Le Savage Damsel

Then he drew his sword Excalibur, but it was so bright in his enemies' eyes, that it gave light like thirty torches. And therewith he put them a-back, and slew much people. And then the commons of Carlion arose with clubs and staves and slew many knights; but all the kings held them together with their knights that were left alive, and so fled and departed. And Merlin came unto Arthur, and counselled him to follow them no further.

He who wants to do more than he is able must admit defeat or retire.

I myself beheld the King Charge at the head of all his Table Round, And all his legions crying Christ and him, And break them; and I saw him, after, stand High on a heap of slain, from spur to plume Red as the rising sun with heathen blood, And seeing me, with a great voice he cried, "They are broken, they are broken!" for the King, However mild he seems at home, nor cares For triumph in our mimic wars, the jousts— For if his own knight cast him down, he laughs Saying, his knights are better men than he— Yet in this heathen war the fire of God Fills him: I never saw his like: there lives No greater leader.

And when this was done Merlin said, Fair sirs, you must all arise and come to King Arthur for to do him homage; he will have the better will to maintain you.  And so they arose and did their homage, and when they were gone Merlin found in every sieges letters of gold that told the knights' names that had sat therein.  But two sieges were void.