The Roman province of Britannia had been dominated by two unique facts during its entire existence – the presence of a large deposit of tin in Cornwall and the English Channel. Tin, a difficult metal to find in large quantities and a necessary element in Roman iron, had originally made the entire island an appealing conquest and continued to make it one of the most desirable provinces in the empire until the end of the fourth century.

The narrow gap of twenty-some miles that was the English Channel, on the other hand, was nothing but trouble. Back in the first century B.C.E., the channel had kept Julius Caesar from conquering it along with Gaul. During Britannia’s entire career as a Roman province, it created nothing but problems for the Roman military. In Europe, Africa, and Asia Roman roads allowed for quick and precise tactical movements that no invader could match. Even sending soldiers across the Mediterranean was no great risk since the last pirates had been killed in Julius Caesar’s time. The English Channel was something different, though. It was not bounded on every side by Roman provinces, making it easier to access from outside the empire and because of that more open to attack.

From the beginning the channel had been one of the most vulnerable parts of the Roman Empire. During the chaos of the fourth and fifth centuries that shortcoming was exposed when Germanic tribes settled along the coasts just above the Roman Empire and learned seamanship so that they could prey on the British shipping lanes.

Their attacks made perfect sense. On land, the Roman army was unparalleled and the boundaries of the empire carefully and consistently guarded. On the sea the situation was different. Water meant none of the natural obstacles that made guarding easier; as a result pirates could attack anywhere. Add to that that the Romans were not natural seamen. It was only natural that the Germanic invaders would exploit the weakness.

In response, the British governors did something that was common in the Late Roman Empire. They hired Germanic tribes to protect their shipping lanes. In exchange for food, supplies and steady pay and under the official direction of a Roman unit, a chieftain agreed to patrol one section of the English Channel. His entire tribe – men, women, and children – would immigrate to a “hot spot” along the southern or western coast of Britain. From there, he and his warriors would protect the shipping lanes from piracy. During the course of the fourth century, several tribes were hired as foederati and stationed along the northern and southern coasts of Britain. It seems to have worked because information and Romano-British goods continued to flow into Europe, while coins to flow into Britain.

The foederati system was not an indicator of weakening Roman power it was simply another example of Roman adapation; in this instance a new technique to adjust to the threat posed by aggressive Germanic tribes. Under the foederati system, Germanic peoples settled along the Roman Empire’s boundaries, supervised by Roman officers and supported by Roman troops.

They were also immersed in Roman culture; the Roman officers they interacted with spoke only Latin, as did any nearby villagers they might trade with. The nearest Germanic tribes might be several miles further away and the Romans made certain there was no need to contact them for food or supplies. In a scenario like that, the first generation of migrants might keep their language as the primary communication, but their children were bilingual and by the third generation Latin was the main language and Germanic something that was spoken only at home. When it emerged in the third century, the foederati system was an effective means of Romanizing the Germanic tribes.

However, over the next two hundred years the Roman Empire declined. Internally, dynasties became shorter and less stable; as the fourth century wore on it became uncommon for an emperor to pass on his title. Externally, Roman borders were tested in Europe and Asia by dozens of tribes and kingdoms. Roman Britain’s threats were Irish raids along its western coast, Pictish and northern Briton attacks across the northern border, and of course Germanic pirating along the English Channel. All of these changes weakened Rome’s economy and the strength of its culture. Its weakening culture, along with less direct control over the foederati caused by Roman units regularly moving across the empire to defend its borders, made Romanization of the Germanic tribes less effective.

In the year 367, Ammianus Marcellinus recorded an alliance between the Picts, Irish and Germanic tribes in a joint attack on the province. The assault overwhelmed Roman defenses, exposing their inadequate numbers by attacking simultaneously from the west, north, and east. Unlike previous attacks, the allies took what they wanted and withdrew immediately so that Roman units could not meet the threats one at a time. Ammianus tells us that the villages of Roman Britain burned to the ground.

