The Triumph
In 311 Galerius suddenly died. Licinius transferred to become Augustus of the east and recognised Constantine as Augustus of the west. Maximian operated as a general acting for Constantine against his own son across the border between Italia and Provence but in 310 he, once again, declared himself Augustus.
Constantine by now had secured the Gallic empire and quickly defeated Maximian and instructed him to commit suicide.
For the next decade the civil wars continued. Constantine eliminated Maxentius( 312) Licinius eliminated Maximinus Daia (313) and Constantine eliminated Licinius(324)
Thus on this occasion the gallic emporer now controlled the whole of the Roman World. At least temporarily the Celts were content. It did not last.
Constantine moved his capital to Byzantium where he founded the city of Constantinople. It was a move to the east which once again alienated the Celts
The Tragedy
Constantine showed his priorities by appointing his eldest two sons as caesars of the west.
His eldest son Crispus was a great success and eminently acceptable as sucessor to his father as High King. He married Helen and had a son in 322. Crispus was called to the east, against the wishes of his court, to assist his father in his battles with Licinius. Despite being supremely successful he never returned. He was murdered by Constantine for having a sexual relationship with his step mother Fausta, who was also executed.
His successor as Emporer of the West was Constantine’s eldest son by Fausta Constantine II. The rest of the empire was divided amonst Fausta’s other sons, Constans and Constantius. On Constantine’s death, the three son’s organised a bloodbath murdering every other descendant of Constantius Chlorus and Constantine – men women and children. There were three survivors, very young children , who it was assumed could have no chance of disturbing future succession.
The Inequalities
The details of the subdivision of the empire, to his family were recorded and became the continuing basis of the Subdivision of East and West. The inherent inequalities became clearer. To take just one example. The Roman Empire was underpinned by the granaries of Egypt and Africa ( the Province not the Continent).
Egypt, the most reliable source of grain, was now assigned to the Eastern Empire and Africa To the West. In practice Egypt was controlled by the eastern Caesar, not the Augustus. However as the senior emporer, the Augustus was still able to demand deliveries of grain to the major cities of the East. The city of Rome was however deprived of Egyptian grain.
In the West the major granaries of Africa were governed by the Augustus. The Caesars realm, the Gallic empire of Britain, Gaul and Hispania received very little, perhaps no grain. Despite this it was the Western Caesar who was expected to maintain the empires most threatened frontier, along the Rhine. consideration of any other source of wealth produced similar disparaties It continually reinforced the concept ofan indepenent empires.
The Conflict
Fuelled by jealousies caused by these and other inequities, the brothers then set about killing each other. Constantine II invaded Italy and was ambushed and killed by Constans. Constans lost the respect of everyone including the army. He was overthrown and murdered by Magentius, a Celt and a Briton.
Twelve moths in later in 351 Constantius then invaded Gaul and defeated Magentius. The battle of Mursa Major was a catastrophy for both sides, for both empires.
Often reports of such events made exaggerations but even conservative estimates put the serious casualties at 50,000. Neither empire had time to recover and although the empire was once more united Constantius immediately retired to the east leaving behind as emporer, his cousin Gallus, a survivor of the family massacre who had taken no part in the recent battle, was immature and lacking in confidence. The Celts no longer had a high king who was acceptable to them.
Not only that but the losses at Mursa Major left them in the west and north hardly able to defend themselves.
Disintegration
In the winter of 367 Britain itself descended into chaos. It would appear that the British had decided to rid themselves of Roman rule. The Roman provinces were attacked from every side Scotti from Hibernia (Ireland), Picts from Caledonia, and Saxons from Germania. Local legions rebelled and the British tribes acted not against the invaders but in concert with them, to destroy Roman control. It is called “the great conspiracy” and it took the central empire more than a year to re- establish order.
In this period the first contraction of Romano-Britons westward to Wales and Cornwall and strathclyde began.
Macsen
The leader of the Roman army of reclamation was Comes Theodosious from Hispania. With him came his son, the future Emporer Theodosius, and a mystery man Magnus Maximus, who became known to the Romano-British in wales as Macsen Weldig.
There are many different views on who Macsen might have been. Some geneologies show him as the son of Constantius II but Constantious II appointed not one but two Caesars in the period 351-355, both his cousins( Gallus was followed by Julian)
These appointments do not make sense if Constantius had a son unless he was very young- too young to be Macsen.
An alternative history says he was an unknown from Hispania, possibly another son of Comes Theodosius.
There is another alternative which would have made him an instant candidate for high king. It is possible that he was the son of Crispus and therefore the grandson of Constantine who had escaped to Hispania when his father was killed. Crispus son would have been about forty-six at the time of the great conspiracy not an unreasonable age to be hailed as high king.
Macsen as Emperor
Macsen left Britain for ten years. He served with Comes Theodosius in for several years in Africa and on the Danube. Count Theodosius was executed in Catharge in 375. Macsen fled to britain and count Theodosius son to the family home in Hispania
Eventually Count theodosius son was invited to become Emperor in 379 in the east but Gratien held on to the West
Whoever he was Macsen once again breathed life into the gallic empire. Within three years he had the support of the whole of the Gallic empire, Britain, Gaul and Hispania. Once again he set up his capitol at Trier and when the Emporer Gratien advance to meet him Macsen won a great victory close to Paris.
In 384 Macsen was recognised as emporer in the west. Perhaps inspired by the example of Constantine he pressed on into Dalmatia but was defeated at the crossing of the save river by Stilicho, Comes Stabuli of Theodosius I, a vandal who was the only man to be a Magister Militum simultaneously in both eastern and western Empires. Macsen retreated but was ultimately captured and executed.
Welsh history says he was the founder of all the late British royal houses from Brittany to Strathclyde.
Eugenius
His role in Britain was assumed by his son Eugenius
Theodosius appointed a Frank, Arbogast as magister militorum in the west acting for Valantinian II younger son of Valantinian. Arbogast asumed complete control, and in 392 murdered Valantinian and raised Eugenius, who British records show as a son of Macsen to the purple.
Once again Stilicho advanced west and in 393 swept away both Arbogast and Eugenius.
Roman Withdrawal
In the same year another son of Macsen, Doinotus claimed the high kingship but he was eliminated by Chyrsetius during a visit which was specifically intended to withdraw all Roman Legions from Britain, many of which were almost entirely composed of British legionaires.
From 395 to 396 Under the leadership Macsen’s british wife “ Helen of the Hosts” the Romano-British made a fortress of wales building fortresses at Caenarvon, Caeleon and Camarthen and repairing and extending the roman roads which connected the three strong points.
Helen died in 396