The first half of his life he was in exile and in military service of the House of Austria and lived for a long time in Silesia; only in 1697 he and his family were able to return of Montbéliard, and two years later he assumed the government as the last legitimate male member of his dynasty.
His father was George II (5 October 1626 – 1 June 1699), who in 1662 succeeded his older half-brother Leopold Frederick as Duke of Württemberg-Montbéliard; however, in 1676 he was expelled from his domains by the troops of King Louis XIV of France and only was able to return in 1697, two years before his death.
George II was a member of the Imperial Comital and (since 1496) Ducal House of Württemberg in the cadet branch founded in 1617 after the division of the family lands between John Frederick, Duke of Württemberg and his younger brothers, among them Louis Frederick (father of George II), who received the possessions on the left bank of the Rhine (Montbéliard, Riquewihr and Horburg) with full sovereignty.
The eighth and youngest child of Duke George II of Württemberg-Montbéliard by his wife, Countess Anne de Coligny, Leopold Eberhard was born on 21 May 1670 in the city of Montbéliard.
His youth was traumatized by the fact that his family was expelled from their ancestral domains when Leopold Eberhard was just a 6-years-old boy, and only returned to Montbéliard after 22 years of exile at the age of 28.
There he met Anna Sabine Hedwiger, a lady-in-waiting at the court of Oels, and fell in love with her; they married on 1 June 1695 at the town of Rejowiz near Poznań in order to legitimized their newborn child.
Because according to the laws of the House of Württemberg this union was morganatic, the ceremony was secret and completely ignored by Duke George II, who was already prepared a marriage for him with a princess of royal blood.
Since he couldn't count with the support of either his German cousins or neighbors, he turned to King Louis XIV and asked him for the deployment of French troops to quell the uprising.
Married since 1 June 1695 with the Silesian lady-in-waiting Anne Sabine Hedwiger, this union according to the family laws of the House of Württemberg was morganatic; for this, Leopold Eberhard urged the Emperor to give his wife a noble title.
In order to obtain this, he showed proofs that the Hedwiger family had noble origins and served the Empire with loyalty and dedication during generations; even a genealogy was constructed to support the claim.
During his campaigns against the Turks, the prince developed a friendship with Richard Curie, also known as "l'Espérance" (the Hope, a war nickname), Captain of the Imperial army and son of a sergeant of justice in Montbéliard.
Without any care of the mockery of his subjects, Leopold Eberhard lived with his wife and mistresses until 1700, when Anne Sabine, found this situation unbearable, and finally separated from her husband (but without divorcing him) and moved to the castle of Héricourt, where she remained for the rest of her days.
On 10 August 1716, Leopold Eberhard gave to his Sandersleben adoptive children the County of Coligny, jointly with his own biological legally surviving offspring; from them they were called Count/Countess of Sandersleben-Coligny.
The official French recognition of this cession was confirmed on 5 February 1718 in Paris;[5] six months later (15 August), the Duke contracted a second married with Élisabeth Charlotte Curie, sister of Henriette and also another of his mistresses.