Crusading: A Religious and Military Movement from the Middle Ages to the Early Modern Era

Crusading was a Latin Christian movement that joined armed campaigns to religious vows and promises of spiritual reward. It began with Pope Urban II’s call at Clermont in 1095 and first focused on aid to eastern Christians and control of Jerusalem and other holy places. Over time, campaigns associated with the movement took place not only in the eastern Mediterranean but also in Iberia, the Baltic and within Europe. The Levantine states created by the First Crusade endured for different lengths of time, but crusading continued after Latin rule on the mainland ended in 1291. Its forms and targets changed through later medieval and early modern campaigns, while its meaning was repeatedly reshaped by later generations.

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How the crusading movement changed

The First Crusade emerged from the overlap of armed pilgrimage, Christian ideas about penitence and warfare, and growing papal authority. In March 1095, Byzantine emperor Alexios I Komnenos sought military assistance from Urban II. At Clermont that November, Urban called for an expedition. Participants took a vow and wore a cross on their clothing, making their commitment visible. The movement was not a single, continuous war: expeditions differed in leadership, destination, size and result, and participants did not all share the same aims.

The First Crusade captured Jerusalem in 1099 and led to the creation of Latin-ruled states in the Levant. Their defence prompted further expeditions. The fall of the city of Edessa to Zengi in 1144 helped bring about the Second Crusade, whose attack on Damascus failed in 1148. In 1187, Saladin defeated the Jerusalemite army at Hattin and took Jerusalem. The Third Crusade restored Frankish control of parts of the coast, but not the city. In 1204, the Fourth Crusade, originally directed against Egypt, was diverted to Constantinople. Its capture and sack by western crusaders inflicted deep damage on relations with the Byzantine Empire, another Christian power.

Later expeditions continued to target the eastern Mediterranean. The Fifth Crusade attacked Egypt and ended in failure in 1221. During the Sixth Crusade, Emperor Frederick II negotiated the return of Jerusalem and other places to Christian control in 1229, but the agreement was temporary; Jerusalem was sacked in 1244. Mamluk forces, ruling Egypt and Syria, gradually conquered the remaining Latin-held territories. Acre fell in 1291, ending Latin rule on the Levantine mainland.

Meanwhile, the idea of a crusade had spread to other regions and causes. In Iberia, it became attached to conflicts between Christian kingdoms and Muslim rulers, which had their own local histories and political aims. In 1147, papal approval extended crusading privileges to a campaign against the pagan Wends in the Baltic. The papacy also authorized campaigns against Christian dissenters, including the Albigensian Crusade in southern France, and at times against political opponents. These campaigns belonged to a wider religious and political movement, but they were not interchangeable in purpose or circumstance.

Crusader states and regional societies

The principal Latin polities established in the Levant were the County of Edessa, the Principality of Antioch, the County of Tripoli and the Kingdom of Jerusalem. They were separate lordships, each with its own political interests, rather than parts of a single kingdom governed from Jerusalem. The rulers relied on local resources and alliances as well as military aid from western Europe. Truces and negotiations with neighbouring Muslim rulers were part of their political life, alongside warfare.

These states were also societies, not simply bases for foreign armies. Western European incomers were often called Franks in medieval accounts, whatever their precise origins. They lived among Arabic-speaking Muslims, Jews and Christian communities including Greek Orthodox, Armenian and Syriac Christians. The balance and character of these communities varied by place. Latin rulers and religious authorities held political power, while many local communities maintained their own religious practices and institutions. The arrangements were unequal: Jews and Muslims faced restrictions and taxation under Frankish rule.

Most people in the countryside worked the land, and agricultural dues helped support lords and institutions. Towns and ports had different economies, linking local production and trade with merchants from the Mediterranean world. Italian maritime communities provided ships and other assistance in return for commercial privileges. This mixture of local farming, urban trade, foreign settlement and military obligations helped sustain the states, with privileged merchant quarters in ports and dependent agricultural communities in the countryside.

How crusading armies were raised and sustained

There was no single army used for every crusade. Large expeditions could bring together nobles and their retinues, mounted knights, infantry and non-combatants. In the Levant, rulers also relied on their vassals, hired soldiers, forces sent from Europe and troops supplied by military orders. A vassal’s land could carry an obligation to provide military service, but this did not meet every need. Campaigning was costly: a knight might have to spend the equivalent of several years’ income to take part, and loans or donations could help cover the expense.

