Rather than pursuing his opponent, Constantius then turned his attention to securing the Danubian border, where he spent the early months of 352 campaigning against the Sarmatians along the middle Danube.

Constantius spent much of the rest of 353 and early 354 on campaign against the Alamanni on the Danube frontier.

Constantius had already spent part of early 361 unsuccessfully attempting to re-take the fortress of Ad Tigris.

Constantius spent the next two years neutralising the threat of the Franks who were the allies of Allectus, as northern Gaul remained under the control of the British usurper until at least 295.

His efforts were not at first successful, for at the synod of Biterrae ( Béziers ), summoned in 356 by the Emperor Constantius with the professed purpose of settling the longstanding disputes, Hilary was, by an imperial rescript, banished with Rhodanus of Toulouse to Phrygia, where he spent nearly four years in exile.

After electing Magnus Decentius ( probably his brother ) to Caesar and gathering as many troops as possible, the armies of Magnentius and Constantius met in the Battle of Mursa Major in 351 ; Magnentius led his troops into battle, while Constantius spent the day of battle praying in a nearby church.

Nevertheless, over the next three years the Rhine frontier continued to occupy Constantius ’ s attention.

A few days later, Julian was married to Helena, the last surviving sister of Constantius.

Constantius remained in Britannia for a few months, replaced most of Allectus ’ officers, and the British provinces were probably at this time subdivided along the lines of Diocletian ’ s other administrative reforms of the Empire.

Second exile: under Emperor Constantius, for 7. 5 years Apr 339 – 21 Oct 346 ; lived at Rome.

Third exile: under Emperor Constantius, for 6 years Feb 356 – 21 Feb 362 ; in the Egyptian desert.

In 351, as a consequence of the difficulty of managing the entire empire alone, Constantius elevated his cousin Constantius Gallus, the eldest surviving son of Constantius ' half-uncle, Julius Constantius, to the subordinate rank of Caesar, but had him executed three years later after receiving scathing reports of his cousin's violent and corrupt nature.

The relative moderation of Constantius ' actions toward paganism is reflected by the fact that it was not until over 20 years after Constantius ' death, during the reign of Gratian, that any pagan senators protested their religion's treatment.

The province's defences had been rebuilt in the preceding years, and although his health was poor Constantius wished to penetrate into enemy territory.

When Valentinian was less than two years old, Honorius appointed Constantius co-emperor, a dignity he would hold until his death seven months later.

From this time forward down to the latest period of the empire, for nearly a thousand years, the name occurs more or less frequently in the Fasti, and it was borne by the emperors Maximinus, Maximianus, Maxentius, Diocletian, Constantius, Constantine the Great and others.

Honorius was unable to control his own court and the death of Constantius initiated more than ten years of instability.

By means of comparison, a Briton Germanus is recorded as having met seventeen years earlier, in 429, is described by Constantius as being of tribunician rank.

St. Jerome tells us that his credit with Constantius II was so great during all these years that when Pope Liberius was deposed and driven into exile in 357, Acacius was able to secure Antipope Felix in his place.

Diocletian and Maximian seem to have understood this when they set up Constantius Chlorus and Galerius as Caesars in Gaul and Illyria respectively some thirty-five years later.

This new state of affairs was unacceptable to Constantius, who felt that as the only surviving son of Constantine the Great, the position of emperor was his alone.

His first recorded act was, after a synod had been held at Rome, to write to Emperor Constantius II, then in quarters at Arles ( 353 – 354 ), asking that a council might be called at Aquileia with reference to the affairs of Athanasius of Alexandria, but his messenger Vincentius of Capua was compelled by the emperor at a conciliabulum held in Arles to subscribe against his will to a condemnation of the orthodox patriarch of Alexandria.

In 355 Constantius became the sole Emperor and extended his pro-Arian policy toward the western provinces, frequently using force to push through his creed, even exiling Pope Liberius and installing Antipope Felix II.

He came from Antioch and served under Constantius II and was probably appointed to ensure that nobody with western associations was serving in Britain during a time of mistrust, rebellion and suppression symbolised by the brutal acts of the imperial notary Paulus Catena.

In 340, Constantius ' brothers clashed over the western provinces of the empire.

A member of the Constantinian dynasty, he was made Caesar over the western provinces, by Constantius II in 355, where he campaigned successfully against the Alamanni and Franks.

* Augusta Treverorum ( modern Trier, in Germany ) was the capital of Constantius Chlorus, the western Caesar, near the strategic Rhine border, it had been the capital of Gallic emperor Tetricus I ; this quarter became the prefecture Galliae.

He takes command of the western provinces and marries Constantius ' sister, Helena.

* First Council of Constantinople: Emperor Constantius II requested a church council, at Constantinople, both the eastern and western bishops attend the meeting.

Although Constantine was the son of the western emperor Constantius, the Tetrarchic ideology did not necessarily provide for hereditary succession.

Of the four Tetrarchs, Constantius made the least effort to implement the decrees of the edicts in the western provinces that were under his direct authority, limiting himself to knocking down a handful of churches.

Constantius, notionally the senior emperor, ruled the western provinces, while Galerius took the eastern provinces.

Valentinian was born in the western capital of Ravenna, the only son of Galla Placidia and Flavius Constantius.

This situation continued until 293, when Constantius Chlorus, now the western Caesar, marched into Gaul and reclaimed it for the empire.

In 293 Carausius was isolated when the western Caesar, Constantius Chlorus, retook some of his Gallic territories, particularly the crucial port of Bononia ( modern Boulogne ), and defeated his Frankish allies in Batavia.

So in 411 Constantius, the magister militium ( master of military ) of the western emperor, Flavius Augustus Honorius, with Gothic auxiliaries under Ulfilas, crushed the Gallic rebellion with a siege of Arles.

He thus served as deputy-emperor to Constantius I ( Constantius Chlorus ), Augustus of the western half of empire.

From 285 to 395, Augusta Treverorum was one of the residences of the western Roman Emperor, including Maximian, Constantine the Great, Constantius II, Valentinian I, Magnus Maximus, and Theodosius I ; from 318 to 407, it served as the seat of the praetorian prefecture of Gaul.

In 296 he assisted the western Caesar Constantius Chlorus in re-establishing Roman rule in Britain following the illegal rules of Carausius and Allectus.

Although Constantius rebuilt the western field army to some extent – the Notitia Dignitatum gives a list of the units of the western field army at this time – he did so only by replacing half of its units ( vanished in the wars since 395 ) by re-graded barbarians, and by garrison troops removed from the frontier.

Given the circumstances at the time Constantius may well have divided the military command of Britannia Superior in two with an eastern province named Britannia Caesariensis and a western one named Britannia Prima.

This division would have been later reorganised by splitting Britannia Caesariensis into north and south regions, named respectively Flavia after Constantius and Maxima after the western Augustus, Marcus Aurelius Valerius Maximianus.

Given the circumstances at the time Constantius may well have divided the military command of Britannia Superior in two with an eastern province named Britannia Caesariensis and a western one named Britannia Prima.

This division would have been later reorganised by splitting Britannia Caesariensis into north and south regions named after Constantius and the western Augustus, Marcus Aurelius Valerius Maximianus This would require the split to have taken place prior to Maximian's abdication in 305.