'Who slew him?' asked Sir Gawaine.
'Sir Lancelot slew them both,' answered the man.
'He cannot have slain Sir Gareth,' replied Sir Gawaine, 'for my brother Gareth loved him better than me and all his brethren, and King Arthur too. And had Sir Lancelot desired my brother to go with him, he would have turned his back on us all. Therefore I can never believe that Sir Lancelot slew my brother.'
'Sir, it is in everyone's mouth,' said the man. At this Sir Gawaine fell back in a swoon and lay long as if he were dead. Then he ran to the King, crying, 'O King Arthur, mine uncle, my good brother Sir Gareth is slain, and Sir Gaheris also,' and the King wept with him. At length Sir Gawaine said, 'Sir, I will go and see my brother Sir Gareth.'
'You cannot do that,' returned the King, 'for I have caused him to be buried with Sir Gaheris, as I knew well that the sight would cause you overmuch sorrow.'
'How came he, Sir Lancelot, to slay Sir Gareth?' asked Sir Gawaine; 'mine own good lord, I pray you tell me, for neither Sir Gareth nor Sir Gaheris bore arms against him.'
'It is said,' answered the King, 'that Sir Lancelot slew them in the thickest of the press and knew them not. Therefore let us think upon a plan to avenge their deaths.'
'My King, my lord and mine uncle,' said Sir Gawaine, 'I swear to you by my knighthood that from this day I will never rest until Sir Lancelot or I be slain. And I will go to the world's end till I find him.'
'You need not seek him so far,' answered the King, 'for I am told that Sir Lancelot will await me and you in the Castle of Joyous Gard, and many people are flocking to him. But call your friends together, and I will call mine,' and the King ordered letters to be sent throughout all England summoning his Knights and vassals to the siege of Joyous Gard. The Castle of Joyous Gard was strong, and after fifteen weeks had passed no breach had been made in its walls. And one day, at the time of harvest, Sir Lancelot came forth on a truce, and the King and Sir Gawaine challenged him to do battle.
'Nay,' answered Sir Lancelot, 'with yourself I will never strive, and I grieve sorely that I have slain your Knights. But I was forced to it, for the saving of my life and that of my lady the Queen. And except yourself, my lord, and Sir Gawaine, there is no man that shall call me traitor but he shall pay for it with his body. As to Queen Guenevere, oft times, my lord, you have consented in the heat of your passion that she should be burnt and destroyed, and it fell to me to do battle for her, and her enemies confessed their untruth, and acknowledged her innocent. And at such times, my lord Arthur, you loved me and thanked me when I saved your Queen from the fire, and promised ever to be my good lord, for I have fought for her many times in other quarrels than my own. Therefore, my gracious lord, take your Queen back into your grace again.'