By Demons Be Driven is chapter 8 of the orc campaign, The Invasion of Kalimdor. This is the final mission in the orc campaign. It also marks the first time in which the orcs and the humans sided with each other against a common foe.
- 1 Centaur Khans
- 2 Centaur Archers
- 4 Centaur Drudges
- 2 Centaur Impalers
- 3 Centaur Outrunners
- 3 Centaur Sorcerers
- 5 Harpy Scouts
- 1 Harpy Storm-hag
- 4 Lightining Lizards
- 1 Storm Wyrm
Thrall, Cairne Bloodhoof, and Jaina Proudmoore met in preparation for their joint assault on the corrupted Warsong Clan. Thrall was very uneasy about all of this, as not only would he be fighting his own people, but he would be working with his old enemies too. Jaina gave Thrall a magical Soul Gem which would allow him to capture Grom Hellscream without harming him. Once Hellscream was subdued, they would be able to purge him of the demonic corruption. Jaina then left to take charge of her own forces nearby. Thrall confided in Cairne that he feared if Grom couldn't be saved, then the orcish race may be doomed.
The battle soon began as Horde and Alliance soldiers clashed with the Warsong clan. The Warsong orcs did not give ground easily. The demonic corruption had given them enhanced strength and endurance. It had also stripped them of any qualms about killing their own brethren. Nevertheless, while Alliance troops held the Warsong advance, Thrall's forces attacked and pushed their way through, rescuing a number of captive Trolls along the way.
While the battle raged on, the skies suddenly turned red and caught fire. Infernals came crashing down onto the battlefield inflicting heavy damage on the Alliance and Horde forces. The demonic invasion of Kalimdor had begun. Despite this, Thrall fought on determined to reach Hellscream at all cost.
After defeating Hellscream's cadre of Doomguards, Felhounds, and orcish Warlocks, Thrall confronted Grom himself. Thrall pleaded with Grom to surrender and come with him. Grom refused and declared that Mannoroth was the master of the orcs now. Thrall didn't understand what Grom was talking about. Grom then revealed that the Legion had corrupted the orcs because they had been allowed to do so. Back on Draenor Grom and the other Chieftains willingly drank Mannoroth's blood thus knowingly condemning themselves to be slaves of the Burning Legion. Thrall was enraged by this revelation and attacked Hellscream. After a desperate struggle, Thrall managed to regain control of himself and used Jaina's Soul Gem to capture Grom. He then returned to Jaina.
Thrall's shamans and Jaina's priests successfully purged Grom of the demonic influence. Now freed of the demons' control, Grom was ashamed of his recklessness and tried to apologize to Thrall. Thrall, however, was in no mood for apologies. He needed Grom to help him save their people. Grom told him that Mannoroth was waiting for them in a nearby canyon. Thrall replied that they had best go and confront the demon lord, as he didn't want to "keep the bastard waiting."
- "By Demons Be Driven" is a song by Pantera of their 1992 album Vulgar Display Of Power.