The volume traces the effect of the crusades on the Eastern Roman state, showing how early Western intervention recovered territory even as later expeditions and the diversion of forces culminated in the sack and partition of the capital. It follows the rise of rival Greek courts, destructive civil wars, and mounting pressure from Mongol and Turkish powers that eroded imperial authority. It examines the careers of powerful conquerors and the shifting relations between Latin and Orthodox Christianity, including efforts at union and the persistence of schism. The account concludes with the final Ottoman conquest that ends the Eastern empire and reflections on the papal state and the ruins of ancient Rome.