When and Why Did Roman Britain End?

The Roman provinces of Britannia were the first to fall away from the empire in the early 5th century, as the Western empire entered into its final stage of decline and collapse. Although the provisional date of 410 CE is offered by Zosimus as the year of severance between the island and the continent, Roman authority in Britain had long been on the wane. Adversely, the decades following 410 CE saw a continuation of Roman lifestyles and culture in Roman Britain also.

At its apex in the early 3rd century, the Roman Empire spanned three continents. It reached as far north as the Grampian mountains in Scotland and as far south as the Upper Nile in Egypt. Roman citizens were found in, what is today, the Ukraine, Morocco, Austria, Syria, Germany and many more nations. It was not the first multi-ethnic and multicultural superstate, but its impact on the course of western history is yet to be matched.

Rome’s meteoric rise to empire can be traced back to its victories in the Punic Wars (264-146 BCE), following which its dominion became apparent over all Italy, North Africa, Spain, most of modern Greece and parts of Anatolia. The following centuries saw Rome’s influence continue to grow throughout the Mediterranean and increasingly into the Celtic world. The Proconsul, Julius Caesar, created pretexts to launch his Gallic Wars (58-50 BCE) into modern France and Germany, which also brought him into contact with the peoples of Britain (55 & 54 BCE). However, it was not until a century later (43 CE) that Britain was added to the provincial collection of the Roman emperors, and it was not fully subdued for another 40 years. There it sat, relatively obediently, on the most north-westerly corner of classical civilization for a further three centuries.

The Society, Administration and Army of Roman Britain

From these urban islands, civilization was diffused throughout a province in the form of Roman jurisprudence, the Latin tongue, patronage and benefaction, and the allures of city living; bath houses, theatres, forums and the like. In return the natives surrendered their own cultures and a portion of their livelihoods which funded the Roman military machine. Tax income across the empire contributed a very small proportion of imperial revenue, a larger percentage came from the state-owned precious metal mines. Tacitus notes that “Britain produces gold and silver and other metals: conquest is worthwhile” (XII.6). However, the garrisoning needs of the island, which were significant, meant Britain required a larger legionary presence (and expenditure) than any other single province.

Initially Britannia was designated a singular province, receiving the standard administrative staff required, such as a governor. Either in the late 2nd or early 3rd century, under the Severan emperors, the province was divided into two, Britannia inferior and superior, perhaps signifying the increasing complexities of governing an increasingly “Romanized” province.

Under the bureaucratic reforms of Diocletian the island was subdivided into four provinces under the overall diocese of Britain which was itself part of the greater praetorian prefecture of Gaul. Each of these smaller provinces had their own capitals, demonstrating the success of the model Roman city in Britain. Towns such as Londinium (London), Eboracum (York), Lindum (Lincoln), Luguvalium (Carlisle), Corinium (Cirencester) and Verulamium (St. Albans), though not as populous and vibrant as their Mediterranean counterparts, show that Britain was firmly part of the Roman world. A mysterious fifth province, Valentia, may also have been added under the Valentinianic emperors, though its boundaries remain the subject of speculation.

Throughout its history as part of the Roman empire, Britain required a large military presence. Unlike the Rhine or Danube frontier provinces, Britain was assailable from not one, but three angles. Most obviously from the Picts of Caledonia, whose raids gave cause for the famous wall built by Hadrian. As well as this hard land border, Britain was also a naval frontier. It was vulnerable to raids from both the Celtic Hibernian (Irish) tribes such as the Scots to the west and from Germanic tribes such as the Saxons to the east.

In an attempt to mitigate the latter, a series of coastal fortifications were constructed in the late 3rd century along the southeastern coastlines of Britain, now known as the Saxon Shore forts. These threats, compounded by the potential for a revolt of the native Britons meant that a higher-than-average three legions were stationed in Britain for most of its provincial history. Compare this to the one legion stationed in Spain, an area twice as large.

Choosing a year or event from which to begin the decline of Roman Britain could prove difficult as its fortunes rose and fell roughly in line with the wider empire. The legions of Britain were defeated at the Battle of Lugdunum (197 CE), while fighting for their erstwhile governor turned imperial claimant in a civil war. Septimius Severus emerged victorious from the contest and made sure to campaign in Britain to secure the loyalty and respect of its legions, his former adversaries.

Following the decline of the Severan Dynasty, the empire entered a prolonged period of civil unrest and military conflict known as the crisis of the third century. During this period, Britain seceded from Roman control, firstly under the so-called Gallic Empire in the 260s CE. This state emerged in the provinces east of the Rhine after the Italian administration proved unable to defend that area. Then, following its reacquisition by Aurelian, Britain seceded again as its own entity under the wily general Carausius in the 280s CE.

This Britannic Empire, which held parts of northern Gaul, eluded the machinations of the western Augustus, Maximian, and was finally reintegrated under the Caesar Constantius. During the complex reorganization of the Diocletianic tetrarchy, the Britannic legions again threw their weight into the political arena by declaring the son of Constantius (Constantine) as the new western Augustus (306 CE). Over the next 20 years, Constantine would come to unite the entire empire under his sole rule. One of his sons, Constans, made an unannounced visit to Britain in the 340s CE, perhaps to survey his new, and by now notoriously troublesome, province. Other emperors had cause for concern over Britain, with Valentinian sending Count Theodosius there to suppress a great barbarian conspiracy on the island in 367 CE.

