<P> In 272, Emperor Aurelian finally managed to reclaim Palmyra and its territory for the empire . With the East secure, his attention turned to the West, invading the Gallic Empire a year later . Aurelian decisively defeated Tetricus I in the Battle of Châlons, and soon captured Tetricus and his son Tetricus II . Both Zenobia and the Tetrici were pardoned, although they were first paraded in a triumph . </P> <P> Diocletian was the first Emperor to divide the Roman Empire into a Tetrarchy . In 286 he elevated Maximian to the rank of augustus (emperor) and gave him control of the Western Empire . In 293, Galerius and Constantius Chlorus were appointed as their subordinates (caesars), creating the First Tetrarchy . This system effectively divided the Empire into four major regions, as a way to avoid the civil unrest that had marked the 3rd century . In the West, Maximian made Mediolanum (now Milan) his capital, and Constantius made Trier his . In the East, Galerius made his capital Sirmium and Diocletian made Nicomedia his . On 1 May 305, Diocletian and Maximian abdicated, replaced by Galerius and Constantius, who appointed Maximinus II and Valerius Severus, respectively, as their caesars, creating the Second Tetrarchy . </P> <P> The Tetrarchy collapsed after the unexpected death of Constantius in 306 . His son, Constantine the Great, was declared Western Emperor by the British legions, but several other claimants arose and attempted to seize the Western Empire . In 308, Galerius held a meeting at Carnuntum, where he revived the Tetrarchy by dividing the Western Empire between Constantine and Licinius . However, Constantine was more interested in conquering the whole empire than he was in the stability of the Tetrarchy, and by 314 began to compete against Licinius . Constantine defeated Licinius in 324, at the Battle of Chrysopolis, where Licinius was taken prisoner, and later murdered . After Constantine unified the empire, he refounded the city of Byzantium in modern - day Turkey as Nova Roma ("New Rome"), later called Constantinople, and made it the capital of the Roman Empire . The Tetrarchy was ended, although the concept of physically splitting the Roman Empire between two emperors remained . Although several powerful emperors unified both parts of the empire, this generally reverted in an empire divided into East and West upon their deaths, such as happened after the deaths of Constantine and Theodosius I . </P> <P> Constantius was born in 317 at Sirmium, Pannonia . He was the third son of Constantine the Great, the second by his second wife Fausta, the daughter of Maximian . Constantius was made Caesar by his father on 13 November 324 . The Roman Empire was under the rule of a single Emperor, but, with the death of Constantine in 337, the empire was partitioned between his surviving male heirs . Constantius received the eastern provinces, including Constantinople, Thrace, Asia Minor, Syria, Egypt, and Cyrenaica; Constantine II received Britannia, Gaul, Hispania, and Mauretania; and Constans, initially under the supervision of Constantine II, received Italy, Africa, Illyricum, Pannonia, Macedonia, and Achaea . The provinces of Thrace, Achaea and Macedonia were shortly controlled by Dalmatius, nephew of Constantine I and a caesar, not an Augustus, until his murder by his own soldiers in 337 . The West was unified in 340 under Constans, who was assassinated in 350 under the order of the usurper Magnentius . After Magnentius lost the Battle of Mursa Major and committed suicide, a complete reunification of the whole Empire occurred under Constantius in 353 . </P>

Which ostrogoth helped break the last of rome's power