The historiography of the Crusades is the study of history-writing and the written history, especially as an academic discipline, regarding the military expeditions initially undertaken by European Christians in the 11th, 12th, or 13th centuries to the Holy Land. This scope was later extended to include other campaigns initiated, supported, and sometimes directed by the Roman Catholic Church. The subject has involved competing and evolving interpretations since the capture of Jerusalem in 1099 until the present day. The religious idealism, use of martial force and pragmatic compromises made by those involved in crusading were controversial, both at the time and subsequently. Crusading was integral to Western European culture, with the ideas that shaped behaviour in the Late Middle Ages retaining currency beyond the 15th century in attitude rather than action.
From the 17th century historians began rejecting the religious motivations applied to crusading and instead examined the secular. The building of nation states led to the application of interpretations in support of this and fundamentally discrete from the religious sphere. This presented a challenge in reconciling the idealistic and the materialistic motives of the protagonists. The internationalism of crusading remained an obstacle to those historians wishing to project both the idea of crusading and the Crusades themselves as nationalistic precedents. Enlightenment thinkers considered the crusaders culturally inferior to themselves and Protestants considered them morally so.
By the 19th century the development of nationalism, colonial politics, and critical history increased interest in the subject for the purposes of entertainment and moralising. In the early 20th century a focus developed on the part crusades played as drivers of medieval conquest, economics, and the legacy they left. Crusading historiography continues to evolve and covers a wide range of issues.