His family claimed ancestry from the reigning Dukes of Brittany[1] and at the French court were allowed the rank of Foreign Prince.

At the time, it was suspected that his younger brother Armand Gaston Maximilien de Rohan was in fact fathered by Louis XIV.

His grandson Charles, Prince of Soubise, was born in 1710 and after the death of his parents, was raised by Hercule Mériadec himself to become a man of the court.

Charles was later a great friend of Louis XV and the great-grandfather of the murdered Duke of Enghien through his eldest daughter Charlotte.

Hercule Mériadec was responsible for some interior décor at the Hôtel de Soubise engaging Germain Boffrand in the process.