In response, the emperor promoted Theodosius the Elder to comes, or general, and sent him to Britain in 368. Theodosius probably realized there were not enough Roman troops to protect the entire province. There is a good chance that he transferred most of the northern and western garrisons to reinforce the southeastern coast while he established buffer kingdoms in northern England and Wales. Once he had reestablished Roman order and ensured the tin supply was protected, he returned to the continent. The emperor rewarded him with the title of Comes Britanniarum.

Theodosius had countered the attacks but had done nothing to change the circumstances which had led up to them. As a result, the Picts and northern Britons continued to raid below Hadrian’s Wall, never conquering the area for reasons that will be developed below but never slowing their attacks either.

The Irish, their younger princes driven by the ithagenic or cousinly succession of their culture, would continue raiding the western coast. Portions of Cornwall, southern Wales, and the island of Anglesey would be under their control before 400. They would establish kingdoms in the next few decades that would last for up to a century. Other Irish groups, likely raiders of British, Pictish, and Irish settlements alike, would move into Argyll and probably used the unique geography of the area to hide from their victims. Its pirating groups would eventually develop into the kingdom of Dalriada, which would in turn become the core for Scotland.

However, as Theodosius had hoped, his alterations to Britain’s defenses allowed Roman Britain to survive. Because of his efforts, Cornwall continued producing tin and transporting it to the continent.

In 383, the Irish, Picts, and Germanic tribes came together again and overwhelmed the province of Britannia with a second joint attack. This time Rome sent Magnus Maximus to restore order. Roman records say that he defeated all the attackers quickly and effectively. Welsh oral and genealogical memory credits him with founding several dynasties. This could mean that he installed kingdoms in Wales and Cornwall to act as buffers against future attacks. More likely, his successes in battle touched a nerve with the British and they remembered him as a great hero.

Having restored order to the province, his legions proclaimed him the new emperor. An intelligent man, Maximus either found a new and loyal Britannia governor or satisfied himself that the old one was loyal. He then drained the northern and western frontiers of legionnaires and probably took units from the Saxon Shore command before sailing to the continent to fight his way to Rome. If he had managed it, Britannia would have remained an integral part of the empire. But Maximus was killed in 388. Just as bad, his soldiers never returned to the island. Rome had suffered a devastating loss in 387 at the Battle of Adrianople, so his troops were likely absorbed by the victor’s army to help recoup some of the losses.

In Britannia the loss was not just military but political and economical; it effectively left the province with a governor loyal to a dead traitor and no currency to pay either government employees or the few soldiers who remained. It was a dangerous situation in the face of Germanic, Irish, and Pictish attacks and with the foederati as loyal to the Roman culture as they were to their pay, so the Romano-Britons must have deposed their Maximian governor and all of the people he had appointed – most of the bureaucracy and any regional officials – before begging Rome to accept the province back into the empire. To their relief, Rome accepted Britannia and a governor was sent to them along with additional Roman troops. In 388 Britannia probably had fewer soldiers on the island than before Maximus, but at least there was enough to maintain order and man the necessary fortifications.

There were not enough, though, to to protect the borders from raiders. Soon the province was being attacked again on all sides again. The only real difference now was that the three groups did not need to work in tandem any more to take what they wanted.

As soldiers and officers were in short supply, there were probably fewer posted to the foederati than before which would have meant less control over them. The Germanic tribesmen must have noticed the change. They could not have missed the fact that raids were becoming more frequent either. All this meant that they were being assimilated into Roman culture more slowly, if at all.

Even with Britannia’s reintegration back into the Roman Empire, the increasing raids of the late fourth and early fifth centuries meant that shipments of gold, supplies, and pay for the soldiers were much less consistent. This must have irritated the legionnaires and the foederati, but there are no records of them complaining. Instead it was the wealthy that reacted first. Reduced trade also meant less of the Roman culture was brought to them – pottery, art, literature, wine, oil, and fashions. Letters from friends and connections with the empire’s politics only went through haphazardly. With the increased raiding, even they and their families were no longer safe if a raiding party happened upon their estate. As a result, many of the wealthiest Romano-Britons left Britannia during the late fourth and early fifth century for the comparative safety of the continent, leaving their villas abandoned and eventually replaced by much smaller farmsteads.

