Dauphin

Coronet of the Dauphin

The title of the eldest son of the King of France or the heir apparent to the throne under the old monarchy.

The title of Dauphin assumed by the eldest son and heir to the crown of France, originated in the ninth century Dauphins of Viennois, sovereigns of the province of Dauphiné in France, who had assumed the dolphin for their arms. The last of those princes, Humbert II, Seigneur de Vienne, dying without issue, bequeathed  his dominions as an apanage to the crown of France, upon condition that the eldest son always bore the title Dauphin of Viennois, and would ever bear a dauphin (Old Fr. daulphin).