Limitanei, comitatenses, and defence in depth

The late Roman army distinguished mobile comitatenses from limitanei assigned to provinces, cities, and frontier positions, though units could move between categories. Land grants and lower legal status led some historians to dismiss the limitanei as part-time soldier-farmers. The book counters that property ownership did not make a soldier an amateur and points to siege defence, training requirements, valued hereditary service, and recorded battlefield performance. In reconquered Africa, frontier troops were expected to delay an invasion while mobile forces assembled as a reserve, a defence-in-depth system that required both layers to remain effective.