The end result was that in 340, Constantine II invaded Italy.

King Æthelstan was successful in securing Constantine's submission in 927 and 934, but the two again fought when Constantine, allied with the Strathclyde Britons and the Viking king of Dublin, invaded Æthelstan's kingdom in 937, only to be defeated at the great battle of Brunanburh.

In that year, together with Owen of Strathclyde and Olaf Guthfrithson of Dublin, Constantine invaded England.

Constantine and Thomas barely escaped, and Morea was invaded.

After the success of Constantine V's general, Michael Lachanodrakon, who foiled an Arab attack on the eastern frontiers, a huge Arab army under Harun al-Rashid invaded Anatolia in summer 782.

Constantine accepted the kingship and repelled the Huns and Picts who had invaded Britain.

Civil war erupted when Constantine refused to submit to Uroš III, who then invaded Zeta, and in the ensuing battle, Constantine was killed.

In 746, profiting by the unstable conditions in the Umayyad Caliphate which was falling apart under Marwan II, Constantine invaded Syria and captured Germanikeia ( modern Maraş, his father's birthplace ).

The last, Constantine III, raised an army from the remaining troops in Britannia, invaded Gaul and defeated forces loyal to Honorius led by Sarus.

In 340, Constantine II invaded Constans I's territory in Italia ; he was defeated and killed at Aquileia, and his provinces passed to the control of the brother whom he had attempted to displace.

In 759 Constantine V invaded Bulgaria again, but this time his army was ambushed in the mountain passes of the Stara Planina ( battle of the Rishki Pass ).

Constantine received Britannia, Gaul, Hispania, and Mauretania, while Constans, though initially under the supervision of Constantine II, received Italy, Africa, Illyricum, Pannonia, Macedonia, and Achaea.

Constantine was eventually trapped at Aquileia, where he died, leaving Constans to inherit all of his brother ’ s former territories – Hispania, Britannia and Gaul.

Constantine, proclaimed Augustus by the troops received Gaul, Britannia and Hispania.

** Marcus, Gratian, Constantine " III " and Constans " II " in Gaul and Britain ;

After Emperor Constantine ’ s reforms in AD 318, the border between Gaul and Italy ( two of the four praetorian prefectures of the Roman Empire ) was located east of Turicum, crossing the River Linth between Lake Walen and Lake Zurich, where a castle and garrison looked over Turicum ’ s safety.

* 407: Constantine III leads many of the Roman military units from Britain to Gaul, occupying Arles ( Arelate ).

* Spring – Constantine III crosses the Alps into Liguria ( Northern Italy ), but retreats to Gaul after Gerontius revolts in Spain against his son Constans II.

* The Roman usurper Constantine III established his headquarters at Arles ( Southern Gaul ) and elevates his eldest son, Constans, to the rank of Caesar.

Constantine occupies Arles and established tenuous authority over Gaul, sharing control with marauding " barbarians ".

* Emperor Honorius sends two Roman generals to deal with the usurper Constantine III in Gaul.

* Summer – Constantine I joins his father in Gaul, from Bononia ( Boulogne ) they cross the Channel to Britain and make their way to Eboracum ( York ), capital of Britannia Secunda and home to a large military base in order to deal with a rebellion by the Picts.

* November 11 – The Congress of Carnuntum: Attempting to keep peace within the Roman Empire, the leaders of the Tetrarchy declare Maxentius a public enemy and Licinius is proclaimed Augustus, while rival contender Constantine I is declared Caesar of Britain and Gaul.

Constantine, disappointed in his hopes to become a Caesar, fled the court of Galerius after Constantius had asked Galerius to release his son as Constantius was ill. Constantine joined his father's court at the coast of Gaul, just as he was preparing to campaign in Britain.

Beginning in 307 already, he tried to arrange friendly contacts with Constantine, and in the summer of that year, Maximian traveled to Gaul, where Constantine married his daughter Fausta and was in turn appointed Augustus by the senior emperor.

The destruction that occurred in Gaul and the lack of an effective response from the court in Ravenna lent support to the rebellion of Constantine III in Britain, which Stilicho proved unable to deal with.

As Constantine moved his forces into Gaul, Stilicho sent his subordinate Sarus to deal with him.

Constantine III initially rebelled against Honorius and took further troops to Gaul, but was later recognised as a joint emperor.

Sidonius may be a descendant of another Apollinaris who was Prefect of Gaul under Constantine II between 337 and 340.

The British provinces were isolated, lacking support from the Empire, and the soldiers supported the revolts of Marcus ( 406 – 407 ), Gratian ( 407 ), and Constantine III.

The army rebelled and, after elevating two disappointing usurpers, chose a soldier, Constantine III, to become emperor in 407.

Emperor Constantine III ( Western Roman Emperor ) | Constantine III ( 407 – 411 )

Christianisation intensified with the legalization of the Christian religion under Constantine in the early 4th century and its promotion by subsequent Christian emperors, but in 407 the Empire withdrew its legions from the province to defend Italy from Visigothic attacks in which the city of Rome would be sacked in 410.

Usurper Constantine III declared himself emperor in the West ( 407 – 411 ) and made Arles his capital in 408.

Uther's family is based on some historical figures ; Constantine on the historical usurper Constantine III, a claimant to the Roman throne from 407 – 411, and Constans on his son.

Constantine had revolted against Honorius ( 407 ), but then he had broken his relationship with general Gerontius, who had proclaimed Maximus Emperor in opposition to both Honorius and Constantine ( 409 ).

* Elton, Hugh, " Constantine III ( 407 – 411 A. D .)", De Imperatoribus Romanis

Flavius Claudius Constantinus, known in English as Constantine III ( died 411 by 18 September ) was a Roman general who declared himself Western Roman Emperor in Britannia in 407 and established himself in Gaul.

At the time of this invasion, the provinces of Britain were in revolt, setting up and pulling down a series of usurpers, which ended with the elevation of Constantine early in 407.

* Constantine III ( Western Roman Emperor ), self-proclaimed western Roman Emperor 407 – 411

No further information is known after this period and scholars believe the XX legion was still stationed in Britain when the usurper Constantine III pulled the bulk of the military forces from there in the year 407 for his doomed campaign on the continent.

As Maximus himself was dead by the end of 388, and Constantine III departed from Britain with the last of Rome's military forces in 407, less than a generation later, it is doubtful that Rome had much direct influence over the military actions of the Votadini, either through Maximus or any other emissary, for any significant length of time.

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.

The usurper Constantine III had taken the last Roman troops from Britain in 407, and the civilian administration had been expelled by the natives a little later, leaving the inhabitants to fend for themselves during increasingly fraught times.