Beginning in 1095 and culminating four bloody years later, the First Crusade represented a new kind of warfare: holy, unrestrained, and apocalyptic. In Armies of Heaven, medieval historian Jay Rubenstein tells the story of this cataclysmic event through the eyes of those who witnessed it, emphasizing the fundamental role that apocalyptic thought played in motivating the Crusaders. A thrilling work of military and religious history, Armies of Heaven will revolutionize our understanding of the Crusades.