The Acacian Schism (484–519) was caused by a change of policy on the part of the Patriarch of Constantinople, Acacius (472–489), who despite his intimacy with the Monophysites had opposed the anti-Chalcedonian encyclical of the Emperor basiliscus in 475. Upon the restoration of the Emperor Zeno (August 476), he collaborated in the deposition of the Monophysite bishops, including Peter the Fuller of Antioch and John Codonatus of Apamea. In 479 he consecrated the Chalcedonian Calandion as bishop of Antioch at the emperor's behest and drew a protest from Pope simplicius (468–483) for interfering in another patriarchal jurisdiction (Epist. June 22, 479).
In 482, in concert with Peter Mongus, he composed a doctrinal statement called the henoticon, or Decree of Union, which Zeno promulgated for the province of Egypt. It was intended to conclude the Christological disputes by citing the authority of the first three ecumenical councils, condemning Nestorius and Eutyches, but it did not mention the natures in Christ. Contrary teaching, "be it of the Council of Chalcedon or any other council," was condemned. Though the symbol of Chalcedon and Leo's Tome were not rejected, anti-Chalcedonians were admitted to communion, and Peter Mongus was reinstated as patriarch in Alexandria.
Pope felix iii wrote a letter of protest to Acacius, then excommunicated him in a Roman synod (July 28, 484) when Acacius recognized Peter Mongus at Alexandria. When the excommunication was reiterated in 485, Acacius erased the name of Felix from the diptychs. The two successors of Acacius, Fravita (490) and Euphemius (490–495), were not hostile to the decrees of Chalcedon. They announced their election to the pope for recognition; but Felix demanded that Acacius's name be struck from the diptychs, and relations were again suspended between Rome and Constantinople. The Patriarch Euphemius, having forced the new Emperor anastasius i (491–518) to accept the decisions of Chalcedon before his accession to the throne, attempted to heal the rupture with Pope gelasius (492–496), but without success since the new pope renewed the demand made by Felix. Meanwhile acceptance of the Henoticon, though not universal among the Monophysites, was considered an anti-Chalcedonian gesture. Gelasius, however, entered relations with Constantinople through an embassy sent by the Roman senate (492 and 494); but his successor, anastasius ii (496–498), proved adamant in the request for the removal of Acacius's name from the diptychs.
Emperor Anastasius was encouraged in his anti-Chalcedonian policy during the three-year sojourn in Constantinople (508–511) of the Monophysite propagandist severus, the future patriarch of Antioch (512–518) and a fervent supporter of the Henoticon. The emperor published his Type, or formula for union, which he attempted to impose upon the Chalcedonian Patriarch, Flavian of Antioch (510). In 512 Pope symmachus responded to an imperial letter that attempted, among other accusations, to charge him with favoring Manichaeism.
When the rebel general Vitalian forced the emperor to agree to call a council at Heraclea with the pope presiding, Anastasius was compelled to enter into relations with Rome. But after the defeat of Vitalian, legations sent to Constantinople in 515 and 517 by Pope hormisdas were unsuccessful. However the advent of justin i occasioned immediate negotiations between Hormisdas and the pro-Chalcedonian emperor. The schism was brought to an end on March 28, 519, when Patriarch John in a letter to the pope indicated his acceptance of the formula of Hormisdas and the removal of the names of Zeno and Acacius as well as the latter's five successors from the diptychs. Opposition throughout the East endured only briefly.
Bibliography: e. schwartz, Publizistische Sammlungen zum Acacianischen Schisma (Abhandlungen der Akademie der Wissenschaften NS 10; 1934). f. hofmann, Das Konzil von Chalkedon, ed. a. grillmeier and h. bacht (Würzburg 1951–54). 2:43–94. r. haacke, ibid. 117–146. h. bacht, ibid. 266–291. p. charanis, Church and State in the Later Roman Empire (Madison, Wis. 1939). s. salaville, "L'Affaire de l'Hénotique," Échos d'Orient 18 (1916–19) 255–266, 389–397; 19 (1920) 49–68, 415–433. l. salaville, Dictionnaire de théologie catholique, 6.2: 2153–78. e. stein, Histoire du Bas-Empire, tr. j. r. palanque 2:24–39, 224–228.