"There is some historical evidence for an actual Arthur, who was most likely a Romanized Celt. According to annals, a Celtic leader named Artorius, for a brief period in the fifth century A. D., enjoyed some success against invading Anglo-Saxons, Germanic tribes who ultimately displaced the Celts of England. A sixth-century monk named Gildas, in his On the Ruin of Britain, and the Venerable Bede in his eighth-century Ecclesiastical History, describe the fate of the Celts. Gildas and Bede both mention Badon Hill, a battle site later associated with Arthur, but neither make explicit reference to Arthur. It is not until the ninth century that Nennius, who dubbed himself "historiographer of the Britons," first mentions Arthur. Already the stuff of legend, Nennius’s Arthur is credited with single-handedly slaying 940 Saxons at Badon Hill. Such exaggerations are common in medieval histories, which were more concerned with implicit truths than facts. So, from the earliest accounts, Arthur is attributed with larger-than-life heroic qualities. Because the Celts and the early Anglo-Saxons were oral cultures, stories about Arthur spread quickly and acquired new meaning with new generations. And so the actual Arthur, if he ever existed, is dwarfed by the legend, which became the vogue about 700 years after the "real" Arthur would have lived.
In the twelfth-century, historian Geoffrey of Monmouth recorded, some say invented, the legend of Arthur as it has been subsequently handed down. Among his sources were Bede, Gildas, Nennius, and, primarily, "a very ancient book" which has never been recovered and which some doubt ever existed. Geoffrey is the first to mention Merlin, Uther, Ygraine, Tintagel, and Avalon. Geoffrey’s work is filled with flight and fancy, sprinkled with fights involving giants and numerous magical occurrences. Geoffrey’s Arthur is so powerful, so exaggerated, that he comes close to defeating the Roman Empire itself. Although the History was not criticized in Geoffey’s life, it came under attack in 1198 by William of Newburgh, who called it a "fable" and a "fiction." Nonetheless, Geoffrey’s work was influential on subsequent chronicles. But the Arthur in these works is displaced by time, rendering his actual existence impossible to determine definitively.
Archeologists have joined in attempts to prove Arthur’s existence by locating Camelot and by unearthing the king’s tomb. Cadbury Hill, obviously the site of a large fortress, would have been occupied during the approximate years of the historical Arthur’s reign and is sometimes identified as Canterbury. At Glastonbury Abbey, a stone slab with an inscription that read "Arthur" was unearthed in the twelfth century and a body was exhumed. In the fourteenth century, this body was again exhumed and, in the process, badly damaged and subsequently lost. Could this be our Arthur? Again, there is no substantial evidence.
Perhaps Arthur’s historical existence is, in the end, a moot point. Regardless of his actual existence, his literary presence in twelfth-century Europe was profound."