Latin emperor of Constantinople (1217).
A member of the influential French Courtenay family, Peter was a great-grandson of King Louis VI of France and a cousin of King Philip II Augustus. Through his first wife he became count of Auxerre and Tonnerre. By his second wife, Yolande of Flanders, sister of the Latin emperors Baldwin I and Henry, Peter became marquis of Namur. He succeeded as Latin emperor of Constantinople on the death of Emperor Henry (1216), when the barons of the empire appointed Conon of Béthune as regent and invited Peter and Yolande to take the throne. After investing their oldest son, Philip, with the marquisate of Namur, Peter and Yolande set out from Namur with around 160 knights and 5,500 sergeants to Rome, where they were crowned outside the city walls by Pope Honorius III in the church of St. Laurence on 17 April 1217. Previously (11 April) they had guaranteed on oath to respect the conventions made between the previous Latin emperors, the barons of Constantinople, and the Venetians.
Peter’s first political act (9/16 April) was to invest William of Montferrat and his half-brother Demetrius (son of Boniface of Montferrat and Maria of Hungary) with the kingdom of Thessalonica; he thus reversed the policy of his predecessor, Henry of Flanders, toward this kingdom. From Brindisi, the Venetians transported Peter and his troops to Dyrac- chion (mod. Durrës, Albania), which he was to conquer for Venice, before traversing the territory of the ruler of Epiros, Theodore Komnenos Doukas, and then following the Via Egnatia to Constantinople. Yolande reached Constantinople by sea, but Peter’s ill-conceived plan went wrong when he had to abandon the siege of Dyracchion. Then, in the mountains of Albania, he was ambushed by Theodore, who had promised safe passsage for the emperor and his troops to the papal legate John Colonna who was accompanying him. Peter was taken prisoner and almost all his troops perished. Colonna was freed after pressure by the pope. By 1218, it became generally accepted in the West that Peter had died in prison.
Peter’s capture and death were a serious blow to the Latin Empire, while Theodore of Epiros established himself as a contender for the Byzantine throne. Two of Peter’s sons, Robert and Baldwin II, succeeded him in turn as Latin emperors. His daughters, Agnes and Marie, married, respectively, Geoffrey II, prince of Achaia, and Theodore I Laskaris, emperor of Nicaea.