 the crusading response was largely symbolic. One example was Duke Phillip of Burgundy's 1454 promotion of a crusade, that never materialised, at the Feast of the Pheasant. The 16th century saw growing rapprochement. The Habsburgs, French, Spanish and Venetians all signed treaties with the Ottomans. King Francis I of France sought allies from all quarters, including from German Protestant princes and Sultan Suleiman the Magnificent. Crusading became chiefly a financial exercise with precedence given to the commercial and political aspects. As the military threat presented by the Turks diminished, anti-Ottoman crusading became obsolete with the Holy League in 1699.
The crusaders' propensity to follow the customs of their Western European homelands meant that there were few innovations developed in the crusader states. Three notable exceptions to this were the military orders, warfare and fortifications. The Knights Hospitaller, formally the Order of Knights of the Hospital of Saint John of Jerusalem, had a medical function in Jerusalem before the First Crusade. The order later adding a martial element and became a much larger military order. In this way knighthood entered the previously monastic and ecclesiastical sphere. The Templars, formally the Poor Fellow-Soldiers of Christ and the Temple of Solomon were founded around 1119 by a small band of knights who dedicated themselves to protecting pilgrims en route to Jerusalem. King Baldwin II granted the order the Al-Aqsa Mosque in 1129 they were formally recognised by the papacy at the 1129 Council of Troyes. Military orders like the Knights Hospitaller and Knights Templar provided Latin Christendom's first professional armies in support of the Kingdom of Jerusalem and the other crusader states.
The Hospitallers and the Templars became supranational organisations as papal support led to rich donations of land and revenue across Europe. This, in turn, led to a steady flow of new recruits and the wealth to maintain multiple fortifications in the crusader states. In time, they developed into autonomous powers in the region. After the fall of Acre the Hospitallers relocated to Cyprus, then ruled Rhodes until the island was taken by the Ottomans in 1522, and Malta until Napoleon captured the island in 1798. The Sovereign Military Order of Malta continues in existence to the present-day. King Philip IV of France probably 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, explaining that the order has been defamed by accusations of sodomy, heresy and magic, although he did not condemn it on theses contested charges.
According to the historian Joshua Prawer no major European poet, theologian, scholar or historian settled in the crusader states. Some went on pilgrimage, and this is seen in new imagery and ideas in western poetry. Although they did not migrate east themselves, their output often encouraged others to journey there on pilgrimage.
Historians consider the crusader military architecture of the Middle East to demonstrate a synthesis of the European, Byzantine and Muslim traditions and to be the most original and impressive artistic achievement of the crusades. Castles were a tangible symbol of the dominance of a Latin Christian minority over a largely hostile majority population. They also acted as centres of administration. Modern historiography rejects the 19th-century consensus that Westerners learnt the basis of military architecture from the Near East, as Europe had already experienced rapid development in defensive technology before the First Crusade. Direct contact with Arab fortifications originally constructed by the Byzantines did influence developments in the east, but the lack of documentary evidence means that it remains difficult to differentiate between the importance of this design culture and the constraints of situation. The latter led to the inclusion of oriental design features such as large water reservoirs and the exclusion of occidental features such as moats.
Typically, crusader church design was in the French Romanesque style. This can be seen in the 12th-century rebuilding of the Holy Sepulchre. It retained some of the Byzantine details, but new arches and chapels were built to northern French, Aquitanian and Provençal patterns. There is little trace of any surviving indigenous influence in sculpture, although in the Holy Sepulchre the column capitals of the south facade follow classical Syrian patterns.
In contrast to architecture and sculpture, it is in the area of visual culture that the assimilated nature of the society was demonstrated. Throughout the 12th and 13th centuries the influence of indigenous artists was demonstrated in the decoration of shrines, paintings and the production of illuminated manuscripts. Frankish practitioners borrowed methods from the Byzantines and indigenous artists and iconographical practice leading to a cultural synthesis, illustrated by the Church of the Nativity. Wall mosaics were unknown in the west but in widespread use in the crusader states. Whether this was by indigenous craftsmen or learnt by Frankish ones is unknown, but a distinctive original artistic style evolved.
