When Christian armies seized Jerusalem in 1099, it opened an era of conflict with Islam that sparked the Crusades and has continued sporadically through the present day. Expanding the timeframe, the author of Magna Carta and The Plantagenets looks to the roots of Christian-Muslim relations in the eighth century and widens the geographical focus to Spain, North Africa, southern France, and the Baltic states. By viewing the Crusades through the stories of individual journeys, Dan Jones illuminates the perspective of popes and kings, but also Arab-Sicilian poets, Byzantine princesses, Sunni scholars, Shi'ite viziers, Mamluk slave soldiers, Mongol chieftains, and barefoot friars.