From the LCMS website:
Justinian was emperor of the East from A.D. 527 to 565 when the Roman Empire was in decline. With his beautiful and capable wife, Theodora, he restored splendor and majesty to the Byzantine court. During his reign the Empire experienced a renaissance, due in large part to his ambition, intelligence, and strong religious convictions. Justinian also attempted to bring unity to a divided church. He was a champion of orthodox Christianity and sought agreement among the parties in the Christological controversies of the day who were disputing the relation between the divine and human natures in the Person of Christ. The Fifth Ecumenical Council in Constantinople in A.D. 533 was held during his reign and addressed this dispute. Justinian died in his eighties, not accomplishing his desire for an empire that was firmly Christian and orthodox.