3. Germanic Invasion

By tradition, it is considered that the pagan Saxons were invited as mercenaries by Vortigern, a 5th century Brython warlord to assist in fighting the Picts and Irish. It seems certain that there existed a person called Vortigern. The stories surrounding him may have been based on the facts of his life, and may also have been based on events not directly related to him. It is clear that he earned a poor reputation in later legend, where he was eventually remembered as one of the worst kings of the Britons.

In fact, archaeology has suggested some official settlement as landed mercenaries as early as the 3rd century. The new arrivals rebelled, plunging the country into a series of wars that eventually led to the Saxon occupation of Lowland Britain by 600. The pattern of barbarians hired as mercenaries turning on their former masters was repeated all over the crumbling Roman Empire at this time, so Britain was not an exception.

There were attempts to appeal to the Romans. A significant date in sub-Roman Britain is the famous Groans of the Britons, an unanswered appeal to Aëtius, leading general of the western Empire, for assistance against Saxon invasion in 446. The plea as recorded by Gildas reads:

To Agitius [Aetius], thrice consul, the groans of the Britons... the barbarians drive us to the sea, the sea drives us to the barbarians, between these two means of death we are either killed or drowned.

‘Barbarians’ refers to the Saxon settlers who had been living alongside the Britons since the 430s. The reference to being pushed back from the sea may refer to Pictish and Irish raiders who were attacking the former imperial possession. Similar appeals were sent out in the 490s but met with no response.

Prolonged, though perhaps sporadic, war with Germanic invaders followed until, in 500, the British tribes, at last working together, achieved a victory at the battle of Badon. This effectively confined the invaders to the east for some time. But another is the Battle of Dyrham in 577, after which the significant cities of Bath, Cirencester and Gloucester fell and the Saxons reached the western sea. The battle is also considered by some to have been decisive since it drove a land wedge between the Britons of what was to become Wales or ‘Weallas’, meaning "the land of the foreigners" for Saxons and those in the south-west peninsula.

4. The fate of the Romano-Britons

England was “submerged by an Anglo-Saxon current which swept away the Romano-British”. The place-names and other linguistic evidence can be explained in that the Anglo-Saxons were politically and socially dominant in the south and east of Britain, meaning their language and culture also became dominant. But a lower figure of the number of the invaders is now generally accepted, making it highly unlikely that the existing British population was substantially displaced by the Anglo-Saxons. There is some archaeological evidence for Anglo-Saxons and Britons living on the same site. For example, in the cemetery at Wasperton, Warwickshire, it is possible to see one family adopting Anglo-Saxon culture over a long period.

Others may have lived in separate communities under the Anglo-Saxon rule. The laws of king Ethelbert of Kent, probably written in the early 7th century, make reference to a legal underclass known as laets who might represent British communities. There definitely is a British (wealh) underclass referred to in Wessex’s law code, written in the late seventh or early eighth centuries. Some Celts became slaves of the Saxons.

The violent nature of the period should not be overlooked, and it is likely that this period was a time of endemic tension, alluded to in all of the written sources. This may have led to the deaths of a substantial number of the British population. There are also references to plagues, though these would have affected the Anglo-Saxon and British populations equally. The evidence from land use suggests a slight decline in production, which might be a sign of population decline.

There is evidence for climate change in the 5th century, with conditions turning cooler and wetter. Dendrochronologists studying oak trees preserved in Irish bogs discovered what they believe to have been a disastrous climate event occurring in the late 530s. It was described as a disaster of catastrophic proportions, with indications of crop failures and widespread famine around the world. It was during this timeframe when plague spread throughout Europe, that dynasties began to collapse in China, Mexico and elsewhere. In Britain the shortened growing season made uplands unsuited to growing grain. Declining agricultural production from land that was already fully exploited had considerable demographic consequences.

It is clear that some British people migrated to the continent, which resulted in the region of Armorica in north-west Gaul becoming known as Brittany (whence its name), now part of France. There is also evidence of British migration to Hispania. The dating of these migrations is uncertain, but recent studies suggest that the migration from south-western Britain to Brittany began as early as 300 and largely ended by 500. These settlers, unlikely to be refugees given the early date, made their presence felt in the naming of the westernmost, Atlantic-facing provinces of Armorica, Cornouaille (‘Cornwall’) and Domnonea (‘Devon’). However, there is clear linguistic evidence for close contacts between the south-west of Britain and Brittany across the sub-Roman period.

In Galicia, in the northwest corner of the Iberian peninsula, another region of traditional Celtic culture, the Suevic Parochiale drawn up in about 580, includes a list of the principal churches of each diocese in the metropolitanate of Braga the ecclesia Britonensis, now Bretoña; it was the seat of a bishop who ministered to the spiritual needs of the British immigrants to north-western Spain: in 572 its bishop, Mailoc, had a Celtic name.

Anglo-Saxons pressed most of the native British groups, whom they called *walha- or 'Welsh', ever westwards, into the land which would become Wales, and Cornwall. These Celts, called Welsh by the Anglo-Saxons, called themselves cymry, "fellow countrymen". Some Celts were driven into Cornwall. In the west of Britain the period saw the creation of non-Anglo-Saxon kingdoms, which are first referred to in Gildas' De Excidio Britanniae. To an extent these kingdoms may have derived from Roman structures. However, it is also clear that they drew on a strong influence from Ireland, which had never been part of the Roman Empire. Archaeology has helped further our study of these kingdoms, notably at sites like Tintagel or the South Cadbury hill-fort.

In the north, other Celts were driven into the lowlands of the country, which became known as Scotland. There this period saw the development of the old northern British kingdoms of Rheged, Strathclyde, Elmet and Gododdin.