From the introduction:
The War Horse as a Player Character Originally presented as a Monster in NL01 "Fairies!", the intelligent War Horses, who work with the Crusaders as mounts, are not native to the Fairies world. They are, in fact, the descendants of a group of interstellar explorers who were stranded there after their spaceship was infiltrated by a group of fairies. The War Horses used human slaves to fly and clean their spaceship, and after the fairies seduced the humans, the slaves staged an escape, blasting off in the spaceship and leaving their War Horse masters stranded in the Magic Forest.
Originally published as text in 1994; shortly thereafter published as HTML; published in 2008 as PDF (possibly by a third party).