The battle of Camlan was the last of Arthur's battles, and that in which he lost his life. Legend gives his opponents as headed by Medrawd, the son of his sister Anna and Llew ap Cynvarch. In the later standard legend, Mordred is Arthur's son by an incestuous relationship with his half-sister, Morgause, wife of King Lot of the Orkneys.
   The Triads assign two different causes for this battle. The first, the blow given by Gwenhwyvar, Arthur's wife, to Gwenhwyvach; the other, the blow given to Medrawd by Arthur himself.
   Lady Guest in her Mabinogion Notes provides us with her version of the events immediately preceding it, together with the account of the battle itself as related in the Triads, and by Gruffydd ab Arthur (Geoffrey of Monmouth):
   "Lles, emperor of Rome, demanded from Arthur the tribute that his ancestors had paid, from the time of Caswallawn the son of Beli to that of Cystennin, Arthur's grandsire.
   The Roman Ambassadors proceeded to Caerlleon upon Usk, when Arthur not only denied their claim, but on the ground of the British origin of Bran and Constantine, both Roman emperors, determined by a counterclaim to retaliate. Medrawd was appointed Regent of the kingdom, whilst Arthur and his Britons crossed the sea, and fought a battle in the Cisalpine territory, in which the Roman emperor was slain, and both parties sustained severe loss. The result of this encounter encouraged Medrawd to attempt his uncle's throne. He seized upon the royal residence of Gelliwig, dragged the queen Gwenhwyvar from her throne (or, according to some versions, appropriated her as his wife), and strengthening himself by making treaties with the Saxons, Scots, and Picts, collected a force of eighty thousand men to oppose his uncle's landing. Arthur, however, disembarked at Porth Hamwnt, and put his rebellious nephew to flight after a hard fought engagement. Medrawd retreated to Winchester, whither Arthur, after remaining three days on the field of battle to bury the dead, followed him, and gained a second victory; upon this Medrawd fled  into Cornwall, but was overtaken on the banks of the Camlan, supposed to be the river Camel, in that county. The celebrated battle of Camlan ensued. Arthur there gained the victory, but received a mortal wound at the hand of Medrawd, whom, however, he slew upon the field; he did not himself die on the spot, but was conveyed to Avallach or Avalon, and the crown descended to Cystennin the son of Kadwr, his kinsman. A mystery hangs over the final fate of Arthur.
   One of the Triads admits that Arthur died, and was buried at Avalon, now Glastonbury, in Somersetshire, where we learn from other authorities that Henry the II. many years afterwards discovered what were said to be his remains."
   Malory has only Arthur, Bedivere and Lucan survive this battle. Arthur was sorely, perhaps mortally, wounded and taken to Avalon. In Culhwch and Olwen, a number of other survivors are mentioned including Sandav, because he was so beautiful that all mistook him for an angel, and Morvran, because he was so ugly that all supposed him a devil. Other variations of the battle have Saint Derfel and Saint Petroc survive. Welsh tradition speaks of seven survivors, a magic number similar to the seven that returned from Caer Sidi in the Spoils of Annwn poem.
   The date and location of the battle continue to be debated. The Annales Cambriae state it was twenty-one years after Badon. Geoffrey seems to indicate that it was in 542. The Irish Annals of Tigernach place it in 541 and the Spanish Anales Toledanos in 580. Slaughter Bridge on the River Camel in Cornwall is a traditional site as evidenced in Lady Guest's comments above. Other studies place it in Wales or at Camboglanna or as with Riothamus on the continent. The Didot Perceval even places it in Ireland.
   In Malory, Mordred's and Arthur's armies first clash at Barham Down. Arthur carries the day and Mordred retreats to Canterbury. Arthur camps at Salisbury where he has the vision of Gawain's ghost. The embassy Arthur sends to meet with Mordred find him "where he has a grim host of a hundred thousand men" and can be presumed to be somewhere between Salisbury and Canterbury. The battlefield itself is unnamed in Malory.