In the fourth century, Saxon pirate raids on the east coast of Britain were so common that it became known as the ‘Saxon Shore’. The coast was heavily fortified, but the frequent withdrawal of troops to fight in civil wars on the continent gave the Saxons plenty of opportunities to slip through the defences. Perhaps the Angles and Jutes joined in these raids too, but we do not know. The Britons never tried to distinguish between the different Germanic tribes that raided and settled in Britain - they just called the lot Saxons (Welsh Saesneg, Gaelic Sassenach): the convenient custom of calling these Germanic invaders ‘Anglo-Saxons’ was actually begun by the Franks across the Channel in Gaul. For their part, the Anglo-Saxons simply described the Britons as waelisc, that is ‘foreigners’, whence ‘Welsh’ and ‘Wales’.
Neither the exact date nor the circumstances of the first Anglo-Saxon settlements are known for certain. The traditional version of events, derived from Gildas and Bede, is that Vortigern invited the Saxons to settle in Kent in 449, three years after the Britons had appealed unsuccessfully to Rome for help against the Piets and Scots. The story of the subsequent rebellion of the Saxon leaders Hengest and Horsa, their calling in of reinforcements from across the North Sea and their treacherous slaying of the British leaders at a peace conference is a rattling good yarn but it is, alas, unlikely to be true. Archaeological evidence, most of it from pagan cemeteries containing warrior burials with Germanic weapons and metalwork, proves that Anglo-Saxon settlement actually began within a decade of the time that Britain became independent. By around the 450s Anglo-Saxons were settled in some numbers in Kent, the Thames valley. East Anglia, Lincolnshire and around the Humber estuary and York. If Vortigern did settle Angles or Saxons in Britain, they certainly were not the first. Possibly the Anglo-Saxons were unwelcome immigrants from the start, but it is not unlikely that British rulers invited the first settlers in. With the benefit of hindsight, this would seem not just unwise but positively reckless - Gildas said that it was like letting wolves into a sheepfold - yet settling Germanic tribes as ‘federates’ (allies) in return for military service was a long-established Roman practice and it would not be surprising if Romanised British rulers chose to emulate it. Nor would it be surprising if, once established, the Angles and Saxons took advantage of periods of British weakness or internecine strife to enlarge their territories, just as the Franks, Visigoths and other federates were doing at the same time in the Roman Empire.
By the end of the fifth century the Anglo-Saxons had seized control of most of south-east Britain. This was a considerable achievement for a group of tribal peoples with no common leadership and whose social and economic organisation was a lot less sophisticated than that which the Britons had inherited from the Romans or, for that matter, than the Britons had had even before the Roman conquest. Because it had the best farmlands, the south-east was the wealthiest region of Britain and supported the densest population. It was also the most Romanised part of the country, but this was not the advantage for the Britons it might seem. The traditional bonds of Celtic society were at their weakest here and it was also here that the Roman administration, with its tax collectors, had been at its most efficient. By the fourth century, the cost of defending the Roman Empire against German pressure was enormous. The rich, of course, used their influence to avoid paying taxes, so the burden fell heavily on the peasants, undermining their loyalty to the empire.
When the Roman frontiers finally collapsed in the fifth century, the invading Germanic tribes faced little popular resistance anywhere, not even in Italy. Conditions probably even got better for the peasantry under their new Germanic rulers, whose lack of administrative expertise made them inefficient tax collectors. The British elite of the south-east was proud of its Romanised lifestyle, but their enthusiasm is unlikely to have been shared by the peasants whose labour paid for it all. Lacking also the bonds of tribal solidarity, British resistance to the Anglo-Saxons probably collapsed quickly in the south-east. Once again, centralisation had failed the Celts and made them more vulnerable to conquest. It was a different matter in the less Romanised west and north, where the Iron Age tribal identities survived to provide a focus for loyalty and state formation; British resistance to the Anglo-Saxons continued here for centuries.