Manuscripts were produced and illustrated in workshops housing Italian, French, English and local craftsmen leading to a cross-fertilisation of ideas and techniques. An example of this is the Melisende Psalter, created by several hands in a workshop attached to the Holy Sepulchre. This style could have both reflected and influenced the taste of patrons of the arts. But what is seen is an increase in stylised, Byzantine-influenced content. This extended to the production of icons, unknown at the time to the Franks, sometimes in a Frankish style and even of western saints. This is seen as the origin of Italian panel painting. While it is difficult to track illumination of manuscripts and castle design back to their origins, textual sources are simpler. The translations made in Antioch are notable, but they are considered of secondary importance to the works emanating from Muslim Spain and from the hybrid culture of Sicily.
Until the requirement was abolished by Innocent III married men needed to obtain their wives' consent before taking the cross, which was not always readily forthcoming. Muslim and Byzantine observers viewed with disdain the many women who joined the armed pilgrimages, including female fighters. Western chroniclers indicated that female crusaders were wives, merchants, servants and sex workers. Attempts were made to control the women's behaviour in ordinances of 1147 and 1190. Aristocratic women had a significant impact: Ida of Formbach-Ratelnberg led her own force in 1101; Eleanor of Aquitaine conducted her own political strategy; and Margaret of Provence negotiated her husband Louis IX's ransom with an opposing woman—the Egyptian sultana Shajar al-Durr. Misogyny meant that there was male disapproval; chroniclers tell of immorality and Jerome of Prague blamed the failure of the Second Crusade on the presence of women. Even though they often promoted crusading, preachers would typecast them as obstructing recruitment, despite their donations, legacies and vow redemptions. The wives of crusaders shared their plenary indulgences.
The crusades, like all military endeavours of the time were costly enterprises. Payment to participants contributed to order and discipline, was not in conflict with religious motivation and prompted innovative initiatives for the funding of campaigns. Property was sold or mortgaged; taxation was raised at estate, clerical and national level; and charges were made for vow redemption. Money was also borrowed, extorted and stolen from Jewish commuinities.
The military expeditions undertaken by European Christians in the 11th, 12th, and 13th centuries to recover the Holy Land from Muslims provided a template for warfare in other areas that also interested the Latin Church. These included the 12th and 13th century conquest of Muslim Al-Andalus by Spainish Christian kingdoms; 12th to 15th century German Northern Crusades expansion into the pagan Baltic region; the suppression of non-conformity, particularly in Languedoc during what has become called the Albigensian Crusade and for the Papacy's temporal advantage in Italy and Germany that are now known as political crusades. In the 13th and 14th centuries there were also unsanctioned, but related popular uprisings to recover Jerusalem known variously as Shepherds' or Children's crusades.
The Crusades created national mythologies, tales of heroism, and a few place names. 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 a centuries-long struggle against Christian states, while secular Arab nationalism highlights the role of western imperialism. Modern Muslim thinkers, politicians and historians have drawn parallels between the crusades and political developments such as the establishment of Israel in 1948. 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. Crusader symbols and anti-Islamic rhetoric are presented as an appropriate response. These symbols and rhetoric are used to provide a religious justification and inspiration for a struggle against a religious enemy. Many modern anti-immigrant and white supremacist groups, in Europe and North America, make explicit associations of their words and actions with the crusades. The term "crusade" itself has entered modern usage as a metaphor, as for when George W. Bush stated, in the aftermath of the 11 September attacks, about the future War on Terror: "this crusade, this war on terror, is going to take a while." It is not difficult to interpret these events as signs and precursors of modern religious intolerance, and not just against Muslims: the First Crusade, a sharp break with the past, led to a wave of anti-semitism which left behind a "trail of blood and smoldering ruins in the Jewish communities from France to Palestine".
Crusade finance and taxation left a legacy of social, financial, and legal institutions. Property became available while coinage and precious materials circulated more readily within Europe. Crusading expeditions created immense demands for food supplies, weapons, and shipping that benefited merchants and artisans. Levies for crusades contributed to the development of centralised financial administrations and the growth of papal and royal taxation. This aided development of representative bodies whose consent was required for many forms of taxation.
