Answer:
Sir Gawain advise King Arthur to talk peace with Modred, then wait for Lancelot.
Step-by-step explanation:
When Sir Gawain is about to die he writes a letter to Lancelot where it says:
'You are the best knight in the world,' he wrote, 'and you have always done what you thought was right. I want the world to know that I have been at fault in the war between us. Now I am dying and I beg you to come home to England and help the king in his struggle against Sir Mordred.'
Then after his death, he warns King Arthur in a dream where he says:
'If you fight tomorrow,' 'you will be killed. You must wait until Sir Lancelot arrives from France to help you.'