Sir Thomas Malory (d. 1471) spent much of his final 20 years in prison. During those decades he translated into English and rewrote the French Arthurian romances. Stories of Grail quests, lovelorn knights, and the Round Table had been wildly popular literature in the 12th and 13th centuries.
Eugene Vinaver writes in the 'Introduction' that Malory was 'a man bred up in arms who valued the dignity of knighthood above all else. Most of his knights are men of brief speech and unsophisticated behaviour. They engage in extraordinary adventures, but their motives admit of no sentimental refinement; they are first and foremost men of action.... [They live in] a world where vice is punished and injured men redress with their own hands the wrongs done to their honour.' (xv)

From the story "The Poisoned Apple": Queen Guinevere, accused of adultery, is about to be burned at the stake because no knight will fight in her defense. Her guilt or innocence is to be determined by the winning knight. If her champion wins, she will be proved innocent. If Sir Mador, her accuser, wins then she is guilty and will die. Suddenly a disguised knight (Sir Lancelot, her lover) "came from a wood there ... driving all that his horse might run." (123) The two knights battle.

"And then they rode to the lists' end, and there they couched their spears and ran together with all their mights. And anon Sir Mador's spear brake all to pieces, but the other's spear held and bare Sir Mador's horse and all backwards to the earth a great fall. But mightily and deliverly he avoided his horse from him [freed himself from his horse] and put his shield before him and drew his sword and bade the other knight alight and do battle with him on foot.
"Then that knight descended down from his horse and put his shield before him and drew his sword. And so they came eagerly unto battle, and either gave other many sad [heavy] strokes, tracing and traversing and foining together with their swords as it were wild boars, thus fighting nigh an hour; for this Sir Mador was a strong knight .... But at the last this knight smote Sir Mador grovelling upon the earth, and the knight stepped near him to have pulled Sir Mador flatling upon the ground; and therewith Sir Mador arose, and in his rising he smote that knight through the thick of the thighs, that the blood brast out fiercely.
"And when he felt himself so wounded and saw his blood, he let him arise upon his feet, and then he gave him such a buffet upon the helm that he fell to the earth flatling. And therewith he strode to him to have pulled off his helm off his head. And so Sir Mador prayed that knight to save his life. And so he yielded him as overcome, and released the queen of his quarrel [accusation]." (124-5)