Failing to understand the ability to pull a sword from a stone as a valid claim on the throne of England, the Eleven Kings of the north rebel against King Arthur as soon as he receives the crown. Loving peace, Arthur wages total war:
The King of England had ordered that there were to be no ransoms in his sort of battle. His knights were to fight, not against gallowglasses, but against the knights of the Gaelic Confederation. Let the gallowglasses fight among themselves if they must—indeed, since there was a real aggression for them to settle, apart from the question of ransoms, let them fight to the best of their ability. But, as for his nobles, they were to attack the nobles of the rebels as if they were gallowglasses and nothing more. They were to accept no composition, observe no ballet-dancer’s rules. They were to press the war home to its real lords—until they themselves were ready to refrain from warfare, being confronted with its reality.
Afterwards, he knew for certain now, it was to be the destiny of his life to deal with every way of twisting decency by threats of Power.
So we may well believe that the King’s men were shriven on the night before they fought. Something of the young man’s vision had penetrated to his captains and his soldiers. Something of the new ideal of the Round Table which was to be born in pain, something about doing a hateful and dangerous action for the sake of decency—for they knew that the fight was to be fought in blood and death without reward. They would get nothing but the unmarketable conscience of having done what they ought to do in spite of fear—something which wicked people have often debased by calling it glory with too much sentiment, but which is glory all the same. This idea was in the hearts of the young men who knelt before the God-distributing bishops—knowing that the odds were three to one, and that their own warm bodies might be cold at sunset. (T.H. White, The Once and Future King)