Crusades

This article is about the series of medieval Christian religious wars primarily to recover the Holy Land. For the ideology and institutions associated with crusading, see Crusading movement.

For other uses, see Crusade (disambiguation) and Crusader (disambiguation).

The Crusades were a series of religious wars initiated, supported, and sometimes directed by the Latin Church in the medieval period. The best known of these Crusades are those to the Holy Land in the period between 1095 and 1291 that were intended to recover Jerusalem and its surrounding area from Islamic rule. Concurrent military activities in the Iberian Peninsula against the Moors (the Reconquista) and in northern Europe against pagan Slavic tribes (the Northern Crusades) also became known as crusades. Through the 15th century, other church-sanctioned crusades were fought against heretical Christian sects, against the Byzantine and Ottoman empires, to combat paganism and heresy, and for political reasons. Unsanctioned by the church, Popular Crusades of ordinary citizens were also frequent. Beginning with the First Crusade which resulted in the recovery of Jerusalem in 1099, dozens of Crusades were fought, providing a focal point of European history for centuries.

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 called for an armed pilgrimage to Jerusalem. Across all social strata in western Europe, there was an enthusiastic popular response. The first Crusaders had a variety of motivations, including religious salvation, satisfying feudal obligations, opportunities for renown, and economic or political advantage. Later crusades were generally conducted by more organized armies, sometimes led by a king. All were granted papal indulgences. Initial successes established four Crusader states: 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 fall of Acre in 1291. 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.

Terminology

14th-century miniature of the Second Crusade battle from the Estoire d'Eracles

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 be misleading, particularly regarding the early Crusades, and the definition remains a matter of debate among contemporary historians.

At the time of the First Crusade, iter, "journey", and peregrinatio, "pilgrimage" were used to describe 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 17th century, with the work of Louis Malmbourg. Strategic raiding was known as passagium particulare and more fundamental campaigns as passagium generale.

The terms "Franks" (Franj) 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".

Background

The period of Islamic Arab territorial expansion had been over since the 8th century. Syria and Palestine's remoteness from the focus of Islamic power struggles enabled relative peace and prosperity. Only in the Iberian Peninsula was Muslim-Western European contact more than minimal. Byzantine emperor Basil II extended the empire's territorial recovery to its furthest extent in 1025, with frontiers stretching 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 and 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. The political situation in the Middle East was changed by waves of Turkish migration—in particular, the arrival of the Seljuk Turks in the 10th century. Previously a minor ruling clan from Transoxania, they were recent converts to Islam who migrated into Iran to seek their fortune. In two decades, they conquered Iran, Iraq, and the Near East. Byzantium's attempted confrontation in 1071 to suppress the Seljuks' sporadic raiding led to the defeat at the battle of Manzikert. In the same year, Jerusalem was taken from the Fatimids by the Turkish warlord Atsiz, who seized most of Syria and Palestine as part of the expansion of the Seljuks throughout the Middle East. The Seljuk hold on the city resulting in pilgrims reported difficulties and the oppression of Christians. The result was the First Crusade.

Crusades and the Holy Land, 1095–1291

See also: Timeline of the Kingdom of Jerusalem

The Church of the Holy Sepulchre in Jerusalem

The Crusades to the Holy Land are the best known of the religious wars discussed here, beginning in 1095 and lasting some two centuries. These Crusades began with the fervent desire to liberate the Holy Land from the Muslims, and ran through eight major numbered crusades and dozens of minor crusades over two centuries.

First Crusade

Main article: First Crusade

In 1074, just three years after Manzikert and the Seljuk takeover of Jerusalem, Gregory VII began planning to launch a military campaign for the liberation of the Holy Land. Twenty years later, Urban II realized that dream, hosting the decisive Council of Piacenza and subsequent Council of Clermont in November 1095, that resulted in the mobilization of Western Europe to go to the Holy Land. Byzantine emperor Alexios I Komnenos, worried about the continued advances of the Seljuks, sent envoys to these councils asking Urban for aid against the invading Turks. Urban talked of the violence of Europe and the necessity of maintaining the Peace of God; about helping Byzantium; about the crimes being committed against Christians in the east; and about a new kind of war, an armed pilgrimage, and of rewards in heaven, where remission of sins was offered to any who might die in the undertaking. The enthusiastic crowd responded with cries of Deus lo volt! ––God wills it!

Miniature of Peter the Hermit leading the People's Crusade (Egerton 1500, Avignon, 14th century)

Immediately after Urban's proclamation, 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. They were destroyed in 1096 when the main body of Crusaders was annihilated at the battle of Civetot.

In response to Urban's call, members of the high aristocracy from Europe took the cross. Foremost amongst these was the elder statesman Raymond IV of Toulouse, who with bishop Adhemar of Le Puy commanded southern French forces. Other armies included one led by Godfrey of Bouillon and his brother Baldwin of Boulogne; forces led by Bohemond of Taranto and his nephew Tancred; and contingents under Robert Curthose, Stephen of Blois, Hugh of Vermandois, and Robert II of Flanders. The armies travelled 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, Buoyed by their success at Civetot, the over-confident Seljuks left the city unprotected, thus enabling its capture after the siege of Nicaea in May–June 1097. The first experience of Turkish tactics occurred when a force led by Bohemond and Robert was ambushed at battle of Dorylaeum in July 1097. The Normans resisted for hours before the arrival of the main army caused a Turkish withdrawal.

