Limes Britannicus

The frontier of the Roman Empire in Britain is sometimes styled Limes Britannicus ("British Limes") by authors for the boundaries, including fortifications and defensive ramparts, that were built to protect Roman Britain (the term Limes is mainly and originally used for the Roman frontier in the Germanic provinces). These defences existed from the 1st to the 5th centuries AD and ran through the territory of present-day England, Scotland and Wales.

Britain was one of the most troubled regions in the European part of the Roman Empire and could only be secured by the Roman Army at considerable effort. Despite a rapid victory over the tribes in the south, which Claudius' field commander, Aulus Plautius, achieved in 43 AD for Rome, the resistance of the British was not completely broken for a long time afterwards. Nevertheless, the Romans succeeded in further consolidating their rule in the period that followed, although the troops stationed there were overburdened by having to defend Britain simultaneously on three fronts. The incursions of barbarians from the north of the island repeatedly caused serious problems. To the west and south, the Britannic provinces had to be defended against Hibernian and Germanic attacks. Rome held the province for three and a half centuries. Behind the protection of Hadrian's Wall and that formed by the natural coastal boundaries to the east, south and west, the region we now know as England was heavily influenced by Roman civilisation. Hadrian's Wall and the castra on the Saxon Shore are still the most prominent symbols of Roman rule over Britain.

The conquest of Britain was ordered in 43 AD by Emperor Claudius. Claudius had a low reputation among his troops and was forced - according to the tradition of emperors - to acquire glory on the battlefield in order to secure his rule permanently. Britannia had large deposits of precious metals, fertile soil and vast forests, which made it economically attractive to the Romans. Most of Great Britain was conquered in the first year of the invasion. However, this campaign sparked a long-running resistance by the native Britons against their occupiers that lasted for decades. Following the Boudica Uprising, they almost succeeded in expelling the Roman Army from the island. It may have been that Claudius initially planned to occupy only the lowland regions of Britain. In the 1st century, the Romans had no clear idea how large the island was. Roman influence was therefore continually extended as the borders of their conquered territory shifted significantly several times. Time and again fighting broke out with the indigenous Celtic tribes in the border zones of the new province, compelling Roman troops to move into new areas in the west and north, in order to ensure the permanence of Roman rule and to secure their borders. In 80 AD, the army of Agricola penetrated well into Caledonian territory (modern-day Scotland) after his victory in the Battle of Mons Graupius. After attempts to permanently occupy the Highlands failed, the Romans fell back in 120 AD to the Stanegate line. The majority of troops in Britain had to continue to be stationed in the north. As protection against raids by pirates from Ireland (Hibernia), a powerful protection force was also needed on the west coast. In particular, the regions of Cumbria and Lancashire suffered time and again from the plundering of the Irish.

Even during the reign of Hadrian, Britain was still not an entirely peaceful province. Coin missions dating to this time indicate that Britain was in a "permanent state of defence" and pre-Roman tribal societies continued to occupy the outer regions of the island. The greatest danger was always posed by the Picts from who lived on the far side of the Scottish rivers, the Forth and the Clyde. Moreover, in the lands between these rivers and Hadrian's Wall, the Central Lowlands, there were still four other Celtic tribes - the Votadini, Selgovae, Damnonii and Novantae - which Rome sought to incorporate in order to be able to neutralise their fighting power and make use of their farmland. To that end, road forts were built to protect Rome's territorial claims. From 122, the northern border was secured by Hadrian's Wall. The fortifications on the coast of Cumbria, which were erected later, were intended to prevent the Wall being circumvented in the West. Under Hadrian, the three legion camps were rebuilt in stone. In 140 AD, Roman troops advanced again against the Caledonians and built the Antonine Wall further to the north but, by 160, it had been abandoned. In the period 155-158 AD there was a revolt in Britain which led to heavy losses being inflicted on the local legions. These losses had to be made up by reinforcements from the Germanic Rhine provinces. At the end of the 2nd century seafaring Germanic peoples – the Angles, Saxons and Franks - began to threaten the Gallic and British coasts with the first raids from the continent. During the course of the civil war that followed the election of Septimius Severus as emperor, his rival, Clodius Albinus, set forth for the continent in 197 with the Britannic army, but suffered a crushing defeat against Severus’ troops in the Battle of Lugdunum (Lyon).

