schism · 484–519 · Constantinople
The first formal breach between Rome and Constantinople (484–519): Zeno's Henotikon, drafted with patriarch Acacius to appease the anti-Chalcedonians, passed over the council of 451 in silence; Pope Felix III excommunicated Acacius, and for thirty-five years the sees were out of communion — healed only when Justin I accepted the formula of Pope Hormisdas (519).
Zeno's Henotikon: buying back the anti-Chalcedonians by passing over Chalcedon in silence.
Thirty-five years out of communion — Rome excommunicating Acacius, Constantinople erasing popes from the diptychs — healed by the formula of Hormisdas (519).