The Crusader army marched to the former Byzantine city of Antioch that had been in Muslim control since 1084. The Crusaders began the siege of Antioch in October 1097 and fought for eight months to a stalemate. Finally, Bohemond persuaded a guard in the city to open a gate. The Crusaders entered, massacring the Muslim inhabitants as well as many Christians. A force to recapture the city was raised by Mosul. The discovery of the Holy Lance by mystic Peter Bartholomew may have boosted the morale of the Crusaders. The Byzantines did not march to the assistance of the Crusaders. Instead Alexius retreated from Philomelium. The Greeks were never truly forgiven for this perceived betrayal. 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, the Muslims retreated and abandoned the siege.

Proceeding down the Mediterranean coast, the Crusaders encountered little resistance, as local rulers preferred to make peace with them and furnish them with supplies rather than fight. The next significant combat was the siege of Arqa begun on 14 February 1099. Since the death of Adhemar after Antioch, there had been no spiritual leader of the crusade, and ever since the discovery of the Holy Lance, there had been accusations of fraud among the clerical factions. On 8 April 1099, Arnulf of Chocques, chaplain to Robert Curthose, challenged Bartholomew to an ordeal by fire. Peter underwent the ordeal and died after days of agony from his wounds, which discredited the Holy Lance as a fake. The siege of Arqa lasted until 13 May, when the Crusaders left having captured nothing, moving onward towards Jerusalem.

News arrived that the Fatimids had taken Jerusalem from the Seljuks, making it imperative to attack. 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. On 7 June 1099, the Crusaders reached Jerusalem. Many Crusaders wept upon seeing the city they had journeyed so long to reach. An initial attack on the city failed, and the siege of Jerusalem of 1099 became a stalemate, until they breached the walls on 15 July 1099. Iftikhar al-Dawla, the commander of the garrison, struck a deal with Raymond, surrendering the citadel in return for being granted safe passage to Ascalon. For two days the Crusaders massacred the inhabitants and pillaged the city. Jerusalem had been returned to Christian rule. Urban II died on 29 July 1099, fourteen days after the fall of Jerusalem to the Crusaders, but before news of the event had reached Italy. He was succeeded by Paschal II.

On July 22, 1099, a council was held in the Church of the Holy Sepulchre and Godfrey of Bouillon took the leadership, not called king but rather with the title Advocatus Sancti Sepulchri (Defender of the Holy Sepulchre). At this point, most Crusaders considered their pilgrimage complete and returned to Europe. Godfrey was left with a small force––a mere 300 knights and 2,000 infantry––to defend the kingdom. The Frankish position was enhanced by defeating an Egyptian relief force at the battle of Ascalon in August 1099. The First Crusade thus ended successfully and resulted in the creation of the Kingdom of Jerusalem.

The Crusader States in 1135

The Kingdom of Jerusalem, 1099–1147

Main article: Crusader states

Godfrey of Bouillon died on 18 July 1100, likely from typhoid. The news of his death was met with mourning in Jerusalem, laying for five days in state before his burial at the Church of the Holy Sepulchre. The Jerusalem knights offered the kingdom to Godfrey's brother Baldwin I of Jerusalem, then Count of Edessa. Godfrey's last battle, the siege of Arsuf, would be completed by Baldwin in April 1101. Meanwhile, Dagobert of Pisa, now Latin Patriarch of Jerusalem, made the same offer to Bohemond, and asking that he prevent Baldwin's expected travel to Jerusalem. But the letter was intercepted and Bohemond was captured with Richard of Salerno by the Danishmends after the battle of Melitene in August 1100. Baldwin I was crowned as the first king of Jerusalem on Christmas Day 1100 by Dagobert at the Church of the Nativity. Baldwin's cousin Baldwin of Bourcq, later his successor as Baldwin II, was named Count of Edessa, and Tancred became regent of Antioch during Bohemond's captivity, lasting through 1103.

The Crusade of 1101 was initiated by Paschal II when he learned of the precarious position of the remaining forces in the Holy Land. The host consisted of four separate armies, sometimes regarded as a second wave following the First Crusade. The first army was Lombardy, led by Anselm, archbishop of Milan. They were joined by a force led by Conrad, constable to the German emperor, Henry IV. A second army, the Nivernois, was commanded by William II of Nevers. The third group from northern France was led by Stephen of Blois and Stephen of Burgundy. They were joined by Raymond of Saint-Gilles, now in the service of the emperor. The fourth army was led by William IX of Aquitaine and Welf IV of Bavaria. The Crusaders faced their old enemy Kilij Arslan and his Seljuk forces first met the Lombard and French contingents in August 1101 at the battle of Mersivan, with the crusader camp captured. The Nivernois contingent was decimated that same month at Heraclea, with nearly the entire force wiped out, except for the count William and a few of his men. The Aquitainians and Bavarians reached Heraclea in September where again the Crusaders were massacred. The Crusade of 1101 was a total disaster both militarily and politically, showing the Muslims that the Crusaders were not invincible.

