Justinian assembles a vast army early in…

Justinian assembles a vast army early in the 550s, composed not only of Romans but also of barbarians, including Lombards, Heruli, and Gepids, as well as Persian deserters.

The emperor intervenes repeatedly, and unsuccessfully, in theological quarrels to reconcile eastern Monophysites and western Catholics.

In 553, he convokes the Second Council, or Synod, of Constantinople, the fifth ecumenical council, to condemn the Nestorian writings called the "Three Chapters."

The council, dominated by the emperor, proscribes Nestorianism and reconfirms the doctrine that Christ's two natures, one human and one divine, are perfectly united in one person.

Pope Vigilius at first defends the “Three Chapters,” but later accepts the council's ruling.

The Council condemns “Origenism,” the teachings of influential third-century theologian and mystic Origen; Justinian issues a decree banning the doctrine of reincarnation and mandating the removal from religious documents of all veiled references to preexistence.

The Council also condemns the teachings of Greek theologians Theodore of Mopsuestia, Theodoret of Cyrrhus and Ebas of Edessa; and reverses many decisions made by the fourth ecumenical council.

This causes further schisms and heresies of monoenergism and monothelitism.