Blood War

The Blood War is the ongoing and ceaseless conflict between devils and demons. It takes place mostly on the battlefields of Armageddon but occasionally spills out into other planes.

Origins
Before the Concordance, there had been many conflicts between gods and beings of good, evil, and neutrality. However, these conflicts were typically resolved quickly, with one side rising victorious over the other. Lesser gods, demigods, and other powers would commonly rise to power only to be defeated by a competitor. In the end, a balance was always struck.

One of the perpetrators of such conflicts was the chaotic evil god Anarcathus. Unlike most others, he was wholly unwilling to negotiate with his opponents, saw enemies in all others, and seemed to value destruction for its own sake. He sometimes traveled to the Material planes to reap chaos, inspiring armies of mortals to wage dishonorable and meaningless war against one another. Even when victorious, Anarcathus would sometimes destroy his own armies using monstrous avatars and destructive magic.

Finally, the Concordance was struck, with its Second Commandment to seal Anarcathus within the Abyss. For a time this was successful. However, a strange new breed of fiends began spilling out of the Abyss, into the Verge and other planes. They seemed to be creatures of pure chaos and evil, bent on little more than destruction.

It was discovered that Anarcathus, although unable to escape his imprisonment, was able to breach the barriers between the Abyss and the Negative Energy Plane. Using the influx of negative energy, he crafted a new kind of fiend known as a demon. Not bound to the Concordance, the demons were free to leave that plane and invade others.

The War in Armageddon
The demons first spilled out of the Abyss and into the Verge, which was originally part of Hell. The demons quickly conquered that plane, and continued onward to the plane of Armageddon. It was there that the devils were able to hold them.

And then other things happened.