The Blood War

The Blood War was an ancient conflict that raged between the fiends of The Nine Hells and the daemons of The Fade. Daemons were chaotic evil while devils and fiends from the Hells were lawful evil. Neutral evil yugoloths played both sides against one another.

History

The Blood War had raged on since the Primal Age, a dark time when the Prime Material Plane had not fully developed yet. The conflict was massive, spanning entire planes of reality, and hosting an almost infinite number of participants.
The main site of the majority of conflicts pertaining the Blood War was Avernus, the first layer of The Nine Hells. Demonic forces sailed the River Styx into the layer by crossing the Blood Rift, binding both realms together and were repelled by diabolic legions that brought reinforcements from the lower layers of the Hells. The conflict, however, often did not remain confined to Avernus, as destructive skirmishes emerged anywhere in the multiverse where demons and devils could gain access to.
The cause of the Blood War was unknown, but most believed it to be a remnant of the great war of Law against Chaos, the powerful struggle of the primal forces that created the world as we know it today. Of course the other fiends had their own notions about the war, colored by their particular alignments and racial propaganda. Some demons and devils seemed to believe that their respective races could actually gain control over the other. However, the most powerful archdukes of the Hells and the most cunning daemon lords of The Fade paid the Blood War little concern, and if entities as ancient and formidable as them seemed unconcerned, then the cause would most likely be a fruitless one...