Crusades against Christians

Holy wars were fought in northern France, against King Roger II of Sicily, various heretics, their protectors, mercenary bands and the first political crusade against Markward of Anweiler.

[1] Christian holy war had a long history pre-dating the 11th century when papal reformers began equating the universal church with the papacy[clarification needed].

Later, Pope Gregory VII and his militia Sancti Petri considered fighting for the papacy as penitential; death brought salvation.

Late 11th century works of crusader theory by Anselm of Lucca and Bonizo of Sutri focused on heretics and schismatics rather than infidels.

The First Crusade encouraged further holy wars, peacekeeping in northern France, papal fighting with King Roger II of Sicily in the 1120s and 1130s, and against various heretics, their protectors, and mercenary bands in the 1130s and 1170s.