Uther Pendragon, father of Arthur, loved Igraine, wife of the Duke of Cornwall. Through the magic of Merlin he visited her in the likeness of her husband who she did not know was dead. She then married Uther, and the child she bore was Arthur.

'Sir,' said she, 'the same night my lord was dead, there came into my castle of Tintagel a man like my lord in speech and countenance; and thus, as I shall answer unto God, this child was begotten'.
'That is the truth', said the king, 'for it was I myself, and I am father to the child'.
- Malory