Balaer Empire did not like that ever since the Age of Descent when they first appearing, the Tieflings started encroaching on their territory and building settlements that would not be under their rule.
Remong The Great decided to exterminate the Tieflings from Baal and assembled a force 20,000 men strong consisting mostly of Orcs and an occasional Dragonborn.
Part of the conflict from 497 AD - 499 AD was more of a massacre from the side of the Balaer Empire and running and hiding from the side of the Tieflings.
The situation changed drastically in 499 AD when during an assault of Balaer legion of 5,000 soldiers on 1,000 straggling Tieflings, seemingly out of nowhere, a giant wooden golem joined the fight on the side of the Tieflings.
After the battle was over, her secured a safe passage for the remaining Tieflings off Baal.