Being in the Main a Roleplaying Supplement of Darkness and Deviltrie in an Age of Reason
From the introduction:
It's 1603, England. It's a time when the glorious reign of Good Queen Bess, friend to faerie, nears its end and the future is uncertain for the realm. In this world, over a thousand years ago, Arthur really did fight his bastard son on the field, blood against blood, and the faerie hosts were accomplice to it all. Merlin was the greatest of the druids and the architect of Arthur's reign but he had passed on, and across all of Europe the fey were cast out and back into their own hidden lands as mortals learned they were not gods, and the Church branded them demons. Except for the dwarves, the trolls, and the goblins, who had given up their faerie powers due to greed, ignorance and desperation respectively, the sidhe and their darker reflections retreated. Magic, codified and structured into ritual and ceremony, was almost lost as civilization and learning were crushed underfoot by barbarian invasions, the pettiness of popes, and the fear of kings. It would be a long time before the light would return.