They were the armed men closest to the Roman emperor. Praetorians guarded palace doors, escorted rulers, marched on campaign and enjoyed pay and privileges beyond those of ordinary legionaries. Their position made them indispensable—and gave them opportunities no other soldiers possessed.

The Praetorian Guard follows the corps from its republican precedents and Augustan foundation to the fortified Castra Praetoria, the ambitions of Sejanus and the violent succession of Caligula and Claudius. It reconstructs recruitment, hierarchy, drill, religion, family life, donatives and the expanding power of the praetorian prefects.

The later chapters place famous scandals in their wider setting: the abandonment of Nero, the murder of Galba, the battles of 69, Domitian's avengers, the killing of Pertinax, the so-called auction of the empire and Septimius Severus's replacement of the old guard. Drawing on ancient historians, inscriptions, coins, sculpture and archaeology, this richly illustrated account explains how the guard could make emperors, why it so often failed to control the empire, and why Constantine finally abolished it in 312.