One of the Germanic tribes that invaded the Roman Empire, the Saxons later settled in Britain with the Angles and Jutes. Their origins are obscure but, by the third and fourth centuries AD, they were settled along the Baltic coast and in the area of modern Schleswig. They conducted pirate raids from their homelands to the south-east coast of Britain and this led the Britons to construct the Saxon shore forts. Curiously, however, in the fifth century the British leader Vortigern invited the Saxons to settle along the east coast, possibly to help to defend Britain from the seaborne raids of the Picts.
In the mid fifth century the Saxons called on other Germanic settlers (traditionally the Angles and Jutes) in Britain to rebel and their struggle with the British Celts marked the end of Roman rule in Britain.
By the close of the sixth century the struggle turned in the Saxons' favor and they gradually overran Britain, sweeping most of the Celts into Cornwall and Wales. The various Germanic tribes blended, conscious of their kinship with the continental Germans and the subsequent feeling of superiority over the Britons. On the continent the Saxons came into bitter conflict with the Frankish king Charles the Great (Charlemagne). In 18 battles over 32 years Charlemagne fought for the subjection and conversion of the pagan Saxons. He incorporated them into his empire after finally defeating them in the field and they were forcibly converted to Christianity.