Julius Caesar mounted two successive campaigns against the tribes of South-East England during the Summers of 55 and 54 bc(e). On both occasions he was forced to withdraw to the Continent due to a combination of the inclement British weather conditions and political machinations conducted to his rear by the disaffected among the recently-subjected Gallic tribes and by his enemies in the Roman Senate.
The Roman Invasion of Britain was mounted by the Praetorian Prefect Aulus Plautius during the reign of the emperor Claudius I in the summer of ad43. Plautius led an invasion force comprising four Roman Legions (II, IX, XIV and XX), supported by a substantial number of peregrine (i.e. non-Roman) auxiliary batallions; estimated to have numbered in excess of forty-thousand fighting men, perhaps as many as fifty- or sixty-thousand in total, including logistical components such as pack-mule and cart drivers and the naval ratings and officers who manned the vessels which transported the invasion force across the English Channel.
Hadrian's Wall runs for a distance of 80 Roman miles across Northern Britain from Newcastle-upon-Tyne in the East to the Solway Firth beyond Carlisle in the West. It was surveyed and engineered during the early reign of Emperor Hadrian, who visited Britain to oversee construction of his eponymous barrier c.ad122.
The historical period we now refer to as 'Roman Britain' ended in mid-ad410, when Rome itself was in danger of attack from raiding Germanic tribes like the Huns and the Visigoths. A delegation of leading British citizens was sent to petition the Emperor Honorius for military aid in their fight against ever more frequent sea-borne raids from Ireland and land-based devastations of the Scots and the Picts. The delegation was answered with the tacit reply that "Britain should look to it's own defences." Honorius had far more pressing problems to deal with, closer to home.
The 'Dark Ages'. So called due to the dearth of contemporary literary evidence from this period, leaving historians almost completely 'in the dark' when it comes to post-Roman Britain. These are the times in which the great stories of British folk mythology were told, an oral tradition only later committed to writing during Anglo-Saxon times. Many of these stories are available to the modern historian, in the Mabinogion of Welsh mythology, the Tain Bo Culaigh of Irish folk lore and the heroic Beowulf of English folk culture. Without doubt the most famous and most misunderstood of heroic stories from this age is that of King Arthur and his court of Camelot. Many of whose stories were committed to writing as late as Norman times.