476–477 (Basiliscus's Encyclical); 482 (Zeno's Henoticon) – 519 (end of the Acacian Schism)

Zeno's Henoticon and the Acacian Schism

Seeking to reconcile the Orthodox and the Monophysites, the usurper Basiliscus issued an encyclical letter in 476–477. It anathematized the Council of Chalcedon and Leo's "Tome."

Zeno, restored to power, issued a compromise decree in 482 on the advice of Patriarch Acacius of Constantinople – the "Henoticon" ("decree of union"). It reaffirmed the Nicene Creed and Cyril's anathemas and condemned both Nestorius and Eutyches. But it passed over in silence the question of Christ's "natures" and ambiguously mentioned "Chalcedon or any other council."

The compromise satisfied neither strict Monophysites nor Chalcedonians, but it caused a sharp break with Rome. The pope declared that the emperor had no right to decide matters of faith, and Felix III excommunicated and deposed Acacius. The so-called Acacian Schism between Rome and Constantinople lasted until 519. That year Emperor Justin I and Pope Hormisdas restored communion on Rome's terms, effectively reaffirming Chalcedon.