Now, when King Arthur left England to fight with Sir Lancelot, he ordered his nephew Sir Mordred to govern the land, which that false Knight did gladly. And as soon as he thought he might safely do so he caused some letters to be written saying that King Arthur had been slain in battle, and he had himself crowned King at Canterbury, where he made a great feast which lasted fifteen days. After it was over, he went to Winchester and summoned Queen Guenevere, and told her that on a certain day he would wed her and that she should make herself ready. Queen Guenevere’s soul grew cold and heavy as she heard these words of Sir Mordred’s, for she hated him with all her might, as he hated her; but she dared show nothing, and answered softly that she would do his bidding, only she desired that first she might go to London to buy all manner of things for her wedding. Sir Mordred trusted her because of her fair speech, and let her go. Then the Queen rode to London with all speed, and went straight to the Tower, which she filled in haste with food, and called her men-at-arms round her. When Sir Mordred knew how she had beguiled him he was wroth out of measure, and besieged the Tower, and assaulted it many times with battering rams and great engines, but could prevail nothing, for the Queen would never, for fair speech nor for foul, give herself into his hands again.
The Bishop of Canterbury hastened unto Sir Mordred, and rebuked him for wishing to marry his uncle’s wife. “Leave such desires,” said the Bishop, “or else I shall curse you with bell, book, and candle. Also, you noise abroad that my lord Arthur is slain, and that is not so, and therefore you will make ill work in the land.” At this Sir Mordred waxed very wroth, and would have killed the Bishop had he not fled to Glastonbury, where he became a hermit, and lived in poverty and prayed all day long for the realm, for he knew that a fierce war was at hand. Soon word came to Sir Mordred that King Arthur was hurrying home across the seas, to be avenged on his nephew, who had proved traitor. Wherefore Sir Mordred sent letters to all the people throughout the kingdom, and many followed after him, for he had cunningly sown among them that with him was great joy and softness of life, while King Arthur would bring war and strife with him. So Sir Mordred drew with a great host to Dover, and waited for the King. Before King Arthur and his men could land from the boats and ships that had brought them over the sea Sir Mordred set upon them, and there was heavy slaughter. But in the end he and his men were driven back, and he fled, and his people with him. After the fight was over, the King ordered the dead to be buried; and there came a man and told him that he had found Sir Gawaine lying in a boat, and that he was sore wounded. And the King went to him and made moan over him: “You were ever the man in the world that I loved most,” said he, “you and Sir Lancelot.” “Mine uncle King Arthur,” answered Sir Gawaine, “my death day has come, and all through my own fault. Had Sir Lancelot been with you as he used to be this unhappy war had never begun, and of that I am the cause, for I would not accord with him. And therefore, I pray you, give me paper, pen, and ink that I may write to him.” So paper and ink were brought, and Sir Gawaine was held up by King Arthur, and a letter was writ wherein Sir Gawaine confessed that he was dying of an old wound given him by Sir Lancelot in the siege of one of the cities across the sea, and thus was fulfilled the prophecy of Merlin. “Of a more noble man might I not be slain,” said he. “Also, Sir Lancelot, make no tarrying, but come in haste to King Arthur, for sore bested is he with my brother Sir Mordred, who has taken the crown, and would have wedded my lady Queen Guenevere had she not sought safety in the Tower of London. Pray for my soul, I beseech you, and visit my tomb.” And after writing this letter, at the hour of noon, Sir Gawaine gave up his spirit, and was buried by the King in the chapel within Dover Castle. Then was it told King Arthur that Sir Mordred had pitched a new field upon Barham Down, and the next morning the King rode hither to him, and there was a fierce battle between them, and many on both sides were slain. But at the last King Arthur’s party stood best, and Sir Mordred and his men fled to Canterbury.