From publisher blurb:
Amidst the blood and carnage of battle, the barrier between the world of the living and the world of the dead grows thin, and, occasionally, something slips through. Although usually dismissed as fantasy or fairy tale, history contains numerous stories of violent warriors, decapitated in battle, who return from the dead to terrorize the living. The ancient Irish called these malevolent spirits dullahan, but in English they are generally called headless horsemen.
This book presents the history of these rare and dangerous undead warriors, explaining how and why they were created, describing their strengths and limitations, and finally revealing how they can be defeated. It also examines the best-documented encounters with these spirits, including the most famous and enduring manifestation, the Headless Horseman of Sleepy Hollow.