Fate is known as the power supposed to determine the outcome of events. I would classify King Arthur's death in "The Day of Destiny" as fate. The two dreams that Arthur experienced were predictions and warned him of what was to come. Even though Arthur was forewarned of his future misfortune, his death, as the ending result, proves that one cannot control his own destiny.
The first dream that Arthur had was the dream of the chair and wheel. Arthur dreamt that he was sitting on a chair, which could represent the throne, and the chair was attached to a wheel. The dream started out wonderfully with Arthur adorned in "the richest cloth of gold", as a king would be, but then suddenly the dream turned ugly and the wheel turned Arthur upside down, allowing him to fall into the deep dark water where he was killed by serpents and beasts. The dream encompasses two meanings; Arthur's reign as king was to going to come to an end and his life as well would end. The second dream was the warning from Sir Gawain. He told Arthur that God had sent him to Arthur to warn him of his death and it would be in his best interest to not go to battle with Sir Mordred, but to wait a month. Sir Mordred and Arthur both agreed to wait a month to battle, but neither one was trusting in the other. King Arthur thought that he was changing the future and that he had the power of his destiny in his own hands by listening to his dreams.
Because both King Arthur and Sir Mordred didn't trust one another, they warned their men that if a sword were drawn at anytime, their battle would begin. Fate, disguised as an adder (a poisonous snake), altered the destiny of King Arthur once more. "Right so came an adder out of a heath-bush, and it stung a knight in the foot. And so when the knight felt him so stung, he looked down and saw the adder; and anon he drew his sword to slay the adder, and thought none other harm.