The third century was a time of civil war and decay in the Western Roman Empire. A succession of usurpers and tyrants, twenty-seven of them in a space of fifty years, only one of whom died peacefully, left the Empire crippled and vulnerable. Britain, isolated in the breakaway Gallic Empire since AD 260 under the pretenders Postumus, Victorinus and Tetricus, had been protected from the worst of the wars, but was brought back under Imperial control in 273 by the Emperor Aurelian. The country suffered constant political turmoil, with a major coup being suppressed in 276-7, until a new event again shook Britain to its roots.
The general Carausius was a thieving tyrant who, in the troubled spirit of the times, was sentenced to death by his superior, Maximian, co-Emperor with Diocletion, in 286. Carausius's reaction was the same as many others before him: he declared himself Emperor of Britain.
Carausius, for all his faults, was a genius of propaganda. Well aware of the tenuous nature of his rule, he set about portraying himself not as yet another power-mad despot, but, as his coin issues bear testament, the 'longed-for and awaited one', the 'Restorer of Britain' (Restitutor Britanniae), even the half-personified 'spirit' of the island (Genius Britanniae). Two of his coin mints alluded to Virgil's Fourth Eclogue:
After winning several battles against Maximian on the Continent by 289, Carausius portrayed himself, and, temporarily at least, was accepted as, a legitimate co-ruler alongside Maximian and Diocletian. He probably encouraged economic unity with the rest of the Roman world and, for a time, Britain enjoyed a period of peace.
The Coming of Constantius: AD 293
It was not to last. The Roman Empire was at this time ruled by a 'tetrarchy': two senior Emperors (Augusti), Maximian and Diocletian, governed East and West independently, and each had a 'junior Emperor' or Caesar. In 293 Constantius, Maximian's Caesar, conquered the last of Carausius's territories in Gaul and fragmented his fleet. Meanwhile Carausius was assassinated by one of his deputies, Allectus, who assumed command.
Allectus was not a gifted general. Constantius's forces invaded Britain three years later, defeating Allectus's army of hired German barbarians and saving London from the wrath of the survivors. A medallion found in Gaul records this event, with the grateful inhabitants of London kneeling before a mounted Constantius, along with the inscription:
In 305, after a serious illness, Diocletian retired as Augustus of the East, requiring his Western counterpart Maximian to retire at the same time. Diocletian was suceeded by his deputy, Galerius, and Maximian by Constantius. Galerius cunningly put his nephew, Maximian Daia, in the postition of Eastern Caesar, and managed to have a personal friend, Flavius Valerius Severus, appointed as Constantius's own Caesar in the West; furthermore, he had Constantius's son, Constantine, brought to the Eastern court as a hostage for good behaviour.
Constantius, however, persuaded Galerius to release Constantine
from the East, and in 306 took him on campaign to Britain.
Constantius took war to the northern frontier of Britain but
during the campaign died at York. In the tradition of
Britain, and spurred on by the ambitious German general
Crocus, who had served under Constantius, his army
proclaimed his son, Constantine, the righteous
successor to the Imperial throne.
The Ascension of Constantine I: AD 306
Galerius and Flavius Valerius Severus, who, by rights, was the legal successor to Constantius, were understandably unhappy about this arrangement. Constantine, however, was able to have himself recognised as the official deputy of Severus, although it is probable that Severus had very little control over Constantine's forces in Britain at this time.
In any case, civil wars and disputes ensued for the next eighteen years, until Constantine won the final victory in AD 324, executing his brother-in-law Licinius. In AD 312 he defeated the praetorian faction, led by Maximian's son, Maxentius, at the battle of Milvian Bridge, under the Sign of the Cross. This point marks the official conversion of Rome to Christianity, as well as the dissolvement of the ancient praetorian guard themselves.
An Empire Re-divided: AD 337
Constantine fell ill in April 337, and died the following month, only a few weeks after being baptised (it not being uncommon for Christians to put off baptism until late in life). In September of the same year, his three sons became joint emperors.
Constans, the youngest of the brothers, became emperor of Italy, Africa, Illyricum, Macedonia, and Achaea. The middle brother, Constantius II, ruled the rest of the East, while the eldest, Constantine II, ruled Britain, Gaul and Spain.
Whether it was because of known religious differences - Constantine was a Trinitarian, Constantius a follower of the Orthodox faith, and Constans an Arian - or because the three had other reasons for squabbling, it was not long before bitterness broke into open conflict. In 340 Britain's emperor, Constantine II, invaded Constans' realm but was defeated near Aquileia, the Western territories thus falling into Constans' hands.
On the Continent, Constans fought and defeated the
Franci in 341 and 342, and is known to have visited
Britain during the winter of 343. The fact that he chose
this difficult time of year to visit Britain implies that
the journey was of considerable importance. It could be
that the intention was to suppress still extent supporters
of his late brother, or that there was some military
trouble on the northern frontier. Although a largely successful ruler and an enthusiastic
Christian, Constans was also corrupt, abusing his
position to increase personal wealth and allowing the
suppression of the people by his favourites.
