At the famous Battle of Agincourt peasants slaughtered thousands of knights. It was a decisive blood bath against a vastly superior force that allowed Henry V’s conquest of France. This is confirmed by eye witness records both French and English.
Most of the English soldiers who killed knights at Agincourt were longbowmen shooting from a distance and protected by both terrain and a line of sharpened stakes that prevented the French cavalry from charging them. That is not the kind of direct confrontation that the article is talking about.
Admittedly, the Flemish side wasn't exactly peasantry but largely townspeople in guilds, although in terms of the classic three-tier model (nobility, clergy, peasantry), they would have fallen into the last class.