The reign of Baldwin I began in 1100 and oversaw the consolidation of the kingdom in the face of enemies to the north, the Seljuks, and the Fatimids to the south. Al-Afdal Shahanshah, the powerful Fatimid vizier, anxious to recover the lands lost to the Franks, initiated the First battle of Ramla on 7 September 1101 in which his forces were narrowly defeated, by those of Baldwin I. On 17 May 1102, the Crusaders were not so lucky, suffering a major defeat at the hands of the Fatimids, under the command of al-Afdal's son Sharaf al-Ma’ali at the Second battle of Ramla. Among the slain were veterans of the Crusade of 1101, Stephen of Blois and Stephen of Burgundy. Conrad of Germany fought so valiantly that his attackers offered to spare his life if he surrendered. The kingdom was on the verge of collapse after the defeat, recovering after the successful battle of Jaffaon 27 May. Al-Afdal tried once more in the Third battle of Ramla in August 1105 and, defeated, the Fatimid threat to the kingdom subsided for two decades.

Second Crusade

Main article: Second Crusade

The first of the Crusader states––Edessa––was also the first to fall after the first siege of Edessa, arriving on 28 November 1144. Calls for a Second Crusade were immediate, and was the first led by European kings. The disastrous performance of this campaign in the Holy Land damaged the standing of the papacy, soured relations between the Christians of the kingdom and the West for many years, and encouraged the Muslims of Syria to even greater efforts to defeat the Franks. The dismal failures of this Crusade then set the stage for the fall of Jerusalem, leading to the Third Crusade. Concurrent campaigns as part of the Reconquista and Northern Crusades are also sometimes associated with this Crusade

Eugene III, recently elected pope, issued the bull Quantum praedecessores on 1 December 1145, the first such papal bull issued calling for a new crusade, meant to be more organized and centrally controlled than the First. The armies would be led by the strongest kings of Europe and a route that would be pre-planned. The French contingent departed in June 1147. The French met the remnants of Conrad's army in northern Turkey, and Conrad joined Louis' force. They fended off a Seljuk attack at the battle of Ephesus on 24 December 1147. A few days later, they were again victorious at the battle of the Meander, late in 1147. Louis was not as lucky at the battle of Mount Cadmus on 6 January 1148, where the Seljuk army inflicted heavy losses on the Crusaders. The army sailed for Antioch in January, almost totally destroyed by battle and sickness.

The Crusader army arrived at Antioch on 19 March 1148 with the intent on moving to retake Edessa, but the objective was changed to Damascus. Bad luck and poor tactics led to the disastrous five-day siege of Damascus from 24 to 28 July 1148. The barons of Jerusalem withdrew support and the Crusaders retreated before the arrival of a relief army of the Muslims. The French and German forces felt betrayed by the other, lingering for a generation due to the defeat, to the ruin of the Christian kingdoms in the Holy Land.

In the spring of 1147, Eugene authorized the expansion of his mission into the Iberian peninsula, equating these campaigns against the Moors with the rest of the Second Crusade. The successful siege of Lisbon, from 1 July to 25 October 1147, was followed by the six-month siege of Tortosa, ending on 30 December 1148 with a defeat for the Moors. In the north, some Germans were reluctant to fight in the Holy Land while the pagan Wends were a more immediate problem. The resulting Wendish Crusade of 1147 was partially successful but failed to convert the pagans to Christianity.

The Near East, c. 1190, at the inception of the Third Crusade

Third Crusade

Main article: Third Crusade

The years following the founding of the Kingdom of Jerusalem were met with multiple disasters. The Second Crusade did not achieve its goals, and left the Muslim East in a stronger position with the rise of Saladin. A united Egypt–Syria led to the loss of Jerusalem itself, and Western Europe had no choice but to launch the Third Crusade, this time led by the kings of Europe.

The news of the disastrous defeat at the battle of Hattin and subsequent fall of Jerusalem gradually reached Western Europe. Urban III died shortly after hearing the news, and his successor Gregory VIII issued the bull Audita tremendi on 29 October 1187 describing the events in the East and urging all Christians to take up arms and go to the aid of those in the Kingdom of Jerusalem, calling for a new crusade to the Holy Land––the Third Crusade––to be led by Frederick Barbarossa and Richard I of England.

Richard the Lionheart on his way to Jerusalem, James William Glass (1850)

Frederick took the cross in March 1188. Frederick sent an ultimatum to Saladin, demanding the return of Palestine and challenging him to battle and in May 1189, Frederick's host departed for Byzantium. In March 1190, Frederick embarked to Asia Minor. The armies coming from western Europe pushed on through Anatolia, defeating the Turks and reaching as far as Cilician Armenia. On 10 June 1190, Frederick drowned near Silifke Castle. His death caused several thousand German soldiers to leave the force and return home. The remaining German army moved under the command of the English and French forces that arrived shortly thereafter.

Richard the Lionheart had already taken the cross as the Count of Poitou in 1187. His father Henry II of England and Philip II of France had done so on 21 January 1188 after receiving news of the fall of Jerusalem to Saladin. After Richard became king, he and Philip agreed to go on the Third Crusade, since each feared that during his absence the other might usurp his territories.

Richard I and Philip II of France agreed to go on the Crusade in January 1188. Arriving in the Holy Land, Richard led his support to the stalemated siege of Acre. The Muslim defenders surrendered on 12 July 1191. Richard remained in sole command of the Crusader force after the departure of Philip II on 31 July 1191. On 20 August 1191, Richard had the more than 2000 prisoners beheaded at the so-called massacre of Ayyadieh. Saladin subsequently ordered the execution of his Christian prisoners in retaliation.