Throughout the 4th century, the archaeological record of the towns of Roman Britain show a steep urban decline, while activities at villas and estates appear to increase. For example, in Londinium, the supposed capital, roads fall into disrepair and the port and forum basilica were seemingly destroyed for building materials either in the late 3rd or early 4th centuries.

Meanwhile, in Eboracum (York) occupation seems to have retreated to a fortified urban core while the peripheries were abandoned, reducing the commercial and industrial activity of the city substantially. Some towns managed to buck this trend briefly. Corinium (Cirencester) played host to an economic and trading boom in the late 4th century, but by the turn of the 5th most of its townhouses had been abandoned. In Luguvalium (Carlisle) the urban periphery was maintained into the early 5th century, likely due to the safety afforded by the proximity of the frontier garrisons but it also succumbed to abandonment not long after.

Overall, the general trend of the towns of Roman Britain in the 4th century is one of urban decay, with most towns seeing piecemeal fortifications designed to protect an urban core. This is crucial to dating the end of Roman Britain because, as we have discussed above, the towns were the focal points in the network of Roman civilization.

Ammianus Marcellinus (Book 28.3) describes how Count Theodosius refortified the towns and forts of Britain in the late 360s CE and this is mirrored in the archaeological record as towns shrink in size but become more defensible. Walls are heightened, turrets constructed, and ramparts extended.

Essentially, normal urban life was lost forever as towns became places of refuge in times of uncertainty, much as they had been before the Roman conquests. The Britons began to return to the land. Here we see that although nominally, Britain remained a part of Roman civilization. Culturally there had been a regression away from classical Mediterranean urban lifestyles toward the more rural existence of the Celtic past.

Although Britain remained on the peripheries of the Roman world, it also remained a province with a significant military presence. However, this force was not limitless. It could therefore be used in continental powerplays, but this in turn would leave the island province defenceless or at the very least weakened. It was the result of two usurpations launched from Britannia that the island was left absent of nearly all means of defence. Following which, the whole diocese was left as a withered leaf ready to fall from the imperial branch at the slightest breeze. Yet when it came, the Picts, Scots and Saxons would come with the force of a gale.

The first usurper to spring from Britain was general Magnus Maximus. Magnus was likely the governor of Britannia Prima, the area around modern Wales and the Southwest of England. He has remained a character in Welsh folklore as a result. He seized the throne from Emperor Gratian in the west and sought legitimacy from the eastern Augustus, Theodosius, son of the Count of the same name.

Gildas notes this as the moment that “Britain is left deprived of all her soldiery and armed bands, of her cruel governors, and of the flower of her youth” and that not long after the Britons “left their cities, abandoned the protection of the wall, and dispersed themselves in flight more desperately than before.” We can therefore see this, alongside the archaeological evidence of civic decline as a period in which the British provinces were no longer safe. Absent of garrisons, the towns were further deserted. Those left coped as best they could.

Maximus soon neglected his former responsibilities in Britain in favor of continental ambitions. He was defeated by Theodosius in Italy in 388 CE with most of his forces, leaving Britain and most of northern Gaul defenseless. The Emperor Theodosius, dying in 395 CE, had been too preoccupied with further civil wars in Italy to reinforce Britain. His son and successor, Honorius, was too docile and incompetent to attempt it. However, the western Magister Militum, Flavius Stilicho, either led or sent an expedition to the island in the late 390s CE.

Stilicho was the effective ruler of the western portion of the empire between 395 and 408 CE and seems to have been one of the few men at court still in possession of martial vigor. It is also likely that repairs to Hadrian’s Wall were undertaken around the turn of the 5th century on the instruction of the Magister Militum.

If Stilicho had conducted or ordered operations in Britain, it may well have been a further draw on the islands dwindling manpower. As Gildas and Bede both allude to, trouble was brewing in Europe. Stilicho was engaged in a cold war of sorts with the eastern court and was also intermittently at odds with King Alaric and his Gothic nation. Stilicho may have intended to return the garrisons to Britannia after dealing with his continental adversaries but sadly, he was assassinated in 408 CE, the victim of court intrigue. Gildas describes that the powerful Roman, Flavius Aetius, as unable to assist them at this time, though his mention of Aetius is anachronistic and he likely meant Stilicho.

By now a barebones army defended Britannia and Gaul as most of the Roman legions were defending Italy and Illyricum. The remaining neglected towns and troops of Britain elected a rank-and-file soldier, Constantine, as their new emperor, hoping to recreate the success of 306 CE. Constantine III scraped the barrel in Britain in 407 CE before crossing over to Gaul to defeat the invading Franks, setting up a short-lived western separatist state and meeting his end.

By now Britain had nothing in the way of defense. The Scots and Picts returned in force unopposed to ravage what they could of Roman Britain. Gildas talks of repeated pleas for assistance which were left unanswered before a sort of governing council decided to employ Saxon mercenaries to defend themselves. The weak Britons would soon come to regret that decision but the story of the Saxon kingdoms is not our concern.

Zosimus in his Historia Nova (177) tells how after the revolt of Constantine, Honorius wrote to the Britons instructing them to look to their own defense. Whether this was a complete relinquishment of control of the diocese or whether it was intended to be temporary we cannot know. The account is still disputed as it could have been referencing a different part of the empire such at Bruttium or Raetia. Ultimately, after seeing Roman culture on the decline for several generations, continually being stripped of its legions and garrisons and being left undefended on the periphery of the Roman world, in 410 CE Britain slipped away from the empire forever.