Did you know that Charles VI, King of France from 1380 to 1422, believed he was made of glass?
Pope Pius II, who was born in the middle of the reign of Charles VI, wrote in his Commentaries that this caused him to protect himself in various ways so that he would not break.
For example, he insisted that iron rods should be inserted into his clothing to prevent him from breaking.
His bouts with madness, which seem to have begun in 1392, led to quarrels among the French royal family, which were exploited by the neighbouring powers of England and Burgundy. By the end of his reign much of France was under foreign occupation.