Complex sentence: Because of the latter, Louis XV of France took a great personal interest in her marriage prospects and it was (Jules) Hercule Mériadec de Rohan, Duke of Montbazon, Prince of Guéméné.
Split into simpler sentences: Because of the latter, Louis XV of France took a great personal interest in her marriage prospects. Eventually, she married Jules Hercule Mériadec de Rohan, Duke of Montbazon, Prince of Guéméné.