Anon he came fiercely towards Sir Gawaine, and they struck mightily together. They clove their shields and broke their helms and hauberks so that the blood ran down to their feet. At the last Sir Gawaine smote the knight so hard that he fell to the earth; and then he cried for mercy and yielded himself, and besought Sir Gawaine as he was a knight and gentleman to save his life.
"Thou shalt die," said Sir Gawaine, "for slaying of my hounds."
"I will make amends," said the knight, "unto my power."
Sir Gawaine would no mercy have, but unlaced his helm to strike off his head, when at that instant came his lady out of a chamber. She fell upon her husband just as the blow descended, and so Sir Gawaine smote off her head by misadventure, and the knight was saved.
"Alas!" said Gaheris, "that is foul and shamefully done; that shame shall never depart from you. Ye should give mercy unto them that ask mercy, for a knight without mercy is without honour."
Sir Gawaine was so astonished at the death of the fair lady that he knew not what he did, and he said unto the knight, "Arise, I will give thee mercy; and go thou unto King Arthur, and tell him how thou art overcome by the knight that went in the quest of the white hart."
"I care not for mercy now," said the knight, "for thou hast slain my lady that I loved best of all earthly things it matters not whether I live or die."
Then Sir Gawaine went into the castle and made ready to rest there all night.
"What will ye do?" said Gaheris; "will ye unarm you in this country? Ye may believe ye have many enemies here."
He had no sooner said that word than there came four knights well armed, and anon they made Sir Gawaine and Gaheris yield themselves as prisoners, in spite of the brave battle wherein Sir Gawaine was sore wounded in the arm.