"Louis, Dauphin of France (4 September 1729 – 20 December 1765) was the elder and only surviving son of King Louis XV of France and his ...
wife, Queen Marie Leszczyńska. He had a younger brother, Philippe, who died as a toddler. As a son of the king, Louis was a fils de France. As heir apparent, he became Dauphin of France. However, he died before ascending the throne. Three of his sons became kings of France: Louis XVI (reign in 1774–1792), Louis XVIII (1814–1815, again in 1815–1824) and Charles X (1824–1830), a feat only shared - in French royalty - by kings Henry II and Philippe IV." - (en.wikipedia.org 03.10.2020)