In the 3rd century, Roman Britain underwent profound changes. With the return of soldiers to the island, their first task was to drive back the Picts, who had taken advantage of the absence of Roman troops to raid and plunder extensively. As a result, Septimius Severus ordered a large-scale punitive expedition against the tribes north of Hadrian's Wall and even reoccupied the Antonine Wall for a short time. Unlike the other provinces, Britain appeared relatively stable and calm. The short-term separation of the island from the rest of the Empire under the usurper Carausius showed that this was an illusion and that the power of Rome was becoming increasingly weaker in Britain as well. Carausius used inter alia the anger of the Britons arising from their neglect by Rome for his own power-political purposes and founded his own empire consisting of Britain and a strip of land in northern Gaul. He wanted to build it up into his own centre of power within the Roman world, but failed in the face of a Roman counter-offensive ordered by Constantius Chlorus, which soon toppled the newly founded Romano-British Empire. In the late 3rd and into the 4th century, the security situation on the continent became critical again, as the pressure from barbarian tribes on the borders of the Rhine and Danube had not waned. From the 4th century, Britain was again increasingly the target of attacks by Saxons, Picts and Scots. The last named sailed around Hadrian's Wall and initially penetrated far into the south of the country. The crews of the watchtowers and forts on the coast of Cumbria were usually only able to warn the population. Due to the precarious security situation in the rest of the Empire, units were increasingly withdrawn from the island so that, in the end, the British provinces were almost exclusively guarded by locally raised auxilia or newly recruited Germanic mercenaries. At the end of the 4th century, the last Roman troops left their camps in Wales, with the result that raiding and settling by the Irish significantly increased there. Around 400 AD, much of Hadrian's Wall also had to be abandoned for lack of troops. Most units of the mobile field army were ordered to leave Britain in 401/402 to go to the defence of Italy against the Visigoths under Alaric.

After the invasion of Gaul by several barbarian tribes in 406, contact was broken between Britain and the Western Roman central government in Ravenna. As a result, the provincial Roman army - probably encouraged by the local nobility – elected three of their own emperors in rapid succession, of whom the commander of the army eventually succeeded in 407 in holding onto power. He wanted to take advantage of the political and military chaos in Gaul caused by the barbarian invasion to strengthen his power and crossed with his loyal troops across the English Channel. At this point, the Romano-British renounced him probably in the wake of an uprising against the governor appointed by him. Around 410 AD, the last units of the mobile field army left the island, drawing to a close 300 years of Roman rule over Britain.

Thereafter, Anglo-Saxons were apparently recruited from the continent by the Romano-British civitas as reinforcements in order that they might defend themselves more effectively against the constant attacks. While some researchers assess that some of them had already reached the shores of Britain by 380 as mercenaries, the majority of historians believe this first took place in 440. However, these mercenaries soon rose up against their masters, allegedly because they were not adequately supplied by them. Their leaders now established their own independent kingdoms which expanded rapidly to the west and north. Many regions of Britain continued to be governed by the Roman model even after the Romans left, but this practice soon ceased with the continuous encroachment of Anglo-Saxon renegades. With the collapse of the old administrative districts into independent small kingdoms, the jointly maintained provincial army also lost its Roman character.

Four years after the Roman invasion, the conquered territory extended roughly as far as a line from Exeter (Isca Dumnoniorum) to Lincoln (Lindum Colonia), an important intra-Britannic transport hub. Around 55 AD the main camp of the Legio II Augusta was established in Isca Dumnoniorum. This was abandoned about 75 AD and the place was elevated into the civitas of the Dumnonii. The city of Lincoln was initially the headquarters of the Legio IX Hispana and, at the end of the reign of Domitian, was elevated to a Colonia. It lay on the river Witham, another important communication route. Near the town there was probably a bridge across the river. "Ermine Street" linked London (Londinium) with the legion camp of York (Eburacum). In addition, one of Roman Britain's main roads, the "Fosse Way", which ran from the west from the Welsh legion base of Exeter, terminated in Lincoln. Furthermore, a road led from Lincoln eastwards to the shores of the English Channel.