Richard moved south, defeating Saladin's forces at the battle of Arsuf on 7 September 1191. Three days later, Richard took Jaffa, held by Saladin since 1187, and advanced inland towards Jerusalem. On 12 December 1191 Saladin disbanded the greater part of his army. Learning this, Richard pushed his army forward, to within 12 miles from Jerusalem before retreating back to the coast. The Crusaders made another advance on Jerusalem, coming within sight of the city in June before being forced to retreat again. Hugh III of Burgundy, leader of the Franks, was adamant that a direct attack on Jerusalem should be made. This split the Crusader army into two factions, and neither was strong enough to achieve its objective. Without a united command the army had little choice but to retreat back to the coast.

On 27 July 1192, Saladin's army began the battle of Jaffa, capturing the city. Richard's forces stormed Jaffa from the sea and the Muslims were driven from the city. Attempts to retake Jaffa failed and Saladin was forced to retreat. On 2 September 1192 Richard and Saladin entered into the Treaty of Jaffa, providing that Jerusalem would remain under Muslim control, while allowing unarmed Christian pilgrims and traders to freely visit the city. This treaty ended the Third Crusade.

Three years later, Henry VI launched the Crusade of 1197. While his forces were en route to the Holy Land, Henry VI died in Messina on 28 September 1197. The nobles that remained captured the Levant coast between Tyre and Tripoli before returning to Germany. The Crusade ended on 1 July 1198 after capturing Sidon and Beirut.

Fourth Crusade

Main articles: Fourth Crusade and Sack of Constantinople

Conquest of the Orthodox city of Constantinople by the Crusaders in 1204 (BNF Arsenal MS 5090, 15th century)

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.

Fifth Crusade

Main article: Fifth Crusade

The Fifth Crusade (1217–1221) was a campaign by Western Europeans to reacquire Jerusalem and the rest of the Holy Land by first conquering Egypt, ruled by the sultan al-Adil, brother of Saladin. In 1213, Innocent III called for another Crusade at the Fourth Lateran Council, and in the papal bull Quia maior. Innocent died in 1216 and was succeeded by Honorius III who immediately called on Andrew II of Hungary and Frederick II of Germany to lead a Crusade. Frederick had taken the cross in 1215, but hung back, with his crown still in contention, and Honorius delayed the expedition.

Crusaders attack the tower of during the siege of Damietta in a painting by Cornelis Claesz van Wieringen

Andrew II left for Acre in August 1217, joining John of Brienne, king of Jerusalem. The initial plan of a two-prong attack in Syria and in Egypt was abandoned and instead the objective became limited operations in Syria. After accomplishing little, the ailing Andrew returned return to Hungary early in 1218. As it became clear that Frederick II was not coming to east, the remaining commanders began the planning to attack the Egyptian port of Damietta.

The fortifications of Damietta were impressive, and included the Burj al-Silsilah––the chain tower––with massive chains that could stretch across the Nile. The Siege of Damietta began in June 1218 with a successful assault on the tower. The loss of the tower was a great shock to the Ayyubids, and the sultan al-Adil died soon thereafter. He was succeeded as sultan by his son al-Kamil. Further offensive action by the Crusaders would have to wait until the arrival of additional forces, including legate Pelagius with a contingent of Romans. A group from England arrived shortly thereafter.

By February 1219, the Crusaders now had Damietta surrounded, and al-Kamil opened negotiations with the Crusaders, asking for envoys to come to his camp. He offered to surrender the kingdom of Jerusalem, less the fortresses of al-Karak and Krak de Montréal, guarding the road to Egypt, in exchange for the evacuation of Egypt. John of Brienne and the other secular leaders were in favor of the offer, as the original objective of the Crusade was the recovery of Jerusalem. But Pelagius and the leaders of the Templars and Hospitallers refused. Later, Francis of Assisi arrived to negotiate unsuccessfully with the sultan.

In November 1219, the Crusaders entered Damietta and found it abandoned, al-Kamil having moved his army south. In the captured city, Pelagius was unable to prod the Crusaders from their inactivity, and many returned home, their vow fulfilled. Al-Kamil took advantage of this lull to reinforce his new camp at Mansurah, renewing his peace offering to the Crusaders, which was again refused. Frederick II sent troops and word that he would soon follow, but they wereunder orders not to begin offensive operations until he had arrived.

In July 1221, Pelagius began to advance to the south. John of Brienne argued against the move, but was powerless to stop it. Already deemed a traitor for opposing the plans and threatened with excommunication, John joined the force under the command of the legate. In the ensuing Battle of Mansurah in late August, al-Kamil had the sluices along the right bank of the Nile opened, flooding the area and rendering battle impossible. Pelagius had no choice but to surrender.

The Crusaders still had some leverage as Damietta was well-garrisoned. They offered the sultan a withdrawal from Damietta and an eight-year truce in exchange for allowing the Crusader army to pass, the release of all prisoners, and the return of the relic of the True Cross. Prior to the formal surrender of Damietta, the two sides would maintain hostages, among them John of Brienne and Hermann of Salza for the Franks side and a son of al-Kamil for Egypt. The masters of the military orders were dispatched to Damietta, where the forces were resistant to giving up, with the news of the surrender, which happened on 8 September 1221. The Fifth Crusade was over, a dismal failure, unable to even gain the return of the piece of the True Cross.

