BMCR 2018.12.21

Protecting the Roman Empire: Fortlets, Frontiers, and the Quest for Post-Conquest Security

, Protecting the Roman Empire: Fortlets, Frontiers, and the Quest for Post-Conquest Security. Cambridge: Cambridge University Press, 2018. xiv, 251. ISBN 9781108421553. £75.00.


Borders and security dominate contemporary political conversations, particularly in the United States, Britain, and Europe. The continued engagement of international military forces in Afghanistan, Syria, Yemen, and elsewhere also drives the development of better counter-insurgency methods. Such concerns, while clearly shaped by their modern contexts, are nothing new. In their pursuit of post-conquest security (or pax, as they might have called it), the soldiers and administrators of the Roman Empire deployed an array of measures to control peoples and landscapes. Military installations along roads, rivers, and frontiers were some of the most visible means in the pursuit of security. The archaeological remains of such outposts have provided generations of scholars the opportunity to assess Rome’s grand strategy (or lack thereof), imperial ideology, or flexible pragmatism in maintaining control of the Mediterranean world.

Protecting the Roman Empire, a revised and expanded version of Symonds’s 2008 Oxford D.Phil. thesis, seeks to add to the debates surrounding Roman imperial frontiers and provincial security by focusing on the networks of fortlets (also known as praesidia or milecastles) and towers (turrets or burgi), collectively called “outposts” by him, in northwest Europe (modern Britain, the Netherlands, Germany, France, and Switzerland) in the first to fourth centuries CE. Within this scope, Symonds argues that freestanding and frontier outposts were critical in consolidating Roman control of communities and borders and in counteracting small-scale security threats, such as bandits, insurgents, or raiders. Basing his analysis largely on the placement of fortlets and towers on roads, rivers, coastlines, and linear frontiers, Symonds also uses documents from praesidia on the roads of the Eastern Desert of Egypt to “flesh out the archaeological evidence elsewhere” (182), thereby providing additional insight into the everyday struggles of soldiers in the Roman military to establish security. Symonds’s book attempts to shift the conversation back to what he considers was the fundamental purpose of outposts rather than exploring the economic, social, or cultural dynamics of the frontiers.1 Where his book stands out is its much-needed focus on fortlets, an often overlooked structure crucial to Roman control on frontiers and within newly conquered provinces.

The introduction outlines Symonds’s main arguments, defines “fortlet” and “tower,” discusses his method of interpretation of northwestern European archaeological evidence and Egyptian documents, and provides a depiction of everyday life for outpost soldiers who “worked hard and played hard” (30). Unlike the generally standardized playing-card design of fortresses (for legions) and forts (for auxiliary units), the design of fortlets was much more flexible, tailored to the duties expected of the small, frequently rotated garrisons of soldiers stationed there. Symonds settles on Frere and St Joseph’s definition of fortlet, namely a small military site lacking an administrative headquarters building ( principia). He divides his analysis into two general groupings: frontier fortlets (formal border systems) and freestanding fortlets (riverbanks, coastlines, and roads). His method is to see the presence or absence of outposts as a barometer for the local security situation (11). The rather short life of many fortlets, particularly freestanding ones, suggests, he argues, that they were relatively successful in providing the needed security against small threats. His overview of everyday life of fortlet soldiers, derived largely from Egyptian documents, provides a much needed account of individual experiences, yet he engages with the Egyptian evidence only sporadically in later chapters, relying more on his method of argument based on the placement of outposts and the surrounding topography.

Part 1 “Consolidating Conquest” traces the “rapid proliferation of outposts” on waterways and highways in the first and second centuries CE as a sign of the increasing Roman focus on consolidating territorial gain rather than pursuing offensive operations (34).

Chapter 2 “Waterways” focuses on case studies from the Lower Rhine (although without a map), the Raetian Danube, and the Exmoor Coast in Britain overlooking the Bristol Channel. Themes explored include the development of the U-shaped building plan, religious practices, the question of self-sufficiency of fortlets in relation to military supply networks, the role of fortlets as a means of coastal control rather than as signaling stations, and the adoption and adaptation of local architecture for fortlet design.

