As we know, Valentia Edenatorum is the name the Romans gave to the colony founded in 138 B.C. along the Turia River in the Spanish Levante, meaning Valor of the Edetani. However, the term valentia was commonly used in colonial foundations because it referred to military virtues, which is why it appears in other locations as well.
One of the last times it was used was in 369 A.D., to name a new province in Britain after a year of chaos caused by a general insurrection that united many of the native tribes against Roman rule; this event is known as the Great Conspiracy.
The main source of information about these events is Rerum gestarum libri XXXI (usually shortened to Histories) by Ammianus Marcellinus, who reports that it all began in the winter of 367 A.D., during the reign of Emperor Valentinian I, who had been in power for three years. Valentinian was a guard officer, first under Julian the Apostate and then under Jovian, whose military skills led him to rise in rank until his legionnaires elevated him to the throne. He took control of the Western Empire, and his brother Valens, whom he appointed, took control of the Eastern Empire.

Valentinian’s reign was challenging, as he had to suppress Procopius’s revolt, a relative of Julian, and face wars against various barbarian tribes. Among them were the Alamanni, Germanic people who had moved west until they settled in what are now Austria, Switzerland, and the Alsace region.
In 365, the emperor himself marched there to stop them, and although his campaign was victorious, the casualties made him reconsider his strategy in favor of negotiation. During this time, in 367, the Roman garrison assigned to watch Hadrian’s Wall rebelled.
The mutiny was likely due to a combination of factors, but there was widespread discontent among the troops and many Roman-British citizens due to delayed pay and the harsh purges fifteen years earlier by the imperial delegate Paulus Catena in an obsessive pursuit of the last supporters of the failed usurper Magnentius, who had taken refuge in Britain.

Adding to the turmoil, a severe illness soon brought Valentinian to the brink of death, sparking a succession struggle between the comes domesticorum Severus and the magister memoriae Rusticus Julianus (the emperor recovered and named his son Gratian co-Augustus).
As a result, soldiers abandoned their posts, likely astonishing the Picts, the Celtic people descended from the Caledonians living beyond the limes, who took the opportunity to resume their traditional raids south. This time, it was not just a simple raid, as their movement intentionally coincided with attacks from other barbarian groups, both insular and continental, initiating what has gone down in history as the Barbarica conspiratio.
These attackers included the Scoti from Hibernia (Ireland), the Attacotti (also Irish), and the Saxons from Germania. They landed in Britain in successive waves, coordinated in such a way that a prior agreement between them was evident; this was further highlighted by the fact that the Franks, along with another group of Saxons, did the same in northern Gaul. The midwestern and southeastern borders of the island quickly fell into their hands, and one by one, they took control of all Roman forts and bastions.

With no ability to react and defend themselves, cities suffered looting and destruction, with Roman-British citizens either killed or enslaved. In that chaos, even Nectarius, the comes litoris Saxonici per Britanniam (military commander of the Saxon coast of the Roman Empire, including the diocese of Britain), and Fullofaudes, the dux Britanniarum (military commander of Britain), lost their lives, though it’s unclear whether Fullofaudes was killed or captured.
Why was no one able to prevent this disaster? Because the miles areani (or arcani), natives who served as spies for the Romans for money to keep such situations under control, had been bribed with the promise of great loot, as Ammianus Marcellinus explains. The result was a Britain in flames, engulfed in chaos, with legionnaires deserting and slaves escaping; both groups, with nowhere to go, ended up wandering aimlessly, turning to banditry to survive.
Thus, there was no way to solve the problem with local troops. The emperor also had limited options, as he was preoccupied with the Alamanni. His first step was to send Severus, his comes domesticorum (head of the Protectores domestici, the bodyguard), who considered many troops necessary and was soon replaced by Flavius Jovinus, the magister equitum per Gallias (chief of the imperial cavalry in Gaul), a trusted man because during the reign of Jovian, he had declined the legions’ offer to proclaim him emperor.

