Justinian I: A Legendary Byzantine Emperor Early Life and Rise to Power Justinian I, born Peter Savvatios in the village of Tauresium in CE, hailed from an Illyrian peasant family. Upon his adoption by his childless uncle, Emperor Justin I, he rose swiftly through the ranks of the military, becoming the magister equitum et peditum praesentalis, commander of the capital&;s garrison.