controller general who, under King Louis XIV, directed the financing and provisioning of the French army during the first half of the War of the Spanish Succession (1701–14).

After serving as intendant at Rouen, Chamillart was made intendant of the finances of the kingdom in 1690. He was appointed controller general of finances in 1699 and minister of state the following year. He became secretary of state for war in 1701, shortly before France engaged the Austrians, the British, and the Dutch in the War of the Spanish Succession.

Chamillart had originally won the king's favour through his honesty and his skill at billiards. He lacked talent for fiscal administration and relied heavily on his able assistant, Nicolas Desmarets (Desmarets, Nicolas, Marquis De Maillebois), to raise money for the war. Forced to resort to unpopular and unsound financial measures, he was blamed by his countrymen for the severe economic hardships they were suffering. Nevertheless, Chamillart deserves much of the credit for reorganizing the French armies after the defeats of 1704, 1706, and 1708. Recognizing the impossibility of his task, he attempted to resign in 1706, but Louis XIV insisted that he remain in office. Ill health caused him to turn over the finances to Desmarets in February 1708, and the following year Louis removed him from his remaining posts.