When trial by ordeal worked ...
"Among the earliest duels upon record" was in AD878. Ingelerius, count of Gastinois, was found dead one morning by his countess in bed. Gontran, his relative, accused her of murdering him, having been unfaithful, and challenged her to produce a champion to prove his innocence.
Unfortunately for the countess, however, Gontran was a renown warrior, so no one dared to come to her aid, until her godson, Ingelgerius, count of Anjoy, who was only 16, stepped forward.
Everyone thought he had no hope, including the king, who sought to dissuade him from the enterprise, but he persisted in his resolution "to the great sorrow of all the court, who said it was a cruel thing to permit so brave and beautiful a child to rush to such butchery and death," however ...
"Gontran rode so fiercely at his antagonist, and hit him on the shield with such impetuosity, that he lost his own balance and rolled to the ground. The young count, as Gontran fell, passed his lance through his body, and then dismounting, cut off his head, which, Brantome says, 'he presented to the king, who received it most graciously, and was very joyful'."
I haven't checked it out, but a great story, and a reminder of the mentality of the age.
from Extraordinary Popular Delusions and the Madness of Crowds, C. Mackay, Wordsworth Reference 1995, (first published 1852) p. 656.