Under this agreement, Baldwin, Count of Flanders and Hainault, was created emperor (1204-05). The idea of the Roman system, which, despite the passage of centuries devoted to the triumphs of the barbarians, had impressed itself on Europe, was seen in the emperor's letter to the Roman pontiff, in which he congratulated him on the restoration of his authority in the East. The defeat and captivity of Baldwin in a war against the Bulgarians, and his subsequent death, placed the crown on the head of his brother Henry (1205-16). With him the imperial house of Flanders became extinct, and Peter of Courtenay, Count of Auxerre (1217-19), assumed the empire of the East. Peter was taken captive by Theodore, the legitimate sovereign of Constantinople, and his sons Robert (1221-28) and Baldwin II. (1228-37) reigned in succession. The gradual recovery of their empire by the legitimate sovereigns of the East culminated in the capture of Constantinople by the Greeks (1261). The line of Latin sovereigns was extinct. Baldwin lived the remainder of his life a royal fugitive, soliciting the Catholic powers to join in his restoration. He died in 1272. From the days of the Emperor Heraclius the Byzantine Empire had been most tranquil and prosperous when it could acquiesce in hereditary succession. Five dynasties--the Heraclian, Isaurian, Amorian, Basilian, and Comnenian families--enjoyed and transmitted the royal patrimony during their respective series of five, four, three, six, and four generations. The imperial house of Comnenius, though its direct line in male descent had expired with Andronicus I. (1185), had been perpetuated by marriage in the female line, and had survived the exile from Constantinople, in the persons of the descendants of Theodore Lascaris. Michael Palæologus, who, through his mother, might claim perhaps a prior right to the throne of the Comnenii, usurped the imperial dignity on the recovery of Constantinople, cruelly blinded the young Emperor John, the legitimate heir of Theodore Lascaris, and reigned until 1282. His career of authority was notable for an attempt to unite the Greek and Roman churches--a union which was dissolved in 1283--and his instigation of the revolt in Sicily, which ended in the famous Sicilian Vespers (March 30, 1282), when 8,000 French were exterminated in a promiscuous massacre.