The chief warden of the internment camps, Aedelas Blackmoore, watched over the captive orcs from his prison-stronghold, Durnholde. One orc in particular had always held his interest: the orphaned infant he had found nearly eighteen years before. Blackmoore had raised the young male as a favored slave and named him Thrall. Blackmoore taught the orc about tactics, philosophy, and combat. Thrall was even trained as a gladiator. All the while, the corrupt warden sought to mold the orc into a weapon.

Despite his harsh upbringing, young Thrall grew into a strong, quick-witted orc, and he knew in his heart that a slave's life was not for him. As he grew to maturity, he learned about his people, the orcs, whom he had never met: after their defeat, most of them had been placed in internment camps. Rumor had it that Doomhammer, the orc leader, had escaped from Lordaeron and gone into hiding. Only one rogue clan still operated in secret, trying to evade the watchful eyes of the Alliance.

The resourceful yet inexperienced Thrall decided to escape from Blackmoore's fortress and set off to find others of his kind. During his journeys Thrall visited the internment camps and found his once-mighty race to be strangely cowed and lethargic. Having not found the proud warriors he hoped to discover, Thrall set out to find the last undefeated orc chieftain, Grom Hellscream.

Constantly hunted by the humans, Hellscream nevertheless held onto the Horde's unquenchable will to fight. Aided only by his own devoted Warsong clan, Hellscream continued to wage an underground war against the oppression of his beleaguered people. Unfortunately, Hellscream could never find a way to rouse the captured orcs from their stupor. The impressionable Thrall, inspired by Hellscream's idealism, developed a strong empathy for the Horde and its warrior traditions.

Seeking the truth of his own origins, Thrall traveled north to find the legendary Frostwolf clan. Thrall learned that Gul'dan had exiled the Frostwolves during the early days of the First War. He also discovered that he was the son and heir of the orc hero Durotan, the true chieftain of the Frostwolves who had been murdered in the wilds nearly twenty years before.

Under the tutelage of the venerable shaman Drek'Thar, Thrall studied his people's ancient shamanistic culture, which had been forgotten under Gul'dan's evil rule. Over time, Thrall became a powerful shaman and took his rightful place as chieftain of the exiled Frostwolves. Empowered by the elements themselves and driven to find his destiny, Thrall set off to free the captive clans and heal his race of demonic corruption.

During his travels, Thrall found the aged warchief, Orgrim Doomhammer, who had been living as a hermit for many years. Doomhammer, who had been a close friend of Thrall's father, decided to follow the young, visionary orc and help him free the captive clans. Supported by many of the veteran chieftains, Thrall ultimately succeeded in revitalizing the Horde and giving his people a new spiritual identity.

To symbolize his people's rebirth, Thrall returned to Blackmoore's fortress of Durnholde and put a decisive end to his former master's plans by laying siege to the internment camps. This victory was not without its price: during the liberation of one camp, Doomhammer fell in battle.

Thrall took up Doomhammer's legendary warhammer and donned his black plate-armor to become the new warchief of the Horde. During the following months, Thrall's small but volatile Horde laid waste to the internment camps and stymied the Alliance's best efforts to counter his clever strategies. Encouraged by his best friend and mentor, Grom Hellscream, Thrall worked to ensure that his people would never be slaves again.