Many people think Arthur was a historical figure of the fifth or sixth centuries. This is not a view I share, which is why I generally leave Arthur aside when discussing early medieval topics. My own view is the one encapsulated by Oliver Padel in 1994, when he examined the key question: Did Arthur exist? Padel suggested that Arthur originated in legend as “a pan-Brittonic figure of local wonder-tales” like the mythical Irish hero Fionn (Finn Mac Cool). The two figures share much in common: both appear in tales of magical beings and places; both were associated with mysterious prehistoric monuments; both were portrayed as saviours of their homelands. Padel argues that just as Fionn made the transition from Irish legends to Irish historical texts, so Arthur made the same transition in a British context, becoming a key figure in pseudo-history as well as remaining an important character of folklore. Hence the list of Arthur’s battles in the Historia Brittonum of c.830, and hence his appearance in the Welsh Annals, while a parallel tradition continued to weave him into tales such as Culhwch and Olwen. But there was no real Arthur, according to Padel, unless the legendary figure was created partly out of a folk-memory of the Roman centurion Lucius Artorius Castus (who led an army from Britain to Gaul in c.200).
Views such as the one expressed by Padel are obviously unpopular with supporters of the Historical Arthur but, when the early medieval sources are examined, the absence of this enigmatic figure is very noticeable. Neither Bede nor Gildas mention him, so why should we regard him as important?
Oliver Padel, ‘The nature of Arthur’. Cambrian Medieval Celtic Studies 27 (1994), pp.1-31