So you might have read it and wondered what it is. Or maybe you’ve already guessed. But the Unseen War is the conflict between the Divine and the Fallen. There was no official start to the Unseen War, just the aftershock of the Shattering War. When the Fallen were escaped to the mortal plane and were trapped here, their numbers were few and their powers weak. They couldn’t afford to be noticed by the mortal population as a whole. The Divine no longer considered the Fallen a threat and so withdrew from mortal sight.
No one can say for certain when the Unseen War started. Many Fallen right after their exile began to rebuild their power base, tempting mortals into their service. Eventually, through the ingenuity of mortals, they learned how to pull spirits from other planes of existence into the prime plane, binding them to mortal hosts.
After the Shattering War many Fallen began to question their reason for being here and remembering the promise of their Creator schemed to find a way to trick humanity into destroying itself so that the Creator would return.