Daeron I Targaryen, the fourth of his name to sit the Iron Throne, came to the crown in 157 AC a boy of fourteen, and at once turned his gaze south to the one kingdom his forebears had never brought to heel. Aegon the Conqueror himself had failed to master Dorne, and the First Dornish War had ended in fire and grief; yet the Young Dragon judged that where dragons had failed, a bold captain and a clever plan might yet succeed. He is said to have devised his whole campaign from a book of his own composition, later famed as The Conquest of Dorne, and he divided his host to strike the Dornish by three roads at once.
The main strength of the realm Daeron led himself down the Prince's Pass, while a second column forced the Boneway, and Lord Alyn Velaryon, the sea captain men called Oakenfist, brought the royal fleet against the Dornish coast. The Dornishmen, who had bled the Targaryens for a generation with ambush and raid, could not everywhere hold against so many at once, and the proud houses of the desert, Yronwood of the Boneway and Fowler of the Prince's Pass among them, were beaten in the mountains. Within a year the Young Dragon stood before Sunspear, and the Prince of Dorne bent the knee. For the first time since the coming of the Rhoynar, Dorne answered to the Iron Throne.
The victory was dearly bought and would prove dearly kept. Ten thousand men, it is written, died in the conquest of Dorne, and among the fallen was Rickon Stark, heir to Winterfell, a wound the north would long remember. Daeron entrusted the government of the conquered land to Lord Lyonel Tyrell and returned to King's Landing in triumph, there to be hailed as the greatest conqueror since Aegon himself. But a land taken in a single summer is not so easily held, and the peace the Young Dragon imposed was a peace of garrisons and hostages, resented in every holdfast from the Greenblood to the Red Mountains.