This work investigates the historical role, organizational structure, and tactical function of the Roman imperial horse guards, known as the equites singulares augusti. Michael P. Speidel, a recognized authority on Roman military history, utilizes epigraphic evidence, archaeological findings, and classical texts to reconstruct the lives of these elite soldiers. The book argues that these guards served as both a personal security detail for the emperor and a vital political instrument within the Roman power structure. By analyzing military diplomas and tombstone inscriptions, Speidel provides a comprehensive framework for understanding the integration of provincial cavalry into the heart of the Roman administration.

Historians and military scholars frequently cite this text as a foundational resource for understanding the specialized units of the Roman imperial guard. Readers often note the academic density of the prose, which relies heavily on technical analysis of inscriptions and historical records.