Louis Joseph, Dauphin of France
Louis Joseph de France was the second child and elder son of king Louis XVI of France and Marie Antoinette. As son of a king of France, he was a Fils de France , and as the eldest son and heir apparent, he was Dauphin of France,
Louis Joseph Xavier Franois de France was born at the Palace of Versailles onOctober 1781. He was the long awaited Dauphin. His elder sister, Marie Thrse Charlotte, Madame Royale, was not allowed to succeed to the throne due to the Salic Law. The birth of Louis Joseph at that point ruined his uncles hopes of becoming the king.
Source: Wikipedia