On 26 Mar 1351 the Combat of the Thirty was an arranged fight between selected combatants from both sides of the conflict, fought at at Guillac, a site midway between the Breton castles of Josselin and Ploërmel among 30 champions, knights, and squires on each side.

Robert Knollys (age 26) took part.

Hugh Calverley (age 27) fought, was captured and ransomed.