Sixth Crusade

Main article: Sixth Crusade

Holy Roman Emperor Frederick II (left) meets al-Kamil (right), illumination from Giovanni Villani's Nuova Cronica (Vatican Library ms. Chigiano L VIII 296, 14th century).

The Sixth Crusade (1228–1229) was a military expedition to recapture the city of Jerusalem. It began seven years after the failure of the Fifth Crusade and involved very little actual fighting. The diplomatic maneuvering of Frederick II resulted in the Kingdom of Jerusalem regaining some control over Jerusalem for much of the ensuing fifteen years. The Sixth Crusade is also known as the Crusade of Frederick II.

Of all the European sovereigns, only Frederick II, the Holy Roman Emperor, was in a position to regain Jerusalem. Frederick was, like many of the 13th-century rulers, a serial crucesignatus, having taken the cross multiple times since 1215. After much wrangling, an onerous agreement between the emperor and pope Honorius III was signed on 25 July 1225 at San Germano. Frederick promised to depart on the Crusade by August 1227 and remain for two years. During this period, he was to maintain and support forces in Syria and deposit escrow funds at Rome in gold. These funds would be returned to the emperor once he arrived at Acre. If he did not arrive, the money would be employed for the needs of the Holy Land. Frederick II would go on the Crusade as king of Jerusalem. He married John of Brienne's daughter Isabella II by proxy in August 1225 and they were formally married on 9 November 1227. Frederick claimed the kingship of Jerusalem despite John having beengiven assurances that he would remain as king. Frederick took the crown in December 1225. Frederick's first royal decree was to grant new privileges on the Teutonic Knights, placing them on equal footing as the Templars and Hospitallers.

After the Fifth Crusade, the Ayyubid sultan al-Kamil became involved in civil war in Syria and, having unsuccessfully tried negotiations with the West beginning in 1219, again tried this approach, offering return of much of the Holy Land in exchange for military support. Becoming pope in 1227, Gregory IX was determined to proceed with the Crusade. The first contingents of Crusaders then sailed in August 1227, joining with forces of the kingdom and fortifying the coastal towns. The emperor was delayed while his ships were refitted. He sailed on 8 September 1227, but before they reached their first stop, Frederick was struck with the plague and disembarked to secure medical attention. Resolved to keep his oath, he sent his fleet on to Acre. He sent his emissaries to inform Gregory IX of the situation, but the pope did not care about Frederick's illness, just that he had not lived up to his agreement. Frederick was excommunicated on 29 September 1227, branded a wanton violator of his sacred oath taken many times..

Frederick made his last effort to be reconciled with Gregory. It had no effect and Frederick sailed from Brindisi in June 1228. After a stop at Cyprus, Frederick II arrived in Acre on 7 September 1228 and was received warmly by the military orders, despite his excommunication. Frederick's army was not large, mostly German, Sicilian and English. Of the troops he had sent in 1227 had mostly returned home. He could neither afford nor mount a lengthening campaign in the Holy Land. The Sixth Crusade would be one of negotiation.

After resolving the internecine struggles in Syria, al-Kamil's position was stronger than it was a year before when he made his original offer to Frederick. For unknown reasons, the two sides came to an agreement. The resultant Treaty of Jaffa was concluded on 18 February 1229, with al-Kamil surrendering Jerusalem, with the exception of some Muslim holy sites, and agreeing to a ten-year truce. Frederick entered Jerusalem on 17 March 1229 and received the formal surrender of the city by al-Kamil's agent and the next day, crowned himself. On 1 May 1229, Frederick departed from Acre and arrived in Sicily a month before the pope knew that he had left the Holy Land. Frederick obtained from the pope relief from his excommunication on 28 August 1230 at the Treaty of Ceprano.

The results of the Sixth Crusade were not universally acclaimed. Two letters from the Christian side tell differing stories, with Frederick touting the great success of the endeavor and the Latin patriarch painting a darker picture of the emperor and his accomplishments. On the Muslim side, al-Kamil himself was pleased with the accord, but other regarded the treaty as a disastrous event. In the end, the Sixth Crusade successfully returned Jerusalem to Christian rule and had set a precedent, in having achieved success on crusade without papal involvement.

The Crusades of 1239–1241

Main article: Barons' Crusade

The Crusades of 1239–1241, also known as the Barons' Crusade, were a series of crusades to the Holy Land that, in territorial terms, were the most successful since the First Crusade. The major expeditions were led separately by Theobald I of Navarre and Richard of Cornwall. These crusades are sometimes discussed along with that of Baldwin of Courtenay to Constantinople.

The defeat of the Crusaders at Gaza, depicted in the Chronica majora of Matthew Paris, 13th century.

In 1229, Frederick II and the Ayyubid sultan al-Kamil, had agreed to a ten-year truce. Nevertheless, Gregory IX, who had condemned this truce from the beginning, issued the papal bull Rachel suum videns in 1234 calling for a new crusade once the truce expired. A number of English and French nobles took the cross, but the crusade’s departure was delayed because Frederick, whose lands the crusaders had planned to cross, opposed any crusading activity before the expiration of this truce. Frederick was again excommunicated in 1239, causing most crusaders to avoid his territories on their way to the Holy Land.

