This dissertation examines Greek and Latin letters from the mid-fourth to the mid-fifth century to understand the use of martial imagery in non-military contexts in the later Roman Empire. In a reappraisal of narratives of late antique militarization, I argue that an ethos of quasi-military service reverberated through elite discourse and reinforced the presence of the state in society. Epistolographers imagined bureaucrats as soldiers, dutifully serving the emperor, and represented Christian clerics and ascetics as “soldiers of Christ,” obediently laboring with similar discipline. While this military idiom of state and church service reinforced hierarchical and binary relationships throughout society, churchmen and administrators adopted martial imagery for their own ends, whether to cultivate patronage networks, promote agendas, or criticize rivals. Both bureaucratic and ecclesiastical models of service were contested. Traditionalists questioned the logic of soldierly administrative language, and entrepreneurial bishops, aware of these objections, exploited similarities between bureaucratic and Christian militia to contrast earthly and heavenly service. By taking up an extended form of militarism, writers moved away from traditional modes of social organization, emphasized more distant and abstract hierarchies, and strengthened universalizing rubrics of allegiance.