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This paper blends traditional historiographic techniques with digital mapping technology to explore the relationship between the Roman army under the early empire, military geography, and the nuances of imperial power relations on the frontiers. I argue that by identifying environments in which the Roman army struggled to wage war and by mapping these environments through Geographic Information Systems (G.I.S.) technology, we can use geospatial analysis to better understand Roman policy and provincial resistance on the empire’s periphery.

Previous scholarship on Roman military imperialism has underappreciated how physical geography shaped and constrained frontier arrangements. Debates have focused on the motivations for Roman conquest (Harris, 1979; Eckstein 2006) and the strategies, “grand” or otherwise, by which the empire defended and occupied its territories (Luttwak, 1976; Isaac, 1990). Such discussions center on what Roman Senators and Emperors wanted to do; they have neglected what the military which implemented their decisions could do.

As is the case for all militaries, especially before the industrial revolution, the physical environment limited the Romans’ ability to wage war. This is no mere tactical curiosity, but a crucial explanatory force in any socio-political history of Roman imperialism. After all, military force was (and remains) a crucial tool by which empires exert their will over territory (Mann, 1986; Landers, 2003). As a result, where geography made Roman military intervention impractical or impossible, the empire was forced to accept a shallower level of control over its would-be subjects, or to negotiate power relationships based on factors other than force.

This paper focuses specifically on the challenges which mountainous, rugged terrain posed to Roman force projection and political control. Greco-Roman military literature provides overwhelming evidence for the empire’s discomfort with mountain warfare; combat on broken ground, while possible, was risky and unappealing. Comparative evidence suggests that this environmental challenge was not unique to the Romans. Consider the bloody and largely ineffective attempts by Macedonian, British, Soviet, and NATO armies to pacify the mountains of Afghanistan. Like empires before and after, the Romans struggled to control rough terrain through military force.

Having used a fairly traditional close reading of fairly traditional sources to demonstrate this structural relationship between rugged environments and Roman military control,this paper turns to G.I.S. technology to locate such environments in the ancient world. I argue that data produced through modern, remote-sensing techniques (Jarvis et al., 2008) can be used to reconstruct ancient terrain with reasonable accuracy, while a spatial analysis metric known as the Terrain Roughness Index (Riley et al., 1999) can evaluate the ruggedness of the ancient physical environment on a large scale with substantial precision. By identifying mountainous environments as likely challenges to Roman rule and plotting these environments on a map, this paper produces a geospatial model of imperial control, a tool which allows researchers to integrate space into discussions of Roman imperialism and frontier studies in ways that would be impossible without digital assistance.

This paper concludes with a case-study showing how this methodology can prove beneficial in practice. Using G.I.S. technology to analyze the terrain of 1st century C.E. Judaea provides a valuable lens for understanding Jewish-Roman relations, culminating in the Great Revolt of 66-73 C.E. By applying Terrain Roughness Indexing to the environs of major Jewish population centers, we may better understand the decisions of some of these communities (most notably Jerusalem) to resist Roman authority and of some (most notably Sepphoris, in Galilee) to acquiesce to Roman control. Populations in the plains recognized by long experience that they were readily accessible targets for Roman military force and tended to fold before imperial demands. In the highlands, provincials bargained with and repudiated Roman authorities from a position of relative security, recognizing the military advantages afforded by their rugged surroundings.