When Sir Tristram landed he saw Sir Marhaus waiting armed in the shadow of his ship. Sir Tristram's squire brought his master's horse to land, and clad his master in his armour as was right, and then the young knight mounted upon his horse and rode towards Sir Marhaus.
While he was as yet six spear-lengths from him the knight of the Round Table cried unto him:
'Young knight, Sir Tristram, what doest thou here? I grieve me of thy courage, for ye are untried, while I have been well essayed in jousts and tournaments with some of the best men of their hands as are now living. I counsel thee to go back.'
'Fair and well-proved knight,' said Sir Tristram, 'I am for thy sake made knight, and I have promised to fight thee, and I will do so, as much for mine uncle's sake as for what worship I may win from doing battle with ye, who are one of the best renowned knights of the world.'
'Then I would have ye know, fair sir,' said Sir Marhaus, 'that no worship shalt thou lose if thou canst only stand against three strokes of mine, for, by reason of my noble deeds, seen and proved, King Arthur made me knight of the Round Table.'
Sir Tristram answered him naught, and then they dressed their spears and spurred their horses, and ran so fiercely each against the other that both were smitten to the ground, both horses and men. But Sir Marhaus had struck a great wound in the side of Sir Tristram, yet so eager was the young knight that he knew not of it. They leaped up and avoided their horses, and drew out their swords, and with shield on arm they lashed at each other like fierce wild boars. Yet for all Sir Marhaus' strong and bitter strokes he could not beat down the young knight's guard, and in despite he began to aim at his vizor and his neck. At this Sir Tristram was wroth, and struck him more furiously. Thus for two hours the battle waged, and both were sore wounded. But Sir Tristram was the fresher and better winded and bigger of limb and reach; and suddenly he heaved his sword up high, and closing upon Sir Marhaus he smote him with so mighty a buffet upon his helm that the blade shore through the steel even into the brain-pan.
So fierce had been the stroke that the sword stuck fast in the bone and the helmet, and Sir Tristram pulled thrice at his sword before it would loosen. Sir Marhaus sank to his knees with a deathly groan; then he threw away his sword and shield, and rising, staggered away towards his ship. Sir Tristram swooned and fell; and his squire came running to him, just as the men of Sir Marhaus' ship came and drew their master on board. Then they swiftly set their sail and flew over the sea.
Great was the mourning of the barons and the people of Cornwall when it was known how deep and wide was the wound which Tristram had received from the lance of Sir Marhaus. Many famous leeches came and searched the wound and strove to close it, but none availed. When two months had passed, came an old, old woman, a witch wise in leechcraft beyond all others, who was called the Mother of the Mists, and who lived in the Great Shuddering Moor, where only trolls dwelled, and no man ever dared to go. She also came and searched his wound at the king's desire.
When she had made her search, with many mumblings and strange words, she turned and looked keenly at the king. Her eyes gleamed like beads, her skin was wrinkled and dark, and she laughed a little soft laugh.
'Lord king,' she said, 'this fine man's wound is poisoned, and naught can heal it this side the great water. But if he goeth whither the spear came from which poisoned it, he shall get whole of that wound.'