The only son of
Emmanuel Thomas, Count of Soissons (a member of the
House of Savoy-Carignano), and
Princess Maria Theresia of Liechtenstein,
Duchess of Troppau, he succeeded his father on his death in 1729, while remaining his mother's
heir apparent and being often also styled "Duke of Troppau". In the same year 1729, the
King of Sardinia Victor Amadeus II granted him the title of knight of the
Supreme Order of the Most Holy Annunciation, the highest Savoy distinction. In 1731, at the instigation of his grand-uncle,
Prince Eugene of Savoy, a famous general and eminent personality in the imperial court, he was made, like his father before him, knight of the
Order of the Golden Fleece by the
Emperor Charles VI. With the aim of establishing a second
Savoy state in central Italy, Prince Eugene of Savoy, particularly attached to his grand-nephew, who was his last living male heir, requested for him the hand of
Maria Teresa Cybo-Malaspina,
Duchess of Massa and Princess of Carrara, obtaining the approval of
Emperor Charles VI and the
King of Sardinia,
Charles Emmanuel III, whom he looked to as the head of the extended House of Savoy. The duchess was then only seven years old and was under the regency of her mother . Matrimonial agreements were signed in Vienna, where the prince resided, on 2 May 1732, and, in the month of October, the eighteen-year-old betrothed visited Massa to pay homage to his little fiancée and future mother-in-law. The marriage, however, could not take place due to the young count's premature death in
Mannheim, where he was serving the emperor in the military, on 23 November 1734. Maria Teresa would later be married to Ercole Rinaldo d'Este, heir of the
duchy of Modena and Reggio (and future duke under the name
Ercole III). With Eugene Jean's death, the title "Count of Soissons" became extinct and reverted to the French crown. The huge inheritance of Prince Eugene, who died intestate two years later, fell to his closest surviving relative, Eugene Jean's aunt,
Anna Victoria of Savoy. In 1772, upon the death of Eugene Jean's mother, the duchy of Troppau returned to the possession of the
princes of Liechtenstein, in the person of
Franz Joseph I. == Ancestry ==