What the crusades were
The crusades were a series of military expeditions, mostly between the late eleventh and the late thirteenth centuries, that Western Christian leaders and the papacy authorized as acts of religious service. Most were aimed at Jerusalem and the eastern Mediterranean, but the same idea was later applied in Spain, the Baltic lands, southern France and elsewhere. The word “crusade” itself came into common use somewhat later than the first expeditions; participants spoke of pilgrimage, of “taking the cross,” and of an armed journey.
The numbering used today (First Crusade, Second Crusade and so on) is a later convenience. Historians do not always agree on how many crusades there were, and many expeditions fit no tidy number.
The call of 1095
In November 1095, Pope Urban II preached at a church council held at Clermont in France. The immediate background was a request for military help from the Byzantine emperor Alexios I, whose empire had lost much of Anatolia to Seljuk Turks after the defeat at Manzikert in 1071. Urban urged the knights of the West to go east, and he offered spiritual rewards to those who did. No complete record of his words survives, and the surviving accounts were written after the event, so the exact message is debated.
The response was far larger than the pope may have expected. Armies led by great nobles set out in 1096, and before them came poorly organized groups of ordinary people, some of whom attacked Jewish communities in the Rhineland along the way.
The First Crusade and the new states
The main armies crossed the Byzantine lands, took Nicaea in 1097, defeated a Turkish force at Dorylaeum, and besieged Antioch for many months, capturing it in 1098. They reached Jerusalem and took it in July 1099 after a short siege, with great bloodshed in the city. Afterward, crusader leaders set up territories along the coast and inland: Edessa, Antioch, Tripoli and the Kingdom of Jerusalem. Together these are known as the Crusader States, and they survived in changing forms for almost two centuries.
The twelfth century
The fall of Edessa to a Muslim ruler in 1144 prompted the Second Crusade (1147-1149), led by Louis VII of France and Conrad III of Germany. It failed to achieve its goals, and an attack on Damascus ended in retreat.
Over the following decades, Muslim Syria and Egypt came increasingly under one leadership, that of Saladin. In 1187 his army destroyed the main Frankish field force at the Battle of Hattin, and Jerusalem surrendered soon after. The shock produced the Third Crusade (1189-1192), joined by Richard the Lionheart and Philip II of France; the German emperor Frederick Barbarossa drowned on the way. The crusaders retook Acre and much of the coast, but not Jerusalem. A truce allowed Christian pilgrims to visit the city.
The thirteenth century
The Fourth Crusade (1202-1204) was diverted, in a chain of debts and promises involving Venice, to Constantinople, which was sacked in 1204. A Latin-ruled state replaced Byzantine rule there until the Greeks recovered the city in 1261. Other expeditions followed: the Fifth Crusade attacked Egypt, and the emperor Frederick II regained Jerusalem by treaty in 1229, though it was lost again in 1244.
Louis IX of France led two crusades, one to Egypt (1248-1254), where he was captured and ransomed, and one to Tunis in 1270, where he died. Muslim rule under the Mamluk sultans of Egypt steadily reduced the remaining Christian territories. The last major stronghold, Acre, fell in 1291.
Crusading beyond the Holy Land
Crusades were also launched against other targets. The Albigensian Crusade, from 1209, was directed at heretics in southern France. Campaigns in the Baltic, associated with the Teutonic Knights and others, aimed at pagan peoples. In Iberia, the long conflict known as the Reconquista was often described in crusading terms, and popes granted crusading privileges to those who took part.
The late medieval afterlife
After 1291, European rulers kept talking about new crusades and some were attempted, but most plans never left the page. In the fourteenth and fifteenth centuries, crusading was increasingly aimed at the expanding Ottomans in the Balkans. The defeat of a large crusading army at Nicopolis in 1396 and another at Varna in 1444 showed the limits of such efforts. Military orders such as the Knights Templar and the Knights Hospitaller were closely tied to the movement; the Templars were dissolved in 1312, while the Hospitallers continued for centuries.
Why the history is still argued over
Historians continue to debate how much religious devotion, family honor, land hunger and papal politics each explain about the movement, and how its legacy should be judged. What is generally agreed is that the crusades left lasting marks on Europe, the Byzantine world and the Muslim and Jewish communities that lived through them, and that the picture is more complicated than a simple clash of two civilizations.