In Morte d'Arthur, King Arthur is given a prophetic dream from Gawaine. Book XXI Chapter III Gawaine says,
“God given me leave, for to warn you of your death; for an ye fight as to-morn with Sir Mordred, as ye both have assigned, doubt ye not ye must be slain, and the most part of your people on both parties. And for the great grace and goodness that almighty Jesu hath unto you, and for pity of you, and many more other good men there shall be slain, God hath sent me to you of his special grace, to give you warning that in no wise ye do battle as to-morn, but that ye take a treaty for a month day; and proffer you largely, so as to-morn to be put in a delay. For within a month shall come Sir Launcelot with all his noble knights, and rescue you worshipfully, and slay Sir Mordred, and all that ever will hold with him.”
This dream warns Arthur that if he engages in combat with Sir Mordred before Sir Launcelot arrives that he and most of his men will die.
There is one major hindrance that thwarts Arthur’s attempt to heed the dream, the mutual hatred between Arthur and Mordred which is powder keg that is ignited by a snake. The reader see’s Arthur’s hatred and distrust in Book XXI Chapter IV as he leaves his men “he warned all his host that an they see any sword drawn: Look ye come on fiercely, and slay that traitor, Sir Mordred, for I in no wise trust him.” Here Arthur knowing full-well that to engage in combat will result in his and several others death, he gives a very strict order. This hatred and distrust is mirrored in Sir Mordred when he “warned his host that: An ye see any sword drawn, look that ye come on fiercely, and so slay all that ever before you standeth; for in no wise I will not trust for this treaty, for I know well my father will be avenged on me.” If not for Arthur and Mordred’s mutual distrust their men would not be on edge just waiting for something to set them into combat. It could be argued that the adder was what sparked the battle but the adder’s bite would not have done anything if the men were not on edge already. In Book XXI Chapter IV it states,
“Right soon came an adder out of a little heath bush, and it stung a knight on the foot. And when the knight felt him stung, he looked down and saw the adder, and then he drew his sword to slay the adder, and thought of none other harm. And when the host on both parties saw that sword drawn, then they blew beams, trumpets, and horns, and shouted grimly.”
The quick response to a sword being drawn would not have started such an uproar if the men had not been warned to look for the slightest provocation.
Arthur has one final attempt to escape his fate.
Sir Lucan says, “Good lord, remember ye of your night's dream, and what the spirit of Sir Gawaine told you this night, yet God of his great goodness hath preserved you hitherto. Therefore, for God's sake, my lord, leave off by this, for blessed be God ye have won the field, for here we be three alive, and with Sir Mordred is none alive; and if ye leave off now this wicked day of destiny is past. Tide me death, betide me life, saith the king, now I see him yonder alone he shall never escape mine hands, for at a better avail shall I never have him.” Arthur looking at the destruction around him cannot let his hatred of Mordred pass and he goes to kill Mordred. He stab’s Mordred with a spear and Mordred pulls himself up the spear to stab Arthur striking a fatal blow. It is their mutual hatred that causes the down-fall of Arthur, such a hatred that even God’s intervention in the dream cannot save Him.