The disappearance or death of King Arthur is of the intriguing Arthurian legends . In some accounts, King Arthur was taken to the Isle of Avalon to be healed, and what happened to him after reaching the island is a mystery. Some say he lies in a cave awaiting the day he is needed again by his country, others say King Arthur he died at Avalon. Apart from the somewhat dubious claim by the monks at Glastonbury to have found King Arthur's grave in the Middle Ages, no real evidence has emerged for an Arthurian grave.
The earliest sources show us different and mutually incompatible concepts of his death emerged from local Arthurian folk-tales by the 10th-century at the latest. The early legends allow for the possibility of King Arthur returning, and claim that he is sleeping in a magical cave until Britain needs him again. Candidates for this cave are Alderley Edge and King Arthur Cave near the town of Ganarew. Some writers say he was transformed into a raven.
Then concept of King Arthur never having died appears in the Black Book of Carmarthen of the mid to late 9th-century may well represent much older traditions. The poem is a record of the burial places of ancient heroes, named as belonging "to legend and folklore rather than to history". The notion of Arthur’s future return was widespread by the 12th-century , and it was recorded in Breton, Welsh and Cornish folk lore
King Arthur is absent from Armes Prydein, a poem of the 10th-century in which ancient heroes are called upon to return to lead the British and their allies into battle against the Saxons -- if Arthur was as widely known and as popular a ‘hidden saviour’ in the 10th-century as some references suggest in the 12th-century, then his omission from this poem is very odd.
10th-century Annales Cambriae date Camlann by the internal chronology of the text, to either 537 or 539 (Geoffrey of Monmouth in the 12th-century dates it 542). Camlan became the symbol of calamitous defeat, so that when the last native prince of Wales was killed in 1282 the poet Gruffudd ab yr Ynad Coch saw it in terms of Arthur’s defeat: " as at Camlan".
The balance of probability is that King Arthur was a folk lore, rather than a historic, figure. He was portrayed as a ‘Protector of Britain’ who wanders across Britan with his band of chivilous knights. If this is the context then in his death either Camlann was a genuine historical conflict to which King Arthur's name was attached. Or that both the battle and Arthur were fork lore contrivings. The evidence that Camlan is a genuine historical conflict is weak. It is only first mentioned as a historical battle in a mid 10th-century document, over 400 years after it is supposed to have occurred.
So two traditions have emerged. Either King Arthur is still alive in Avalon, awaiting his moment to return, or he was killed in battle. The "still alive" version is the earlier version, while the "killed in battle" version arose later. By the 12th-century most of the written accounts relate to the of the Battle of Camlan, starting with Geoffrey of Monmouth’s Historia Regum Britanniae. The earliest references to Avalon and King Arthur’s death are found in Geoffrey of Monmouth’s chronicles. In Historia Regum Britanniae it is asserted that King Arthur "was mortally wounded" at Camlan but was then "carried off to the Isle of Avalon, so that his wounds might be attended to." In this ambiguous statement we can see Geoffrey is reconciling the concept of Arthur’s death in which he dies (King Arthur is mortally wounded) with that concept in which Arthur still lives (his wounds would be healed in Avalon).
The third, rather odd tradition, is that King Arthur turned into a raven, or perhaps Cornish Chough. The raven, this is a bird strongly associated with myth and legend. In Wales and the West Country, it was held to be a royal bird.