Crusade

The crusading movement began when Pope Urban II called for an armed expedition to recover Jerusalem and aid the Byzantine Empire against Turkish advances in a sermon preached at the Council of Clermont in 1095, an appeal that drew a much larger and more socially varied response than the pope had likely anticipated and resulted in the First Crusade's capture of Jerusalem in 1099. Central to the crusading institution as it developed was the indulgence, a remission of the temporal punishment due for sin granted by the church to those who undertook the campaign with proper contrition, which gave crusading a specific and unusual theological status among medieval Christian penitential practices, an act of arms treated as spiritually equivalent to pilgrimage.

Historians conventionally number a sequence of major crusades to the eastern Mediterranean running from the First in 1096 to the Ninth in the late thirteenth century, but the papacy also authorized crusades against targets much closer to home and considerably more diverse than the recovery of Jerusalem, including the Albigensian Crusade against the Cathars in southern France, the Baltic and Northern Crusades against pagan peoples, and crusades called against Christian political rivals of the papacy itself.

Historians of the crusades have argued for decades over how broadly the term should be defined, a debate with real consequences for what counts as a crusade at all and how many there ultimately were. Jonathan Riley-Smith and other scholars associated with what is sometimes called the pluralist position argue that any campaign meeting the crusading movement's specific institutional criteria, papal call, the taking of a vow, and the grant of crusading indulgences, counts as a crusade regardless of its target, which extends the category well beyond the eastern Mediterranean campaigns to include the Baltic, Iberian Reconquista and internal European crusades. A narrower, more traditionalist reading, associated with earlier generations of crusade scholarship, restricts the term more closely to the sequence of expeditions aimed at recovering or defending Jerusalem and the Holy Land specifically.

Christopher Tyerman's scholarship has further complicated the picture by questioning how coherently contemporaries themselves understood crusading as a single unified concept even within its own medieval period, arguing the idea of a crusade as one continuous movement was itself partly a later historiographical construction imposed on a more varied and improvised set of medieval military and religious undertakings.