A crusade preacher, participant in the Fifth Crusade (1217-1221), and historian.
Oliver became head of the cathedral school in Cologne in 1201. While studying in Paris, he was probably drawn into recruiting for the Albigensian Crusade around 1207. He was appointed to preach the Fifth Crusade throughout the archdiocese of Cologne in 1213 and attended the Fourth Lateran Council (1215). He and his co-workers soon became responsible for organizing crusade funding and departures in the archdiocese. Arriving in Acre (mod. ‘Akko, Israel) in the summer of 1217, Oliver joined others in urging the crusading army to attack Egypt. Throughout the crusade, he acted as the spiritual leader of the Frisian and German contingents and also wrote proselytizing letters to the sultan and learned men of Egypt. Oliver also reworked his newsletters to other crusade recruiters in Europe into an account of the campaign and the conditions and various peoples in the East, known as the Historia Damiatina. Widely popular, the work was quickly utilized by chroniclers in France, Germany, England, and the Low Countries. Both in its original form and as part of an anonymous work meant to complete the Historia Iherosolim- itana of Oliver’s colleague, James of Vitry, the Historia Damiatina was mined by authors of treatises intended for potential missionaries and crusaders, including the Speculum historiale of Vincent of Beauvais, dedicated to the crusader Louis IX, king of France.
Oliver also wrote other less well-known histories of the Holy Land and previous crusades, which drew on the histories of Fulcher of Chartres and William of Tyre: the Historia Terre Sancte,Historia de ortu Jerusalem et eius variis even- tibus, and Historia regum Terre Sancte. Oliver may have used his histories for apologetic and propagandistic purposes while recruiting for the delayed Crusade of Emperor Frederick II (1227-1229), which he promoted in collaboration with other reformers, including James of Vitry, Conrad, bishop of Hildesheim, and Conrad of Urach. Oliver’s interest in missions to Eastern Christians and Muslims later influenced Honorius III’s and Gregory IX’s efforts in this direction, and his knowledge of conditions in the East certainly affected the crusading plans of Frederick II. Oliver also worked closely with the grand master of the Teutonic Order, Hermann von Salza, to obtain papal and imperial privileges to strengthen the order for the approaching imperial crusade and the struggle against pagans in the Baltic region. Oliver was elected bishop of Paderborn in April 1225, but resigned in September after being appointed cardinal of Santa Sabina, a position he held until his death.