All did not remain quiet in the West; in January 351, Magnentius, an ambitious army general of German descent, rebelled against Constans and forced him to flee to the Pyrenees, where he was captured by Magnentius's agents and murdered. By the end of February Magnentius had gained control of Britain, Gaul, Spain, Italy and northern Africa. The following winter, Magnentius declared Magnus Decentius his Caesar, and made preparations to march against the East.
The East was still ruled by Constantine I's only surviving son, Constantius II. He proclaimed his own Caesar to take care of things in the East, and readied to campaign against Magnentius. In late 351 the two rivals met at Mursa and Magnentius was roundly defeated, but escaped; in 353 his forces were finally routed, and Magnentius committed suicide after killing his family. The Empire was once again united under a single ruler.
After Britain was returned to Imperial rule, it is recorded that the government despatched an agent called Paulus Catena (a nickname, meaning 'the Chain') to deal with supporters of the pagan Magnentius who were still at large. There followed a political terror campaign as the guilty and innocent alike were hunted down and taken, accusations flew and Paulus condemned people on the slightest excuse. Britain's Vicarius, Flavius Martinus, confronted Paulus in defence of those unjustly accused. When he himself was threatened, he attacked Paulus but failed and committed suicide. Paulus continued his witchhunt, and his actions were later approved of by the Imperial government.
Julian: AD 355
Julian was Constantius's young cousin, who had been brought up in the East, protected from the bitter conflicts over succession that had blighted most of his family. His secluded upbringing had instilled in him a deep love of history, Roman traditions and the old religion, and when Constantius installed him as Caesar in the provinces of Gaul and Britain he quickly won the respect and admiration of his troops in a series of brilliant victories on the Rhine frontier.
In 360 there were some major upsets in northern Britain by the Picts and Scots, who were launching raids across the frontier in defiance of a peace agreement. Julian sent the head of his military (magister militum) across the Channel with four units of the field army. The army wintered at Londinium, preparing for a major cleansing campaign. However, things were disturbed by events on the continent. Constantius was becoming increasingly nervous at Julian's popularity and requested that he send some of his best units to the East; the army reacted by proclaiming the initially recluctant Julian emperor, and Julian, not sure that he could trust his magister militum, Lupicinus, recalled him to Gaul and had him arrested. Julian then marched to the East to confront Constantius, but his opponent died before their armies joined. Julian became the single emperor of east and west.
Upon his establishment as sole ruler of the Empire, Julian began his attempted revival of the ancient pagan traditions of Rome, legalising pagan worship, abolishing the Church's privileges and taking back property that had been siezed by Constantine and his successors. But this revival did not outlive his short reign. Julian began a major offensive against the Persian and was killed in 363. This left the Empire, and in particular Britain, which had still not recovered from the train of terrible events that had plagued it since the fall of Magnentius, in a dire position.
Valentinian: AD 364
After Julian's death, a young Christian called Jovian was appointed Augustus, but died within a year. Then a committee of heads of state and the army met and elected a devoted Christian officer, Valentinian, to rule, in 364. Valentinian was a practically-minded and intelligent military man, a good man to cope with the serious barbarian invasions that happened across the Empire in 364.
But Britain, its defences undermanned and its morale in tatters, was in no state to defend itself against determined enemy attacks, especially with Valentinian concentrating his efforts on the Rhine frontier.
The Barbarica Conspiratio: AD 367
The year 367 saw one of the most serious barbarian invasions of the Empire in its history. Whether it was a fortuitous coincidence for the barbarians that they chose the right moment to attack the faltering Empire simultanaeously on several fronts, or whether there was, as the contemporary historian Ammianus Marcellinus implies, some kind of conspiracy between the barbarian peoples, is a matter for debate. Picts and Scots invaded northern Britain, aided by the bribery of araeni (Roman frontier scout patrols), and tribes of Franks and Saxons attacked the coastlines of Gaul.
In Britain, the senior military commander Fullofaudes (the dux Britanniarum) was besieged, presumeably with many of Britain's defensive troops, at an unspecified location, probably in the north; meanwhile, the commander of Britain's coastal forts, (the comes litoris Saxonici, Count of the Saxon Shore), Nectaridus, was killed. The loss of two senior generals and the generally poor state of Britain's garrison meant that the barbarian invaders were free to run amok. The provinces were plunged into chaos as independent bands of invaders and Roman deserters alike plundered and terrorised.
Valentinian sent to Britain a relief army very similar to that sent by Julian seven years before, consisting of four units of the field army, headed by the great general Theodosius. This force landed at Rutupiae (Richborough) and fought its way to London, capturing barbarian invaders and returning stolen booty to the people of the province. Theodosius set about clearing the country of barbarian bands, offering amnesty to deserters from the Roman army who would return to his banner, and by 369 he was ready to thoroughly restore the dilapidated towns and forts of Britain.