Originally, medieval understanding of the crusades was narrowly focussed on a limited set of interrelated texts, most notably Gesta Francorum which possibly dates from as early as 1099. The Gesta was reworked by Robert of Rheims who created a papalist, northern French template for later works. These all demonstrated a degree of martial advocacy that attributed both success and failure to God's will. This clerical view was soon challenged by vernacular adventure stories based on the work of Albert of Aachen. William of Tyre expanded on Albert's writing in his Historia. Completed by 1184, William's work describes the warrior state that Outremer had become through the tensions between divine providence and humankind. Medieval crusade historiography remained more interested in presenting moralistic lessons than information, extolling the crusades as a moral exemplar and a cultural norm.
Attitudes toward the crusades during the Reformation were shaped by confessional debates and the Ottoman expansion. The Protestant martyrologist John Foxe in his History of the Turks (1566) blamed the sins of the Catholic Church for the failure of the crusades. He also condemned the use of crusades against those he considered had maintained the faith, such as the Albigensians and Waldensians. The Lutheran scholar Matthew Dresser (1536–1607) extended this view; the crusaders were lauded for their faith but Urban II's motivation was seen as part of his conflict with Emperor Henry IV. On this view, the crusade was flawed, and the idea of restoring the physical holy places was "detestable superstition". The French Catholic lawyer Étienne Pasquier (1529–1615) was one of the first to number the crusades; he suggested there were six. His work highlights the failures of the crusades and the damage that religious conflict had inflicted on France and the church; it lists victims of papal aggression, sale of indulgences, church abuses, corruption, and conflicts at home.
Age of Enlightenment philosopher-historians such as David Hume, Voltaire and Edward Gibbon used crusading as a conceptual tool to critique religion, civilisation and cultural mores. For them the positives effects of crusading, such as the increasing liberty that municipalities were able to purchase from feudal lords, were only by-products. This view was then criticised in the 19th century by crusade enthusiasts as being unnecessarily hostile to, and ignorant of, the crusades. Alternatively, Claude Fleury and Gottfried Wilhelm Leibniz proposed that the crusades were one stage in the improvement of European civilisation; that paradigm was further developed by the Rationalists.
The idea that the crusades were an important part of national history and identity continued to evolve. In scholarly literature, the term "holy war" was replaced by the neutral German kreuzzug and French croisade. Gibbon followed Thomas Fuller in dismissing the concept that the crusades were a legitimate defence, as they were disproportionate to the threat presented; Palestine was an objective, not because of reason but because of fanaticism and superstition. William Robertson expanded on Fleury in a new, empirical, objective approach, placing crusading in a narrative of progress towards modernity. The cultural consequences of growth in trade, the rise of the Italian cities and progress are elaborated in his work. In this he influenced his student Walter Scott. Much of the popular understanding of the crusades derives from the 19th century novels of Scott and the French histories by Joseph François Michaud.
In a 2001 article—"The Historiography of the Crusades"—Giles Constable attempted to categorise what is meant by "Crusade" into four areas of contemporary crusade study. His view was that Traditionalists such as Hans Eberhard Mayer are concerned with where the crusades were aimed, Pluralists such as Jonathan Riley-Smith concentrate on how the crusades were organised, Popularists including Paul Alphandery and Etienne Delaruelle focus on the popular groundswells of religious fervour, and Generalists, such as Ernst-Dieter Hehl focus on the phenomenon of Latin holy wars. The historian Thomas F. Madden argues that modern tensions are the result of 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.
The Muslim world exhibited little interest in the crusades until the middle of the 19th century. Arabic-speaking Syrian Christians began translating French histories into Arabic, leading to the replacement of the term "wars of the Ifranj" – Franks – with al-hurub al Salabiyya – "wars of the Cross". The Ottoman Turk Namık Kemal published the first modern Saladin biography in 1872. The Jerusalem visit in 1898 of Kaiser Wilhelm prompted further interest, with the Egyptian Sayyid Ali al-Hariri producing the first Arabic history of the crusades. Modern studies can be driven by political motives, such as the hope of learning from the Muslim forces' triumph over their enemies.