The French expedition was led by Theobald I of Navarre and Hugh of Burgundy, joined by Amaury of Montfort and Peter of Dreux. On 1 September 1239, Theobald arrived in Acre, and was soon drawn into the Ayyubid civil war, which had been raging since the death of al-Kamil in 1238. At the end of September, al-Kamil’s brother as-Salih Ismail seized Damascus from his nephew, as-Salih Ayyub, and recognized al-Adil II as sultan of Egypt. Theobald decided to fortify Ascalon to protect the southern border of the kingdom and to move against Damascus later. While the Crusaders were marching from Acre to Jaffa, Egyptian troops moved to secure the border in what became the Battle at Gaza. Contrary to Theobald’s instructions and the advice of the military orders, a group decided to move against the enemy without further delay, but they were surprised by the Muslims who inflicted a devasting defeat on the Franks. The masters of the military orders then convinced Theobald to retreat to Acre rather than pursue the Egyptians and their Frankish prisoners. A month after the battle at Gaza, an-Nasir Dā’ūd, emir of Kerak, seized Jerusalem, virtually unguarded. The internal strife among the Ayyubids allowed Theobald to negotiate the return of Jerusalem. In September 1240, Theobald departed for Europe, while Hugh of Burgundy remained to help fortify Ascalon.

On 8 October 1240, the English expedition arrived, led by Richard of Cornwall. The force marched to Jaffa, where they completed the negotiations for a truce with Ayyubid leaders begun by Theobald just a few months prior. Richard consented, the new agreement was ratified by Ayyub by 8 February 1241, and prisoners from both sides were released on 13 April. Meanwhile, Richard’s forces helped to work on Ascalon’s fortifications, which were completed by mid-March 1241. Richard entrusted the new fortress to an imperial representative, and departed for England on 3 May 1241.

In July 1239, Baldwin of Courtenay, the young heir to the Latin Empire, travelled to Constantinople with a small army. In the winter of 1239, Baldwin finally returned to Constantinople, where he was crowned emperor around Easter of 1240, after which he launched his crusade. Baldwin then besieged and captured Tzurulum, a Nicaean stronghold seventy-five miles west of Constantinople.

Although the Barons' Crusade returned the kingdom to its largest size since 1187, the gains would be dramatically reversed a few years later. On 15 July 1244, the city was reduced to ruins during the Siege of Jerusalem of 1244 and its Christians massacred by the Khwarazmians. A few months later, the Battle of La Forbie permanently crippled Christian military power in the Holy Land. The sack of the city and the massacre which accompanied it encouraged Louis IX of France to organize the Seventh Crusade.

Crusades of Saint Louis

Main articles: Seventh Crusade, Eighth Crusade, and Ninth Crusade

Thirteenth century politics in the eastern Mediterranean were complex was dominated by the French, led by the devout Louis IX, king of France, and his ambitiously expansionist brother Charles. 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 threat presented by an invasion by the Mongols led to one of the competing Mamluk leaders, 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 and Baibers assumed control.

Between 1265 and 1271, 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. Dissension 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 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 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.

Decline and fall of the Crusader States

Miniature of the Siege of Acre (1291) (Estoire d'Oultre-Mer, BNF fr. 2825, fol 361v, ca. 1300)

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.

Other crusades

Map of the branches of the Teutonic Order in Europe around 1300. Shaded area is sovereign territory.

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 Spanish 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.

Urban II equated the crusades for Jerusalem with the ongoing Catholic invasion of the Iberian Peninsula and crusades were preached in 1114 and 1118, but it was Pope Callixtus II who proposed dual fronts in Spain and the Middle East in 1122. By the time of the Second Crusade the three Spanish 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 fighters responding to the preaching of Innocent III. Many of these deserted because of the Spanish tolerance of the defeated Muslims, for whom the Reconquista was a war of domination rather than extermination. In contrast the Christians formerly living under Muslim rule called Mozarabs had the Roman Rite relentlessly imposed on them and were absorbed into mainstream Catholicism. Al-Andalus, Islamic Spain, was completely suppressed in 1492 when the Emirate of Granada surrendered.

In 1147, Pope Eugene III extended Calixtus's idea by authorising a crusade on the German north-eastern frontier against the pagan Wends from what was primarily economic conflict. From the early 13th century, there was significant involvement of military orders, such as the Livonian Brothers of the Sword and the Order of Dobrzyń. The Teutonic Knights diverted efforts from the Holy Land, absorbed these orders and established the State of the Teutonic Order. This evolved the Duchy of Prussia and Duchy of Courland and Semigallia in 1525 and 1562, respectively.

Miniatures showing Pope Innocent III excommunicating, and the crusaders massacring, Cathars (BL Royal 16 G VI, fol. 374v, 14th century)

By the beginning of the 13th century Papal reticence in applying crusades against the papacy's political opponents and those considered heretics. Innocent III proclaimed a crusade against Catharism that failed to suppress the heresy itself but ruined the culture the Languedoc. This set a precedent that was followed in 1212 with pressure exerted on the city of Milan for tolerating Catharism, in 1234 against the Stedinger peasants of north-western Germany, in 1234 and 1241 Hungarian crusades against Bosnian heretics. The historian Norman Housley notes the connection between heterodoxy and anti-papalism in Italy. Indulgence was offered to anti-heretical groups such as the Militia of Jesus Christ and the Order of the Blessed Virgin Mary. Innocent III declared the first political crusade against Frederick II's regent, Markward von Annweiler, and when Frederick later threatened 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. However, 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.

