This duke had at least thirteen sons. Gawaine slew seven, for which cause the duke and his remaining six sons were Arthur and his knight’s sworn enemies.
Therefore, when Sir Marhaus arrived with the damsel Été and introduced himself – perhaps a trifle prematurely – as a knight of the Round Table, the duke gave him hospitality for the night but informed him regretfully that on the morn he would have to battle his host and his host’s six sons. Marhaus defeated them all and sent them to Arthur’s court that Whitsuntide, where they were all reconciled to the King.
See also
South Marches | The Legend of King Arthur
Source
Le Morte Darthur | Sir Thomas Malory, 1469-1470