Rome and the Enemy: Imperial Strategy in the Principate (1999) by Susan P. Mattern

By the end of the second century AD, Rome held political sway over much of the civilized world. In some places, such as northern Britain or eastern Europe, the limits of the empire were clearly demarcated by defensive walls or natural boundaries like rivers. In most places, however, Roman authority simply stretched on amorphously into the distance. How did this far-flung, multifaceted, yet coherent empire come into being? Was there any logical policy that welded everything together? Specifically, what does classical literature tells us about Roman views on war and peace? That is the question that Susan Mattern seeks to answer in “Rome and the Enemy: Imperial Strategy in the Principate.”

The Roman Empire may have been vast and complicated, but the Roman national security and foreign policy apparatus were not. There was no national security council for making strategic policy decisions; no intelligence agencies for assessing threats; there weren’t even reliable maps for understanding the geography of military theaters of operations. “They pictured a schematic, oval-shaped world, formed by zones of bitter frost and scorching heat, surrounded by the ancient, impassable ocean and inhabited at its edged by primitive, exotic, sometimes mythical people.” Those from the north were thought to be tougher and more belligerent, stereotyped in the literary sources as “nomadic, fierce, cruel, treacherous, disorganized in battle, drunken, greedy for plunder, lacking in discipline.” Meanwhile, those from milder climates were viewed as effete, docile, and more civilized. Beyond was terra incognita, an “outer limit…alien and unknown but within reach.”

Mattern stresses that all decision-making authority was vested in one man, the emperor, who might rely on a select inner circle of friends when making critical decisions of war and peace. He personally directed an army of 28 legions numbering perhaps 150,000 well-trained soldiers with a similar number of auxiliary troops supplied by the empire’s allies. “The army of empire, then, was not especially large,” Mattern writes, “and warfare on two fronts posed a dangerous problem.” So what then was the emperor’s strategy for maintaining, and possibly growing, the empire with such limited resources, both manpower and imperial infrastructure? Mattern claims that for the Romans everything came down to image – “the image of the force it could wield and on its apparent willingness to use that force at whatever cost.” Thus, the author maintains, Roman policy worked mainly on a psychological level; “it was a strategy of deterrence by terror.”

“As a state, Romans behaved like Homeric heroes, Mafia gangsters, or individuals in any society based on violent competition for honor and respect.” Deference from the enemy was a critical goal of Roman foreign policy. They held a close link between Roman dignity – or the appearance of greatness – and its security. “Any military defeat, breach of treaty, or revolt should be paid vigorously and aggressively with invasion, conquest, and humiliation,” she writes. Policy, therefore, was built around the need to repress what the Romans called “superbia,” arrogance or brazen effrontery by the enemy; to avenge “iniuriae,” any perceived injustice committed by the enemy; and above all the need to maintain “decus,” or what we may today call “saving face.” “It was on these things that, as they believed, their security depended; it was for these things that they fought.”

Personal glory and fortune may also come from military conquest, but they were not sufficiently “just” causes for waging unprovoked wars of conquest. Mattern notes that the pace of conquest under the Principate slowed compared to that of the late Republic mainly because the emperor needed to control the prestige associated with victory. There could only be one major campaign at any one time because all military glory must redound to one man, the emperor. Greed and glory, therefore, were plausible, though not exactly respectable, causes for war. “[Roman] policy depended on perceived and acknowledged military superiority, on the terror and awe of the enemy; and if this imaged was challenged by invasion, defeat, or revolt, the Romans reasserted it with the maximum possible punishment and ferocity.”

Mattern’s thesis tracks closely with that elucidated by Edward Luttwak in “The Grand Strategy of the Roman Empire: From the First Century A.D. to the Third,” particularly what he calls the first phase of empire, the Julio-Claudian system of “Client States and Mobile Armies” (from Augustus to Nero, 31BC to 68AD) that was marked by a thoughtful and rather nuanced economy of force in a hegemonic empire system.

In closing, Mattern patches together a plausible story for how the Roman Empire of the first and second centuries was managed and defended. “Rome and the Enemy” is a short, but dense monograph that may be a bit too detailed for the typical lay reader. For anyone with a keen interest in the Roman Empire or in imperial strategy, however, it is “must read.”