In Sea of Faith, O'Shea chronicles both the meeting of minds and the collisions of armies that marked the interaction of Cross and Crescent in the Middle Ages-the better to understand their apparently intractable conflict today. For all the great and everlasting moments of cultural interchange and tolerance-in Cordoba, Palermo, Constantinople-the ultimate "geography of belief " was decided on the battlefield. O'Shea vividly recounts seven pivotal battles between the forces of Christianity and Islam that shaped the Mediterranean world-from the loss of the Christian Middle East to the Muslims at Yarmuk (Turkey) in 636 to the stemming of the seemingly unstoppable Ottoman tide at Malta in 1565. In between, the battles raged round the Mediterranean, from Poitiers in France and Hattin in the Holy Land during the height of the Crusades, to the famed contest for Constantinople in 1453 that signaled the end of Byzantium. As much as the armies were motivated by belief, their exploits were inspired by leaders such as Charles Martel, Saladin, and Mehmet II, whose stirring feats were sometimes accompanied by unexpected changes of heart.