Charles VI of France

Charles VI suffered his first major episode of madness while on a military campaign in Brittany. He killed several of his own knights in a fit of frenzy. This began a lifelong pattern of intermittent insanity that crippled royal authority.

Charles VI's reign saw the outbreak of a civil war between the Armagnac and Burgundian factions, who fought for control of the mad king. This internal conflict weakened France and allowed Henry V of England to conquer much of the kingdom.

Charles VI signed the Treaty of Troyes, which disinherited his son, the future Charles VII, and recognized Henry V of England as his heir. This treaty was forced by the Burgundian faction and effectively made France a dual monarchy with England.