A blacksmith's bastard of Dragonstone, tall and huge, with hands strong enough to twist steel bars and a warhammer to swing with them. He could neither read nor write. When Prince Jacaerys Velaryon called for dragonseeds in 129 AC, Hugh went into the smoking caverns of the Dragonmont and came out on Vermithor, the Old King's own mount, riderless since Jaehaerys died. He fought well for the blacks in the Battle of the Gullet, and it was after that he began styling himself Hugh Hammer. Prince Daemon would have wed him to the late Lord Rosby's daughter, but Queen Rhaenyra refused and gave him a knighthood and lands on Driftmark instead, and refused again when Daemon proposed giving him Casterly Rock. Mushroom says he beat one of the queen's knights to death in the Street of Silk over a maiden.
In 130 AC he and Ulf White were sent to hold Tumbleton against Lord Ormund Hightower's host, and in the middle of the First Battle of Tumbleton the pair of them turned their dragons on the men they had come to defend. The realm named them the Two Betrayers for it. Hugh had no intention of stopping at a lordship: the soldiery had a prophecy that a new king would rise when a hammer fell upon a dragon, and Hugh meant to be that king. Prince Daeron threw wine in his face when he said so, and Hugh threatened to beat the boy bloody. He wore a crown of black iron the next day; Ser Roger Corne knocked it off his head and told him a crown does not make a man a king, so Hugh nailed three horseshoes to Roger's skull, and the brawl that followed left three dead and twelve wounded. The Caltrops were still laying their plot to murder him when the Second Battle of Tumbleton broke over the camp. Ser Jon Roxton found him arming and opened him with the Valyrian blade Orphan-Maker, and Hugh's own men cut Roxton down in turn, after he slipped, it is said, on one of Hugh's entrails.