Mordred makes himself King of England and incestuously claims Guinevere as his wife. Guinevere escapes to the Tower of London. The Bishop of Canterbury reproaches Mordred for his usurpation and would-be incest, and when Mordred tries to kill him, he flees and becomes a hermit. Mordred wins many Englishmen to his side, then meets Arthur at Dover but is forced to retreat from him.
In this battle Gawain is mortally wounded. As he dies he admits to Arthur that if it were not for his insane pride in insisting on unjust revenge, Launcelot would be here now to save the kingdom; then he writes Launcelot, begging him to come help Arthur and also to pray at his tomb. Then, bleeding from the wound he got originally from Launcelot — with the fated sword of Balyn — Gawain dies.
Arthur meets Mordred again at the battle of Bareon Down and again puts him to flight. They meet next at Salisbury Plain, and there, with all who loved Launcelot fighting on Mordred's side, they prepare for what is to be their last battle. The night before the battle, Arthur dreams he is on the Wheel of Fortune, sitting on a throne and dressed in the richest gold that can be made:
And the kynge thought there was undir hym, farre from
hym, an hydeous depe blak watir, and therein was all
maner of serpentis and wormes and wylde bestis fowle
and orryble. And suddeynly the kyrige thought that the
whyle turned upso-downe, and he felle anionge the
serpentis, and every beste toke hym by it lynnue. And
than the kynge cryed as he lay in hys bed, "Helpe!
Helpe!"