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.

The threat of the expanding Ottoman Empire prompted further campaigns. In 1389, the Ottomans defeated the Serbs at the Kosovo, won control of the Balkans from the Danube to the Gulf of Corinth, in 1396 defeated French crusaders and King Sigismund of Hungary at the Nicopolis, in 1444 destroyed a crusading Polish and Hungarian force at Varna, four years later again defeated the Hungarians at Kosovo and in 1453 captured Constantinople. The 16th century saw growing rapprochement. The Habsburgs, French, Spanish and Venetians and Ottomans all signed treaties. Francis I of France allied with all quarters, including from German Protestant princes and Sultan Suleiman the Magnificent. 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. Crusading became a financial exercise; precedence was given to the commercial and political objectives. The military threat presented by the Ottoman Turks diminished, making anti-Ottoman crusading obsolete in 1699 with the final Holy League.

Historiography

Further information: Historians and histories of the Crusades

The historiography of the Crusades is concerned with their "history of the histories" during the Crusader period. The subject is a complex one, with overviews provided in Select Bibliography of the Crusades, Modern Historiography, and Crusades (Bibliography and Sources). The histories describing the Crusades are broadly of three types: (1) The primary sources of the Crusades, which include works written in the medieval period, generally by participants in the Crusade or written contemporaneously with the event, letters and documents in archives, and archaeological studies; (2) secondary sources, beginning with early consolidated works in the 16th century and continuing to modern times; and (3) tertiary sources, primarily encyclopedias, bibliographies and genealogies.

William of Tyre writing his history, from a 13th-century Old French translation, Bibliothèque Nationale, Paris, MS 2631, f.1r

Primary sources. The primary sources for the Crusades are generally presented in the individual articles on each Crusade and summarized in the list of sources for the Crusades. For the First Crusade, the original Latin chronicles, including the Gesta Francorum, works by Albert of Aachen and Fulcher of Chartres, The Alexiad by Byzantine princess Anna Komnene, the Complete Work of History by Muslim historian Ali ibn al-Athir, and the Chronicle of Armenian historian Matthew of Edessa, provide for a starting point for the study of the Crusades' historiography. Many of these and related texts are found in the collections Recueil des historiens des croisades (RHC) and Crusade Texts in Translation. The work of William of Tyre, Historia Rerum in Partibus Transmarinis Gestarum, and its continuations by later historians complete the foundational work of the traditional Crusade. Some of these works also provide insight into the later Crusades and Crusader states. Other works of note include:

• Eyewitness accounts of the Second Crusade by Odo of Deuil and Otto of Freising. The Arab view from Damascus is provided by ibn al-Qalanisi.
• Works on the Third Crusade such as Libellus de Expugnatione Terrae Sanctae per Saladinum expeditione, the Itinerarium Regis Ricardi, and the works of Crusaders Tageno and Roger of Howden, and the narratives of Richard of Devizes, Ralph de Diceto, Ralph of Coggeshall and Arnold of Lübeck. The Arabic works by al-Isfahani and al-Maqdisi as well as the biography of Saladin by Baha ad-Din ibn Shaddad are also of interest.
• The Fourth Crusade is described in the Devastatio Constantinopolitana and works of Geoffrey of Villehardouin, in his chronicle De la Conquête de Constantinople, Robert de Clari and Gunther of Pairis. The view of Byzantium is provided by Niketas Choniates and the Arab perspective is given by Abū Shāma and Abu’l-Fida.
• The history of the Fifth and Sixth Crusades is well represented in the works of Jacques de Vitry, Oliver of Paderborn and Roger of Wendover, and the Arabic works of Badr al-Din al-Ayni.
• Key sources for the later Crusades include Gestes des Chiprois, Jean de Joinville's Life of Saint Louis, as well as works by Guillaume de Nangis, Matthew Paris, Fidentius of Padua and al-Makrizi.

After the fall of Acre, the crusades continued in through the 16th century. Principal references on this subject are the Wisconsin Collaborative History of the Crusades and Norman Housley's The Later Crusades, 1274-1580: From Lyons to Alcazar. Complete bibliographies are also given in these works.

Secondary sources. The secondary sources of the Crusades began in the 16th century, with the first use of the term crusades was by 17th century French historian Louis Maimbourg in his Histoire des Croisades pour la délivrance de la Terre Sainte. Notable works of the 18th century include Voltaire's Histoire des Croisades, and Edward Gibbon's Decline and Fall of the Roman Empire, excerpted as The Crusades, A.D. 1095–1261. This edition also includes an essay on chivalry by Sir Walter Scott, whose works helped popularize the Crusades. Early in the 19th century, the monumental Histoire des Croisades was published by the French historian Joseph François Michaud, a major new narrative based on original sources

These histories have provided evolving views of the Crusades as discussed in detail in the Historiography writeup in Crusading movement. Modern works that serve as secondary source material are listed in the Bibliography section below and need no further discussion here.

Tertiary sources. Three works stand out as excellent references. These are: Louis Bréhier's multiple works on the Crusades in the Catholic Encyclopedia; the works of Ernest Barker in the Encyclopædia Britannica (11th edition), later expanded into a separate publication; and The Crusades—An Encyclopedia (2006), edited by historian Alan V. Murray.

