Daeron I, known as the Young Dragon, was the eighth king to sit the Iron Throne.
Daeron had long felt that the continued independence of Dorne represented unfinished business for the Targaryens. Upon his ascension to the throne he successfully led the conquest of Dorne, uniting all seven kingdoms for the first time.
However, he was unable to hold Dorne and died trying to control an uprising.
“Daeron Targaryen was only fourteen when he conquered Dorne” Jon said. The Young Dragon was one of his heroes.