Armies had to travel, obtain supplies and maintain communications over long distances. Sea routes became especially important for moving people and provisions to the eastern Mediterranean. Italian cities including Genoa, Pisa and Venice supplied naval support in return for trade advantages. Crusade leaders and rulers also sought money through donations, church levies and other forms of taxation. A campaign’s fate could depend as much on supply, transport and political cooperation as on a battlefield victory.

In the Levant, warfare involved both field armies and the defence or capture of towns and fortresses. Sieges demanded time, labour and supplies, while a besieging army risked the arrival of relief forces. Defeat could have severe consequences for states that could not readily replace experienced troops. At the same time, campaigns did not always end in conquest: negotiated truces could secure access for pilgrims or settle control of territory for a limited period.

Preaching, recruitment and communication

Crusades required people to hear a call, decide to participate and organize travel and funding. Urban II’s appeal at Clermont spread through those who had heard it and carried the message elsewhere. Later campaigns made greater use of papal letters, councils, envoys and preachers. Bernard of Clairvaux, for example, preached the Second Crusade in France and Germany. Such communication could gather support across regions, but it did not give the papacy direct control over every participant or commander.

Recruitment reached beyond the warrior elite, although popes and other leaders sometimes tried to limit participation to people they considered suitable. Popular movements could become difficult to control. In 1096, crusading groups on the way east attacked Jewish communities in the Rhineland and Hungary, despite efforts by some churchmen to protect them. This violence shows that religious enthusiasm could have consequences far from the campaign’s declared destination, and that preaching did not ensure disciplined or peaceful conduct.

Vows, indulgences and papal authority

Taking the cross meant making a religious vow to join a campaign. Crusading appeals promised spiritual benefits, often described in terms of remission of sins or penance. The exact promise associated with Urban II’s original call is not reported consistently. Later papal documents set out the benefits more explicitly. The bull issued by Pope Eugenius III in response to Edessa’s fall in 1145 offered remission, protection for participants’ property and relief from interest charges and protection against creditors. Such provisions could make a distant expedition more feasible for those who had family, land or creditors at home.

Papal policy also adapted to changing circumstances. By the time of the Fourth Lateran Council in 1215, a person unable to travel could receive a full indulgence for financing a warrior’s journey, while donors who gave less could receive a partial one. Clerical income was taxed to fund campaigns. These measures helped connect religious commitments to administration and finance, but their use varied across expeditions. Crusading authority was never purely a matter of papal commands: rulers, nobles, church leaders and local communities all influenced whether and how a campaign proceeded.

Military orders and permanent defence

Military orders joined religious life to armed service. Members generally followed monastic ideals, including vows of poverty, chastity and obedience, although many members were laymen rather than ordained clergy. The Knights Templar developed around the armed protection of pilgrims. The Hospitallers grew from a charitable nursing community and took on military duties in the 1130s. The Teutonic Order began in the eastern Mediterranean before becoming closely involved in campaigns in the Baltic.

Orders offered a form of continuing military presence beyond the arrival and departure of individual crusading armies. They garrisoned fortresses, supplied soldiers and received donations of land and income across Europe. Their network of houses helped transfer resources to their eastern headquarters and supported their military and charitable work. The Hospitallers, for example, retained a hospital role as well as military responsibilities. These institutions were influential, but they were not simply armies: each had its own history, duties and relationships with rulers and local societies.

Later campaigns and the memory of crusading

The loss of the Levantine mainland did not end crusading. A crusading expedition attacked Alexandria in 1365, and a French and Burgundian force joined a campaign against the Ottoman Empire that ended in defeat at Nicopolis in 1396. The conquest of Granada by Castile and Aragon in 1492 ended Muslim political rule in Iberia; Portuguese and Spanish rulers also pursued crusading campaigns in North Africa. In the Baltic, campaigns continued into the fifteenth century. Papally sponsored Holy Leagues against the Ottoman Empire carried crusading forms of organization and purpose into the early modern period.

The familiar word crusade became established long after the first expeditions; medieval writers used a variety of terms for journeys, expeditions and the taking of the cross. Later memory also gave crusading new meanings. Some nineteenth-century histories treated the Levantine states through the lens of European colonial experience, an approach later historians challenged. In modern times, some Muslim thinkers, politicians and historians have used crusading history to discuss Western power and contemporary conflicts, while some Western political groups have invoked crusader imagery in anti-Muslim rhetoric. These modern uses placed medieval events within much later political arguments.