|Birth||8 February 1910 (Paris)|
|Death||9 December 1933|
Louis Jean Marie de La Trémoïlle (8 February 1910 – 9 December 1933), prince and 12th duc de La Trémoïlle, 13th duc de Thouars and premier duke of France, 13th prince de Tarente and 17th prince de Talmond was a French soldier.
He was the last male of one of the most historically significant noble families of France. His accidental death before his 25th year extinguished the last but one (i.e., the House of Rohan) of France's most renowned prince étranger families, whose struggles and alliances with the Valois and Bourbon kings of France constitute no small part of the history of the ancien régime.
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. Some noted at the time that his mysterious death by fire in England evoked the martyrdom at English hands of Joan of Arc five centuries earlier, who had been betrayed by the young duke's ancestor, Georges de la Trémoille, founder of the fortune of the House of La Trémoïlle. He died unmarried and left no known descendants.
Although the 1944 Almanach de Gotha states that his successor as 14th duchesse de Thouars was the eldest of his four sisters, Princess Charlotte (1892-1971), the Genealogisches Handbuch des Adels of 1991 refrains from doing so, and a 1959 ruling of the French courts declared that hereditary titles may only be transmitted "male-to-male" in "modern law". (The original grant of the dukedom, in July 1563 by Charles IX, stipulated that it was heritable by both male and female successors, although when erected into a pairie by King Henri le Grand in 1599, the letters patent restricted succession to the peerage to male heirs).
The duke's nephew, Jean Charles Lamoral, as the only son of his eldest sister, had de La Trémoïlle appended to his own princely surname in the Kingdom of Belgium as "Prince de Ligne de La Trémoïlle" on 20 December 1934. The latter's only son, Jean Charles, bears the same title and name.