Weaving together evolutionary microbiology, economics, military strategy, ecology, and ancient and modern medicine, author Rosen tells of history's first pandemic--a plague seven centuries before the Black Death that killed tens of millions, devastated the empires of Persia and Rome, left victims from Ireland to Iraq, and opened the way for the armies of Islam. Emperor Justinian had reunified Rome's fractured empire by defeating the Goths and Vandals who had separated Italy, Spain, and North Africa from imperial rule. In his capital at Constantinople he built the world's most beautiful building, married its most powerful empress, and wrote its most enduring legal code, seemingly restoring Rome's fortunes. Then, in the summer of 542, he encountered a flea. The ensuing outbreak of bubonic plague killed five thousand people a day in Constantinople and nearly killed Justinian himself, bringing about one of the great hinge moments in history.--From publisher description.