ARTHUR, traditionally known as a sixth-century king of the Britons. Discussion of the origins of Arthur is of long standing. He is the hero or, later, the central figure of a large body of literature, much of it cyclic, in most western European languages but most especially in the medieval forms of French, German, English, and Welsh. He is consistently portrayed as a British ruler, and there is no doubt that his origins are to be sought in early Welsh sources and, to a lesser extent, in Breton and Cornish literature.

The evidence for Arthur's historical existence is meager and difficult to evaluate. Chapter 56 of the ninth-century Historia Brittonum, usually attributed to "Nennius," places him in the context of the first period of the attacks on Britain by the Germanic invaders, in the second half of the fifth century, and lists twelve of his famous victories. The chronicle...