Tartarus appears in Dawn of War the first game of the series. The first mission in Dawn of War is Planet Fall. The planet you go to is Tartarus. The first factions to appear on Tartarus is the Imperial Guard and the Orks. The Imperial Guard were trying to protected the planet from the Orks. But what they were trying to accomplish was not working. The Blood Ravens 3rd company come along to help the Imperium. The first lot of Orks get wiped out but there are still more Orks on the planet. Captain Gabriel Angelos takes care of the civilians and the wounded by ordering evacuation ships to come and get the civilians.
Tartarus was besieged by the Orks. Five different Factions fought on the planet Tartarus. Orks, Eldar, Chaos Marines and the Space Marines. Leaving nothing but dirt and destroyed buildings and concret for miles. Like you see in Dawn of War the first mission Planet Fall.