Reign of Madness
The last of the Targaryens to reign, Aerys II was dubbed the "Mad King" for his bouts of insanity and increasingly violent and unpredictable behavior. After the king brutally executed Lord Rickard Stark and his son Brandon, many houses in the realm rose up against him, under the leadership of Robert Baratheon. Robert and his friend Ned Stark defeated the army of Prince Rhaegar Targaryen -- who had ridden off with Ned's sister Lyanna -- and King Aerys himself was killed when his ally House Lannister betrayed him in his home of King's Landing. Only two Targaryens survived the war, children named Viserys and Daenerys, who were spirited away to the continent of Essos, where they grew up in exile. Robert took the Iron Throne and has ruled Westeros since.