His father was a nephew of Louise de La Vallière, the first official mistress of King Louis XIV of France.

In 1727 at the early age of nineteen, Louis César was promoted to the rank of colonel of the regiment under the title of duc de La Vallière.

Even though his father officially gave up the duchy in 1732, he was still styled at court as the duc de Vaujours.

Upon his father's death in 1739, Louis César became the new duc de La Vallière and was made the governor of Bourbonnais.

The property had been given to his father by his cousin, the princesse de Conti, in 1718 in order to settle some debts.

Between July 1757 and January 1759, he leased the estate to Madame de Pompadour for 12,000 livres per year.

In 1763, the duke finally sold Champs to Gabriel Michel de Tharon (1702–1765), a rich shipowner.

Part of the famous collection was acquired by the comte d'Artois, brother of Louis XVI and future king of France.

The duke also wrote two books: Ballets, opera, et autres ouvrages lyriques (1760) and the Bibliothèque du Théâtre-Français (1768, 3 vol.