A duel was arranged, and the butler, disarmed by Tristan, confessed his lie.

Tristan then produced the dragon's tongue and told his adventures; but, to the general surprise, instead of suing for Iseult's hand for himself, he now asked it in the name of his uncle, King Mark of Cornwall.
[Sidenote: The love potion.] The young princess was none too well pleased at this unexpected turn of affairs; but, as princesses never had much to say about the choice of a husband, she obediently prepared to accompany the embassy to Tintagel.

Her mother, wishing to preserve her from a loveless marriage, now sought out all manner of herbs wherewith to brew one of those magic love potions which were popularly supposed to have unlimited powers.
"Bethought her with her secret soul alone To work some charm for marriage unison, And strike the heart of Iseult to her lord With power compulsive more than stroke of sword." SWINBURNE, _Tristram of Lyonesse_.
This magic potion was put in a golden cup and intrusted to Brangwaine, the attendant of Iseult, with strict injunctions to guard the secret well, and to give the draught to her mistress and Mark to quaff together on their wedding day.
"Therefore with marvelous herbs and spells she wrought To win the very wonder of her thought, And brewed it with her secret hands, and blest And drew and gave out of her secret breast To one her chosen and Iseult's handmaiden, Brangwain, and bade her hide from sight of men This marvel covered in a golden cup, So covering in her heart the counsel up As in the gold the wondrous wine lay close." SWINBURNE, _Tristram of Lyonesse_.
Brangwaine carefully carried this potion on board the ship, and placed it in a cupboard, whence she intended to produce it when the suitable moment came.

Iseult embarked with the escort sent from Cornwall, and Tristan, in order to beguile the long, weary hours of the journey, entertained her with all the songs and stories that he knew.

One day, after singing for some time, he asked his fair young mistress for a drink; and she, going to the cupboard, drew out the magic potion, little guessing its power.
As was customary in those days in offering wine to an honored guest, she first put it to her own lips and then handed it to the thirsty minstrel, who drained it greedily.