Bruenor was but a non-bearded dwarven youth when gray dwarves, with the aid of a shadow dragon named Shimmergloom, attacked Mithral Hall and drove out his clan. Its surviving members were scattered, with a main remnant, containing Bruenor, escaping to Icewind Dale. Bruenor rose to leadership of the hundred or so dwarves that remained, and eked out a profitable partnership with the human settlement Ten-Towns, though the dwarf treasured his few memories of his home and vowed to return there. Bruenor tricked Drizzt into vowing to help him find it. After finding it, Bruenor and his companions took back Mithral Hall with the aid of Citadel Adbar, Longsaddle, and Nesmé. After it was reclaimed, the Clan Battlehammer dwarves moved from Icewind Dale back to their ancestral home of Mithral Hall. Dwarves from other strongholds immigrated to Mithral Hall, as well. Bruenor then became the eighth king and later the tenth king after his ancestor, the first king Gandalug, was recrowned and later died.
After that, Matron Baenre of Menzoberranzan's first house used the city's hatred for Drizzt Do'Urden to mount a war effort against Mithral Hall. Publicly vowing to send Drizzt to the Spider Queen, her main motivation was a rout of the dwarven fortress. The battle for Mithral Hall was incredibly pitched, with the day's light ultimately crippling the light-sensitive drow soldiers. Drizzt and his companions fought and killed Matron Baenre and her party, forcing the remaining drow attackers to retreat.
Several years later, an orc king named Obould massed a huge army of orcs, goblins, trolls, and frost giants together, intending to take Mithral Hall for himself. Bruenor and his friends were forced to hold off a massive army, but managed to seal themselves into the fortress where they could wait out the orcs.