The Acacian schism, between the Eastern and Western Christian Churches lasted thirty-five years, from 484 to 519. It resulted from a drift in the leaders of Eastern Christianity toward Miaphysitism and Emperor Zeno's unsuccessful attempt to reconcile the parties with the Henotikon.
In the events leading up to the Schism, Pope Felix III wrote two letters, one to Zeno and one to Acacius, Patriarch of Constantinople, reminding them of the need to defend the faith without compromise, as they had done previously.
When John Talaia, exiled from Alexandria, arrived in Rome and reported on what was happening in the East, Felix wrote two more letters, summoning Acacius to Rome to explain his conduct. The legates who brought these letters to Constantinople were imprisoned as soon as they landed and forced to receive Communion from Acacius as part of a Liturgy in which they heard Peter Mongus and other Miaphysites named in the diptychs. Felix, having heard of this from the Acoemeti monks in Constantinople, held a synod in 484 in which he denounced his legates and deposed and excommunicated Acacius.
Acacius replied to this act by striking Felix's name from his diptychs. Only the Acoemeti in Constantinople stayed loyal to Rome, and Acacius put their abbot, Cyril, in prison. Acacius himself died in 489, and his successor, Flavitas (or Fravitas, 489–90), tried to reconcile himself with Rome, but refused to give up communion with Miaphysites and to omit Acacius's name in his diptychs. Zeno died in 491; his successor, Anastasius I (491–518), began by keeping the policy of the Henotikon, though himself a convinced Miaphysite. After Anastasius's death his successor, Justin I, immediately sought to end the schism with Rome, a goal shared by the new Patriarch of Constantinople, John II. The reunion was formalized on Easter, March 24, 519.
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- Acacian Schism, OrthodoxWiki