At first starting out on a career in the church, Chamillart changed his career by buying an appointment as councilor of the parliament of Paris in 1674. He became acquainted with the king in 1684 and played billiards with him three times a week. He then became Maître des Requêtes in 1686 and intendant des finances in 1690. He now found the favor of Madame de Maintenon, and in 1699 succeeded Louis de Pontchartrain as contrôleur general des finances (secretary of finance) and became ministre d'état. In January 1701 he also succeeded Barbezieux as secretary of war, uniting the finance and the war ministry.
Chamillart was not a great networker and did not mingle in court life, instead solely leaning on royal favor. Having not many friends he tried to appease his many critics by handing over his position as contrôleur general to Nicolas Desmarets in February 1708. But this was not enough, his critics blamed him for almost every disaster that France lived through, and though there were no specific griefs against Chamillart, Louis saw no choice but to sack him in June 1709. He was succeeded by Voysin.
By historians his professional performance is often characterized as weak, incompetent or as a mediocre executer of orders. As I have not found (nor tried to find) anything to support these characterizations, I will for the moment think that he was a mediocre but capable and honest servant of Louis.
The description given of him by Saint Simon stresses two things: His honesty in affairs (an exception in those times and thus very important), and his limited intelligence (but very good memory and command of language). Simon states that Chamillart fell out of favor with Maintenon by once proposing a plan to the king without informing her beforehand and that she was the instigator of his dismissal.
Emmanuel Penicaut has written an excellent article about Chamillart, and it is on the net at http://theses.enc.sorbonne.fr/index.html
- 1674: Councilor of the parliament of Paris
- 1686: Maître des Requêtes
- 1690: Intendant des finances
- 1699- 1708 Controleur General des Finances
- 1702- 1709 War secretary