"Not so," said Arthur; "ye have promised it me, and ye may not say nay."
So Tristram agreed to remain with King Arthur, who then went unto the sieges about the Round Table, and looked in every siege that lacked a knight. Then the King saw in the siege of Marhaus letters that said, "This is the siege of the noble knight Sir Tristram." And then Arthur made Sir Tristram knight of the Table Round with great splendour and great feast, as might be thought. For that Sir Marhaus, a worthy knight, was slain afore by the hands of Sir Tristram was well known at that time in the court of Arthur; and that for evil deeds that he did unto the country of Cornwall Sir Tristram and he fought; and that they fought so long tracing and traversing till they fell bleeding to the earth, for they were so sore wounded that they might not stand; and that Sir Tristram by fortune recovered, and Sir Marhaus died through the stroke on the head.
King Mark had had great despite of the renown of Sir Tristram, and therefore had chased him out of Cornwall. When now he heard of the great prowess that Sir Tristram did in England he was sore grieved, and sent men to espy what deeds he did. The Queen Isoud also on her part sent privily spies to know what deeds he had done, for great love was between them twain. When the messengers came home, and told that Sir Tristram passed all other knights at Arthur's court unless it were Sir Launcelot, King Mark was right heavy of the tidings, and as glad was the Fair Isoud. Then in great despite King Mark took with him two good knights and two squires, disguised himself, and took his way into England, to the intent to slay Sir Tristram.
So King Mark came into England, where he soon became known as the most horrible coward that ever bestrode horse; and there was much laughing and jesting at the knight of Cornwall, and much he was despised. Sir Dagonet, King Arthur's fool, at one time chased him through thick and thin over the forests; and when on a day Sir Launcelot overtook him and bade him turn and fight, he made no defence, but tumbled down out off the saddle to the earth as a sack, and there he lay still, and cried Sir Launcelot mercy.
So King Mark was soon brought as recreant before King Arthur, who already knew wherefore he was come into his country, and that he had not done the service and homage he owed as King Arthur's under-lord. But King Mark promised to make large amends for the wrongs he had done, for he was a fair speaker, and false thereunder. So on a day King Arthur prayed of him one gift, and King Mark promised to give him whatsoever he desired, if it were in his power. Then King Arthur asked him to be good lord unto Sir Tristram, and to take him back into Cornwall, and to cherish him for Arthur's sake. King Mark promised this, and swore upon a book afore Arthur and all his knights. Therewith King Arthur forgave him all the evil will that ever he owed him, and King Mark and Sir Tristram took either other by the hands hard knit together. But for all this King Mark thought falsely, as it proved afterward.
Then soon afterward King Mark took his leave to ride into Cornwall, and Sir Tristram rode with him; wherefore the most part of the Round Table were passing heavy, and some were wroth, knowing that King Mark was the most coward and the villainest knight living.
After a while letters came out of Cornwall that spake ill of Sir Tristram and showed plainly that King Mark took Sir Tristram for his mortal enemy. Sir Launcelot in especial made great sorrow for anger, wherefore Dinadan, a gentle, wise, and courteous knight, said to him: "King Mark is so villainous that by fair speech shall never man get of him. But ye shall see what I shall do. I will make a lay for him, and when it is made I shall make a harper sing it afore him."
So anon Dinadan went and made the lay, hoping thereby to humble the crafty king; and he taught it an harper named Eliot, and when he knew it, he taught it to many harpers. And so, by the will of Sir Launcelot and of Arthur, the harpers went straight into Wales and into Cornwall, to sing the lay that Sir Dinadan made of King Mark, which was the worst lay that ever harper sang with harp or with any other instrument.
At a great feast that King Mark made came in Eliot the harper, and because he was a curious harper, men heard him sing the lay that Dinadan had made, the which spake the most villainy of King Mark's treason that ever man heard. When the harper had sung his song to the end, King Mark was wonderly wroth, for he deemed that the lay that was sung afore him was made by Sir Tristram's counsel, wherefore he thought to slay him and all his well willers in that country.
So King Mark grew ever more jealous of Sir Tristram because of his prowess as knight and his great love and loyal devotion to the queen, the Fair Isoud; and by treason King Mark let take him and put him in prison, contrary to his promise that he made unto King Arthur. When Queen Isoud understood that Sir Tristram was in prison, she made as great sorrow as ever made lady or gentlewoman. Then Sir Tristram sent a letter unto her, and prayed her to be his good lady; and if it pleased her to make a vessel ready for her and him, he would go with her unto the realm of Logris, that is this land.