Jovinus also seemed reliable on the battlefield, having directed the victory against the Alamanni at Scarpona and Catelauni, forcing them back to the right bank of the Rhine. Valentinian rewarded him with the consulship in 367, the same year he sent him to resolve the Great Conspiracy. First, Jovinus secured the continental area, regaining control of the coast to allow reinforcements to be sent to Britain without fear. Once achieved, Valentinian recalled him to continue the Alamanni campaign.
The second part of the plan, now to be carried out on the island, was entrusted to another general: the Spaniard Flavius Theodosius. Possibly a descendant of the gens Julia and married to Thermantia, with whom he had a son who would become one of the most famous emperors, Flavius Theodosius (better known as Theodosius I, the last to permanently rule the united empire and nicknamed the Great to differentiate him from his father, nicknamed the Elder), his appointment as comes could be considered risky, as it was his first time commanding.
Theodosius embarked at Bononia (Boulogne-sur-Mer) accompanied by his namesake son and probably the later usurper Magnus Maximus. They brought four legions of veteran Germanic soldiers (Batavians, Heruli, Jovii, and Victores) and landed at Rutupiae (or Portus Ritupis, near Sandwich, in Kent), the same place where Claudius’s conquest expedition had landed in 43 A.D. The army moved from there to Londinium (London), ready to start operations.

The first thing Theodosius did was amnesty the deserters, assigning them back to their abandoned garrisons, and dissolve the areani corps, as they could no longer be trusted. Then he set out to reconquer, although in reality, the barbarians did not control Britain; they hadn’t capitalized on their initial success, perhaps because it wasn’t in their plans, and they merely went from place to place looting. Therefore, the campaign was relatively straightforward. Ammianus Marcellinus summarizes it as follows:
“There [in Londinium], he divided his troops into many parts and attacked the enemy marauding bands, who were scattered and burdened with heavy loads; quickly defeating those who carried prisoners and livestock, he seized the loot that the miserable tributaries had lost. And when all this was returned to them, except for a small portion assigned to the tired soldiers, he entered the city, which had previously been plunged into the greatest difficulties but had been restored more quickly than expected, rejoicing and celebrating an ovation.”
By the end of the year, the barbarians had been expelled, and the soldiers who did not return to the ranks were captured and executed. Their leader was Valentinus, a Pannonian brother-in-law of the Praetorian Prefect Maximinus, who had been sent to Britain to keep him away from Rome due to some uncertain crime. It’s unclear if Valentinus was part of the Great Conspiracy, but he took advantage of the anarchy to rally the discontented and oppose Theodosius, which led to his execution; albeit discreetly to avoid possible riots.

Hadrian’s Wall resumed its role as a limes with the collaboration of friendly tribes like the Votadini to assist in its defense and surveillance. Additionally, Theodosius carried out an administrative reorganization by dividing northern Britain into two provinces: a newly created, more northern one called Valentia in honor of the emperor, and a southern one, Britannia Secunda. He also appointed a dux Britanniarum, Dulcitius, likely one of his aides, while a man named Civilis was given the role of vicar (a sort of civil governor).
The poet Claudian suggests that punitive naval landings were carried out against the Picts, while the Notitia Dignitatum (a document from the imperial chancellery) notes that many Attacotti entered Roman service, forming four units that were deployed to the continent. In sum, the Barbarica conspiratio was brilliantly suppressed, allowing Theodosius to return to Rome as a hero and replace Jovinus in Gaul as magister equitum praesentalis.
In his new and privileged position, Theodosius became the armed enforcer of Valentinian’s brutal policies, but the emperor’s death in 375 A.D. from a stroke changed everything. For some obscure reason, probably his involvement in one of the power struggles, Theodosius fell out of favor and was executed. However, as previously mentioned, after the death of Emperor Valens at the Battle of Adrianople, his son was elevated by the new emperor, Gratian, to the rank of Augustus for the East, and upon Gratian’s death, he took the throne, rehabilitating his father’s memory. It was 379 A.D., and Roman presence in Britain was to end within less than a century.
This article was first published on our Spanish Edition on July 5, 2024: La Gran Conspiración, el ataque coordinado de varios pueblos bárbaros a los romanos de Britania y el norte de la Galia
SOURCES
Amiano Marcelino, Historia
Adrian Goldsworthy, La caída del Imperio Romano. El ocaso de Occidente
Rupert Jackson, The Roman occupation of Britain and its legacy
Henry Freeman, Britannia. A history of Roman Britain
Ian Hughs, Imperial Brothers.Valentinian, Valens and the Disaster at Adrianople
Wikipedia, Gran Conspiración
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