The son of Louis Charles, 12th duc de Thouars and his wife, Hélene Pillet-Will (heiress of Count Frédéric Pillet-Will, the Parisian banker who bought the Château Margaux wine label in 1879), La Trémoïlle was a member of the 1er régiment de chasseurs d'Afrique, a French army regiment.
He was killed in a fire at the estate of Leander J. McCormick in Whitchurch, Hampshire, England, at the age of 23.