The departure of the upper class weakened Britannia’s economy. More importantly, it crippled the political and social structure; without the wealthy there was no group with the funds and the social expectations to repair buildings and roads. Roman Britain can be said to have begun its process of decay during this period.

It was only in the fifth century that the legionnaires finally came to realize that they were essentially isolated from the rest of the empire and rebelled themselves. Beginning in 406, the Roman Army in Britain selected three men in succession to be the emperor. The first two proved to be disappointments when they refused to leave Britannia and fight their way to Rome. The third man, Constantine, was not so squeamish. He departed for the continent in 407. More important for the island, he first installed his own governor of Britannia, and probably drained the province of most of its regular troops to swell his army.

Constantine probably planned to send soldiers back to Britannia once he was crowned in Rome. Unfortunately for the island he was killed in 411 and his soldiers were not returned to Britannia. They were needed too; the province was being overrun by 410. Desperate for help, the Romano-British went with a formula that had worked in the past. They deposed Constantine’s entire government to show their loyalty to Rome and then requested that the emperor send them a new governor and garrison.

The emperor could not though. Rome had also been sacked in 410, so when he received the letter from Britannia he was more concerned with reestablishing his authority at home than sending educated men and trained soldiers off to some far-away province. As tradition says, he told the civitates, or cities, of Britain to look to their own defense. From that point on, the Britons were on their own.

To sum up, Britain was unique in the post-Roman period for several reasons. There was no Roman-based government because the natives had overthrown Constantine’s officials in anticipation of Rome sending its own. When the empire failed to send officials, the Romano-British were left with only local governments – villages, towns, and cities.

There was no way of reestablishing an island-wide government, either. The aristocrats had been leaving for decades, which meant that no one had the money to get the government restarted. Nor could the military enforce a government or even elect its own leader; Constantine had taken all but skeleton crews from the border areas. All that might seem hard to believe, but apart from a single native source writing decades beyond living memory there is not a shred of evidence that any government beyond the civitates survived 410.

In 410, the Britons did control most of the island but had no standing military, no island-wide government and, because of decades without the aristocracy contributing resources for roads and official hospices, there were limited communications. Worse, the Germanic tribes were still raiding the southern and eastern coasts, the Irish were attacking from Argyll down to Cornwall, and the Picts were crossing into British territory at will. It was only a matter of time before the British had new masters.

1 Magnus Maximus is one of the few names that Gildas mentions and, as the author has demonstrated, Maximus’ activities occurred long before Gildas’ historical horizon; Johnson, Evidence of Arthur, (Madison, 2014), 159-60.
2 Cleary, The Ending of Roman Britain, (1989), 134; Reece, “The end of the city in Roman Britain”, The City in Late Antiquity, ed. John Rich, (London, 1992), 136-44 and “Town and country: the end of Roman Britain”, World Archaeology 12 (London, 1980), 77-92.
3 Zosimus, Zosimus. New history, trans. Ronald T. Ridley, (Canberra, 1982), 6.5.2. They rid themselves of Roman administration.
4 It has been argued by some that the historian meant that Honorius was addressing the natives in Bruttium, a region in Italy. Birley, The Roman Government of Britain, (Oxford, 2005), 461-3; Bartholomew, “Fifth-Century Facts”, Britannia 13 (Stroud, 1982), 261-70. However, no other contemporary historian claimed that Bruttium requested aid.
5 Professors Koch and Thompson agree with that assessment though they come to it by different means; Koch, Cunedda, Cynan, Cadwallon, Cynddylan: Four Welsh Poems and Britain 383-655, (Cardiff, 2013), 81; Thompson, St. Germanus of Auxerre and the end of Roman Britain, (Woodbridge, 1984), 37.