Mental illness inherited from his mother's family was very much part of his life. He was anorexic, ugly, debauched and brutal. Quite deranged, he tried to obtain as many favours from the crown as
possible. During the Fronde, he shared the adventurous life of his mother and, even though showing a lot of courage during the military campaigns of his father, it was not possible for him to be given a command even though he held rank as a lieutenant-general and afterwards field-marshal.
Aged twenty, he married Anna Henriette Julie, Countess Palatine, and they became the parents of ten children. He also fathered at least one illegitimate daughter.
He became more and more deranged and these bouts of madness lengthened as he grew older. At Chantilly, he was convinced that he had grown batwings and covered his room with wood and the ceiling with thick fabric to protect himself from bruising against the walls and floor when flying around.
In his hotel at Versailles, he thought that a fairy had changed him into a plant and demanded that his servants water him, and beat them if they didn't. The only way his servants could cope with this
was to join in, which would often bring him back to reason.
At one stage he thought he was dead and, as there is no need for food beyond the grave, fasted with application. If his servants, Girard and Richard, had not tricked him, he would have starved to
death. They covered themselves with cloth and pretending to be the Prince's grandfather and the late Marshall of Luxembourg, started a conversation with the Prince, then after a while invited him to join them for dinner. As obviously the dead do eat, he joined them readily as he was very hungry.
In his house, people regarded it all as exhilaration and excessive activity; but his wife, and victim, hid her bruises under her hats. Their daughters endured slave-like conditions, but shame and
fear sealed their mouths. His daughters were almost dwarfs, so small that the Duchesse de Bourbon called them "the dolls of the Blood".
At court people tried to pretend he was not there when barking like a dog. Only in presence of the King would he behave, the King would greet him with courtesy, pretending not to know about his
behaviour. He would imitate howling like a dog or wolf, according to the inspiration of the moment, though without sound. His extravagances knew no bounds.
Aged sixty-five, he died in Paris on 1 April 1709.
 

Source: Leo van de Pas