During the long reign of Alfonso VIII, Castilian bishops were crusaders, castellans, cathedral canons, and collegiate officers, and they served as powerful intermediaries between the pope and the king of Castile. In A Constellation of Authority, Kyle C. Lincoln traces the careers of a septet of these bishops and uses this history to fill in much of what really happened in thirteenth-century Castile. The relationships that local prelates cultivated with Alfonso VIII and the Castilian royal family existed in tension with how they related to the reigning pope. Drawing on diocesan archives,...