End of Roman Britain
Claudius's invasion had begun in AD 43. By AD 47 the Romans had reached the Fosse Way, and they advanced further across Britain between AD 71 and 84. Hadrian's Wall was started in AD 122, and north of that, the Antonine Wall was built about the year AD 142. The attacks of the tribes in Scotland forced the Romans to retreat from this second wall by about AD 180. But they completely controlled the land south of Hadrian's Wall.
Roman rule had brought peace to southern Britain, but Rome itself was becoming weaker. Warlike tribes from central Europe attacked the Roman Empire's borders. Sometimes they swarmed across the frontiers. The Romans became more and more worried. Troops were brought back from Britain to help fight the barbarians.
Fewer Roman soldiers were left to protect Britain, and attacks on the provinces increased. The Piers raided from the north of Hadrian's Wall. Saxon sea-pirates from across the North Sea began to attack the cast and south coasts from the late third century onwards.
From about AD 270 the Romans began to build forts from Norfolk to Hampshire to protect the coastline closest to Europe. The Romans called these the Forts of the Saxon Shore, and their commander was known as the Count of the Saxon Shore. By AD 350 there were at least ten of these forts.
Each was rectangular in shape with 30 foot high walls and round towers to shoot catapults from.
The forts acted as bases for the Classis Britannica, the Roman fleet in Britain. This consisted of fast, light scout-ships, camouflaged in sea green or blue, and powered by twenty oarsmen. The forts and fleet were meant to guard harbors and river-mouths from attack and to drive away invaders .
In AD 286 Carausius, the commander of the Classis Britannica, rebelled against the Emperor Diocletian and set himself up as 'the Emperor in Britain'. He took soldiers from all over Britain to help fight off an attack by the Roman Emperor's armies, and this civil war lasted ten years. By this time, the Piers had overrun the weakened Hadrian's Wall, and it took some years to drive them back.
But the attacks continued. In AD 343 things were so bad that the Emperor Constans crossed the Channel in winter to visit the wall personally.
The worst attack came in AD 367. The Picts, Saxons and Scots launched attacks at the same time, and the weakened Roman legions couldn't resist them. The Count of the Saxon Shore was killed in battle, the Scots raided as far south as Kent, and London was besieged. For almost a year people lived in fear as invaders destroyed villas, towns and villages.
In the end the Emperor Theodosius restored order, but life never returned to normal.
In AD 383 the Emperor Maximus took more troops from Britain. The Picts again saw this as an opportunity to attack Hadrian's Wall. They completely overran it, and the wall was never refortified. The boundaries of Roman Britain were shrinking.
By this time the Saxons weren't just raiding Britain. In some places the British chiefs realized that the Romans could no longer protect them. They invited Saxon leaders into Britain to settle, if they promised to help drive off other invaders.
In AD 401 the Emperor Honorius took still more troops away to defend Rome, and in AD 407 the military commander took away perhaps the last Roman soldiers in Britain to fight in Gaul. In AD 410, when the Britons pleaded with the Emperor for help against the Saxons, they were told they would have to defend themselves. Even the city of Rome was now surrounded by enemies, and Roman Britain was at an end.