Isabeau of Bavaria
Partisan use of the term "Burgundian" arose from a feud between John II, Duke of Burgundy and Louis of Valois, Duke of Orléans. The latter was the brother of King Charles VI, the former was his cousin. When madness interrupted the king's ability to rule they vied for power in a bitter dispute. Popular rumor attributed an adulterous affair to the Duke of Orléans and French queen Isabeau of Bavaria. Supporters of the two dukes became known as "Burgundians" and "Orleanists", respectively.