COMNENUS (Μανουὴλ ὁ Κομνηνός), emperor of Constantinople from 1145 to 1180, was the fourth son of John II, and was born about A.D. 1120. Two of his elder brothers, Alexis and Andronicus, both died before their father, and a special declaration of the emperor appointed Manuel as his successor, to the prejsliice of his third son, Isaac Sebastocrator. As soon as Manuel ascended the throne, he surrounded himself with the bravest warriors of the West, and soon became foremost even among them for his courage. His reign was a succession of wars, sometimes in Asia, sometimes in Europe. Conrad III and Louis VII having informed him that they were preparing a new crusade, Manuel, although apparently disposed to help them, gave secret information to the Turks of the approaching danger.
The relation which Manuel Comnenus sustained to the Church of Rome is of special interest to us. His Latin subjects he treated with kindness, embellished their churches, and readily did all they asked of him. This generous disposition on the part of Manuel Comnenus towards the Latins encouraged pope Hadrian IV (1154-1159) to make proposals for a union of the Eastern with the Western Church, but the plan failed of success because of the objections of the Greek patriarch to acknowledge the supremacy of the pope of Rome. SEE GREEK CHURCH. After Hadrian's death Manuel entered into correspondence with Alexander III, declared himself in favor of the Crusades, and offered assistance. The German emperor, Frederick I, had taken sides with the rival pope Victor, and Manuel embraced this opportunity to urge upon Alexander the claims of the Greek emperor to the Roman crown, promising in return to aid the pope in establishing the papal power in all Italy, and in the union of the Eastern and Western Church. So long as the pope was in danger from the invading Allemanni, he acted as if he felt inclined to acknowledge to the true representative of Constantine and Augustus. But after the establishment of peace and friendship with Frederick, Alexander "spoke a more peremptory language, confirmed the acts of his predecessors, excommunicated the adherents of Manuel, and pronounced the final separation of the churches, or at least the empires of Constantinople and Rome" (Gibbon, v, 491). Manuel died Sept.24, 1180. He is said to have been deeply versed in theology, but "was certainly rather a great talker than a great thinker on religion." See Smith, Dict. of Gr. and Romans Biog. s.v.; Lebeau, Hist. du Bas-Empire (Paris, 1834), 16:63 sq.; Wetzer u. Welte, Kirchen-Lexikon, s.v.