Constantine the Great, a monarch that stands out during Rome's decline as one who tried to put things back together. Flavius Valerius Constantinus became co-Augustus in 306 and later became Caesar. He re-united the Roman Empire and granted religious toleration to the Christians after the battle of Milvian Bridge in 312. He later became Rome's first Christian emperor. He helped the Pope and bishops clearly define the doctrines of Christianity and later moved the capital east to his city of Constantinople. After the execution of Lucinius he became sole emperor and was known as Constantine the Great. He died on May 22, 337 AD.
Theodosius the Great was the last Roman Emperor to rule both the east and the west. Flavius Theodosius became Caesar in 379 after a successful career as a general. He immediately took action to unite and defend the Roman Empire, momentarily turning back much of the decay that had crept in. He defeated all usurpers and famously made Rome a totally and fully Christian (specifically Catholic) empire, finally outlawing all pagan religious practices. He also once did public penance at the insistance of Saint Ambrose over a massacre his troops had committed, showing himself to be a devoted Christian. Known as Theodosius the Great, he died in 395.
Julius Nepos can accurately be called the last actual ruler of the Western Roman Empire. A renowned soldier and the husband of the neice of Emperor Leo of the East, Julius Nepos became Emperor in 474. He established himself in Dalmatia but lost most of Gaul (France) to the Goths. The Western Empire was, by this time, falling apart and in a state of near anarchy as barbarian tribes pillaged almost at will. His greatest mistake was making Orestes, former aid to Attila the Hun, his "Master of Soldiers". Orestes promptly rebelled against Nepos and drove him from Ravenna to Dalmatia. He never re-took the throne and died in 480 AD.
Romulus has the dubious honor of being "the last Roman Emperor" though his reign was largely symbolic. The real power behind the throne was his father Orestes. His father's main concern was securing foreign recognition of his son's throne. Because he was only a boy when placed on the throne, he was known as Romulus Augustulus or "little Augustus". The East mostly continued to recognize Julius Nepos as the legitimate Emperor of the West. Orestes eventually lost power by the same means he took it. His primary officer, Flavius Odoacer, led his mercenary army to depose and exile Romulus in 476. He died between 507-511.
Justinian came to the throne of the East Roman or Byzantine Empire in 527, immediately causing a stir by his marriage to the actress Theodora (a girl with a reputation). He immediately set about re-conquering the West from the barbarians, and for a time seemed to restore much of the old glory of Rome, with considerable help from his General Belisarius though there were continued east/west disputes with Pope Vigilius. His Justinian Code made him one of the great lawgivers of the world, combining Roman law with what was still largely a Greek Empire. He also built the magnificant Hagia Sophia in Constantinople. No other eastern emperor could match him, but his wars and monuments left the country drained.
Zoe was the daughter of Emperor Constantine VIII and for 26 years her successive husbands served as the Byzantine Emperors between 1028 and 1041. Byzantine power was removed from it's last hold in Italy and there was something of a power vaccum during this time. Her husband Michael V imprisoned her shortly after their marriage, but her popularity with the loyal people forced her release. Her last husband was Emperor Constantine IX Monomachus.
Constantine XI Palaeologus was the last Emperor of the Eastern Empire, coming to the throne in 1449, though by that time it had been reduced to simply the city of Constantinople. The walls that had protected the city for so long proved to be no defense against the Turkish bombards. At this point, the Byzantines were not even willing to defend themselves and Constantine had to rely on Western troops from Genoa, Venice and Spain. The siege began in 1453 at the command of the Turkish Sultan Mohammed II. Constantine himself fought desperately as his city was crushed by the superior Muslim forces and the last emperor fell with his men never to be recovered.
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