In the eleventh century, a vast Christian army, summoned to holy war by the pope, rampaged through the Muslim world of the eastern Mediterranean, seizing possession of Jerusalem, a city revered by both faiths. Over the two hundred years that followed this First Crusade, Islam and the West fought for dominion of the Holy Land, clashing in a succession of chillingly brutal wars, both firm in the belief that they were at God's work. For the first time, this book tells the story of this epic struggle from the perspective of both Christians and Muslims, reconstructing the experiences and attitudes of those on either side of the conflict. Mixing pulsing narrative and piercing insight, it exposes the full horror, passion and barbaric grandeur of the crusading era. One of the world's foremost authorities on the subject, Thomas Asbridge offers a vivid and penetrating history of the crusades, setting a new standard for modern scholarship. Drawing upon painstaking original research and an intimate knowledge of the Near East, he uncovers what drove Muslims and Christians alike to embrace the ideals of jihad and crusade, revealing how these holy wars reshaped the medieval world and why they continue to echo in human memory to this day.