An Emperor Dead at Sixteen. A Plague That Killed Millions. An Empire on the Brink of Collapse. In November 251 CE, Gaius Valens Hostilianus Messius Quintus-Augustus of Rome-died after ruling for just four months. He was roughly sixteen years old. His father and brother had been slaughtered weeks earlier at the Battle of Abritus, the first Roman emperors killed in battle by barbarians in over two centuries. Now plague claimed the last surviving son of the Decian dynasty. Most historians have never heard of him. This book tells his story. HOSTILIAN reconstructs the brief, tragic life of Rome's forgotten boy-emperor through meticulous analysis of ancient sources-Ammianus Marcellinus, Cyprian of Carthage, Eutropius, the Historia Augusta, and newly examined archaeological evidence. Drawing on recent scholarship by Kyle Harper, Adrian Goldsworthy, and Peter Heather, this thoroughly researched account places Hostilian's reign within the catastrophic context of the Third Century Crisis (235-284 CE). Between 249 and 251 CE, the Roman world faced simultaneous catastrophes: the Plague of Cyprian killed up to five million people across the empire. Gothic armies sacked major cities including Philippopolis, massacring over 100,000 civilians. The currency collapsed as silver content dropped below 5%. Over fifty men claimed the throne in fifty years, most dying violently within months. Into this apocalyptic moment stepped a teenager who never expected to rule. This account examines: The Battle of Abritus (June 251 CE) where both Emperor Decius and his elder son perished in marshland combat - The mysterious rise of Trebonianus Gallus and his decision to elevate rather than eliminate his predecessor's surviving heir - Daily life in Rome during the pandemic's peak, when 5,000 died daily - The medical evidence about what actually killed Hostilian-plague or poison? - How Christianity gained strength while traditional Roman religion failed to stop mass death Through Hostilian's four-month reign, readers witness the Roman Empire at its absolute nadir. This is not another celebration of imperial glory. This is the story of what happens when every institution fails simultaneously, when even emperors cannot protect themselves from invisible enemies, and when a boy inherits a world that is dying around him. Meticulously sourced and compellingly written, HOSTILIAN recovers a lost voice from antiquity's darkest chapter. Perfect for readers of Mary Beard, Tom Holland, and anyone fascinated by how civilizations survive-or fail to survive-existential crises.