Bibliography

• Abulafia, David (1992). Frederick II: A Medieval Emperor. Oxford University Press. ISBN 019508040-8.
• Asbridge, Thomas (2004). The First Crusade: A New History. Oxford. ISBN 0-19-517823-8.
• Asbridge, Thomas (2012). The Crusades: The War for the Holy Land. Simon & Schuster. ISBN 978-1-84983-688-3.
• Barker, Ernest (1923). The Crusades. Oxford University Press, London.
• Christie, Niall (2014). Muslims and Crusaders: Christianity’s Wars in the Middle East, 1095-1382, from the Islamic Sources. Routledge. ISBN 978-1138543102.
• Gibb, H. A. R. (1969). The Aiyūbids (PDF). A History of the Crusades (Setton), Volume II.
• Housley, Norman (1982). The Italian Crusades: The Papal-Angevin Alliance and the Crusades Against Christian Lay Powers, 1254-1343. Oxford University Press. ISBN 978-0198219255.
• Housley, Norman (1992). The Later Crusades, 1274-1580: From Lyons to Alcazar. Oxford University Press. ISBN 978-0198221364.
• Housley, Norman (1995). "The Crusading Movement 1271-1700". In Riley-Smith, Jonathan (ed.). The Oxford Illustrated History of The Crusades. Oxford University Press. pp. 260–294. ISBN 978-0-19285428-5.
• Jotischky, Andrew (2004). Crusading and the Crusader States (1st ed.). Pearson Longman. ISBN 978-0-582-41851-6.
• Lewis, Kevin James (2017). The Counts of Tripoli and Lebanon in the Twelfth Century: Sons of Saint-Gilles. Routledge. ISBN 978-1-4724-5890-2.
• Lock, Peter (2006). The Routledge Companion to the Crusades. Routledge. doi:10.4324/9780203389638. ISBN 0-415-39312-4.
• Maalouf, Amin (2006). The Crusades through Arab Eyes. Saqi Books. ISBN 9780863560231.
• Madden, Thomas F. (2013). The Concise History of the Crusades. Rowman & Littlefield. ISBN 978-1-442-21576-4.
• Munro, Dana Carleton (1902). Letters of the Crusaders. University of Pennsylvania.
• Murray, Alan V. (2006). The Crusades—An Encyclopedia. ABC-CLIO. ISBN 978-1-57607-862-4.
• Norgate, Kate (1924). Richard the Lion Heart. Macmillan and Co.
• Oman, Charles (1924). A History of the Art of War in the Middle Ages. Metheun.
• Perry, Guy (2013). John of Brienne: King of Jerusalem, Emperor of Constantinople, c. 1175–1237. Cambridge University Press. ISBN 9781107043107.
• Phillips, Jonathan (2009). Holy Warriors: A Modern History of the Crusades. Random House. ISBN 9780224079372.
• Prawer, Joshua (1972). The Crusaders' Kingdom. Phoenix Press. ISBN 978-1-84212-224-2.
• Richard, Jean C. (1999). The Crusades, c.1071 – c.1291. Cambridge University Press. ISBN 978-0-521-62566-1.
• Riley-Smith, Jonathan (1995). "The Crusading Movement and Historians". In Riley-Smith, Jonathan (ed.). The Oxford Illustrated History of The Crusades. Oxford University Press. pp. 1–12. ISBN 978-0-19285428-5.
• Riley-Smith, Jonathan (1995b). "The Crusading Movement 1096-1274". In Riley-Smith, Jonathan (ed.). The Oxford Illustrated History of The Crusades. Oxford University Press. pp. 34–66. ISBN 978-0-19285428-5.
• Robson, William (1855). The Great Sieges of History. Routledge.
• Runciman, Steven (1951). A History of the Crusades, Volume One: The First Crusade and the Foundation of the Kingdom of Jerusalem. Cambridge University Press. ISBN 9780521347709.
• Runciman, Steven (1952). A History of the Crusades, Volume Two: The Kingdom of Jerusalem and the Frankish East, 1100-1187. Cambridge University Press. ISBN 9780521347716.
• Runciman, Steven (1954). A History of the Crusades, Volume Three: The Kingdom of Acre and the Later Crusades. Cambridge University Press. ISBN 9780521347723.
• Setton, Kenneth M. (1969). A History of the Crusades. University of Wisconsin Press.
• Tyerman, Christopher (1996). England and the Crusades, 1095-1588. University of Chicago Press. ISBN 0-226-82012-2.
• Tyerman, Christopher (2006). God's War: A New History of the Crusades. Belknap Press. ISBN 978-0-674-02387-1.
• Tyerman, Christopher (2009). The Crusades: A Brief Insight. Sterling Press. ISBN 978-0192806550.
• Tyerman, Christopher (2011). The Debate on the Crusades, 1099–2010. Manchester University Press. ISBN 978-0-7190-7320-5.
• Tyerman, Christopher (2019). The World of the Crusades. Yale University Press. ISBN 978-0-300-21739-1.
• von Sybel, Heinrich (1861). The History and Literature of the Crusades. G. Routledge & Son, Limited.
• Wolff, Robert Lee (1969). The Latin Empire of Constantinople, 1204-1312 (PDF). A History of the Crusades (Setton), Volume II.

See also

• Crusader states
• Crusading movement
• History of Christianity
• List of Crusades to Europe and the Holy Land
• Military history of the Crusader states
• Women in the Crusades