Chronicler of the First Crusade (1096-1099) and the early years of Frankish Outremer.
Born into a noble but obscure French family, Guibert entered the abbey of Saint-Germer-en-Fly as an adolescent, and in 1104 he was elected abbot of Nogent-sous-Coucy. The outlines of his life are known from his autobiography. An accomplished Latinist, he cultivated a difficult style that failed to please either contemporaries or posterity. He was one of three key Western churchmen to rework the popular account of the First Crusade, the Gesta Francorum, and to fashion from it the elements of a crusade theology in his revealingly named and unjustly neglected Dei Gesta per Francos (1109). His extraordinary knowledge and extreme prejudice is visible from the opening of Book I, which gives some account of the religious background to the crusade, starting with the heresies of Pelagius, Arius, and Manes and proceeding through the degeneration of the Greek Church.
His account of the Prophet Muhammad and the “pagan heresy” of Islam would offend a Muslim but is striking for its rarity in a Christian source of this period. He preserves a letter of the Byzantine emperor Alexios I Komnenos to Duke Robert I of Flanders, detailing the menace from the Turks faced by the empire and its holy places.
Dei Gesta goes far beyond its main source in providing additional material, both written (from Fulcher of Chartres and the letters of Anselm of Ribemont) and oral. It provides unique insights into medieval mentality in its disdain of the poor and their leader Peter the Hermit, and in its attempt to exculpate fallible nobles such as Stephen of Blois.