The Byzantine Empire effectively began to come into shape when the Roman Empire was divided into Eastern and Western portions in the 3rd century. Many early Byzantine emperors also ruled over the Western Roman Empire. After the fall of the Western Roman Empire, the Byzantine emperors such as Justinian I would try to regain the territories lost in the west and append them to the Byzantine Empire.
Constantine I became the sole ruler of the Western Roman Empire as well as the Byzantine Empire after winning a number of civil wars by 324. It was during his period that Christianity as a religion was accepted within the borders of Rome.
It was during his reign that Byzantium became a very important city of the Empire. He named the city “Constantinople” after himself and some historical sources cite him as the first Christian emperor. His tolerance of Christianity was to leave a lasting impact on the identity of Europe and specifically that of the Byzantine Empire.
After his death, the Emperorship transitioned to his own sons. Throughout the history of the Byzantine Empire, Constantine I was revered as a paragon of Christian virtues and as an exemplary leader.
Theodosius I ruled the Byzantine Empire from 379 to 392 and the Western Roman Empire as well from 392 to 395. It was during his reign that Nicene Christianity was formally accepted as the state church of the Byzantine Empire. It was also during his reign that a number of pagan temples in the Hellenistic regions of the Byzantine Empire were demolished.
Theodosius banned pagan rituals within the Empire in 393, including the Olympics and had these bans enforced strictly throughout the Empire. During his reign, non-Nicene Christianity was suppressed the same as other pagan religions. He died in 395 and left the Empire amid instability.
Leo I ruled the Byzantine Empire from 457 to 474. His reign was marked by relative stability in the Empire and consolidation of its territories. He ushered in a number of reforms which helped the Empire stand back on its feet and also began to send aid to the Western Roman Empire which was nearing its demise.
During his period, many of the territories lost by the Western Roman Empire were recovered and consolidated under the Byzantine Empire. He also undermined the control of the Goths over the Byzantine army and restored the Emperor’s power over it. Although respected for his capable administration in the early part of his reign, he made many costly mistakes towards the end of his emperorship and became unpopular.
Justinian I ruled the Byzantine Empire from 527 to 565. His reign was marked by his persistent attempts to restore the original glories of the Roman Empire and to regain the territories lost by the Empire in its former western half. His attempts succeeded significantly and Rome, Italy, Sicily, portions of North Africa and the southern Iberian regions were appended to the Empire’s territories.
Consequently, Byzantine Empire became the most dominant power over the waters of the western Mediterranean. During his reign, the Emperor’s rule over the state Church was acknowledges and formalised. He was a great patron of arts and erected masterpieces of ecclesiastical architecture, including the Hagia Sophia. He died in 565 after a long reign which is often considered one of the periods of golden revival in Byzantine history.