House Tarly of Horn Hill is an old and martial Reach house sworn to Highgarden. They claim descent from Garth Greenhand through his son Herndon of the Horn, and they bear the ancestral Valyrian-steel greatsword Heartsbane, which has been borne by the lord of Horn Hill for five hundred years.
Lord Randyll Tarly is reckoned by many, not least himself, to be the finest battle commander in the Reach, the only field captain to have bested Robert Baratheon in open battle during the Rebellion. His firstborn son, Samwell, is by his father's measure too soft for sword or saddle; rather than name a fat boy his heir, Lord Randyll sends him in cold half-disguise to take the black at the Wall.