While no Latin ars of warfare survives from the early Empire, its development can be reconstructed with the help of Frontinus’ Stratagemata (Domitianic), a collection of military stratagems composed as a pendant to his (now lost) treatise on the scientia rei militaris, and with Onasander’s Stratêgikos (c. AD 49–58), a Greek theoretical treatment of generalship dedicated to a Roman general. Onasander’s treatise embodies a paradigm of specialized knowledge that puts precepts into an explanatory relationship with universal (natural) first principles, much in the spirit of the artes. This approach to the art of war was popular but seems also to have been fiercely criticized at Rome. Frontinus’ Strategemata responds to this criticism by eschewing generalized precepts and offering instead exemplary historical anecdotes for contemplation and imitation. The Roman art of war thus reveals significant generic diversification in reaction to pressures internal and external to the scientific culture of the artes.