Chapter 3 “Highways” assesses the differences in the distribution of outposts along roads in Germany, Wales, the Gask Ridge (east Scotland), and Antonine southwest Scotland (especially in and around Nithsdale and Annandale). Topics discussed include the development of the “fort-fortlet-fort pattern of control,” the importance of rapid communication, the possibility of extramural settlements and intramural dwelling of dependents, the impact of human geography on outpost use, and the various types of defenses used. Characterizing the road fortlet garrisons as the “Swiss army knives of outpost systems,” Symonds argues that fortlets were established largely for security purposes rather than for supporting trade. He notes that the difference in numbers and locations of road fortlets in Britain and Germany seem to have reflected the perceived threat of the regions, shaped by differing population densities (90-91).

Part 2 “Border Control” seeks to establish how similar or different the artificial land frontiers of northwest Europe (Hadrian’s Wall, the Antonine Wall, the Upper German and Raetian limites) were from each other as well as their purpose. Factors such as physical geography, pre-existing military deployment patterns, and the numbers and attitude of the indigenous population all shaped the nature of these frontier installations.

Chapter 4 “Hadrian’s Wall” challenges attempts to see Hadrian’s new linear frontier as a way to regulate peaceful movement of people or as a symbolic reflection of Roman power.2 Rather, Symonds posits that the wall served as “an effective anti-raiding shield” designed to spot and stop small-scale incursions (115). Tracing the convoluted construction process (including the “fort decision”), Symonds rightly characterizes Hadrian’s Wall as a “radical innovation” from previous uses of fortlets (108), in which Hadrian “stubbornly pursued an ordered, intellectual solution to border control…an absolute break with preceding fortlet use…[with] such casual disregard for local context” (131).

Chapter 5 “The Antonine Wall” argues that the Romans learned from their experience with Hadrian’s Wall and, instead of simply copying what they did before (as posited by Gillam), they instead tailored the new frontier system to the physical and human geography of the region. Fortlets on the Antonine Wall were “not regurgitated without revision” but were shaped to the local needs (142). Such flexibility allowed for manpower and resource savings. While more efficient, though, the Antonine Wall ultimately failed because the local population did not buy into the Roman project.

Chapter 6 “The Upper German and Raetian limites ” explores the “far more dynamic and responsive” frontier system and its “Jekyll and Hyde character” due to its mix of outposts shaped by local physical and human geography as well as outposts that created long artificial lines (154, 173).

Part 3 “Provincial Collapse” traces the placement and purpose of outposts in the third and fourth centuries in areas not previously garrisoned. Flexible fortlets became more common in this period, as the “act of hubris” and “luxury” of the one-size-fits-all classic fort fell out of use due to the “increased pragmatism” and “heightened sensitivity to local context” of Roman defense structures (211, 225). Rather than subscribing to Luttwak’s “defense in depth” model, Symonds sees late Roman fortlets and towers as playing largely the same role as earlier outposts in countering low-intensity security threats (179).

Chapter 7 “Late Highways” focuses on road outposts in the hinterland of Cologne, the Danube-Iller-Rhine limes, and the Stainmore pass between York and Carlisle, tracing how late fortlets were increasingly shaped to the local terrain.

Chapter 8 “Late Waterways” considers the retrenchment of border defenses along the waterways and coastlines of the Rhine and the Yorkshire “signal stations” (rather, in his view, fortlets meant to stop small coastal raids).

In his conclusion, Symonds emphasizes the flexible utility of fortlets and towers, arguing that they were critical to achieving Roman dominance where actively needed. In his view, the quantity and location of outposts reflect how stable a region was as well as the costs of security for that region. Given their often short occupation, he believes that outposts were very effective in stopping small scale security issues without angering the local population (219-20). Ultimately the “flexible, pragmatic, and informal approach” won out over the more regimented approach of Hadrian’s Wall. Symonds closes with a modest comparison to modern counterinsurgency measures and the small wars of colonial powers.3

Symonds’s method of analysis largely relies on looking at the physical and human landscape surrounding the fortlet or tower and deducing its purpose from a security-centric perspective. He shows little regard for other possible interpretations, particularly the support of trade or the symbolic significance of these structures as indices of Roman power. To what extent soldiers engaged in “policing” rather than suppressing insurgents or deterring bandits should also have been considered.4 The argument based on good old fashioned Roman “pragmatism” always strikes me as somewhat unsatisfactory, although his corrective for the role of coastal fortlets is more probable than them simply acting as “signal stations.” In his thematic asides, though, he points to other areas for further research, such as the role of soldiers’ families and dependents at fortlets and the religious and cultural practices found there. While it’s understandable why he limits his scope to the northwest provinces, more comparison with the use of outposts elsewhere in the Roman Empire (other than his brief mention of Egypt) would have shown how unusual or typical the patterns were. Future scholars should use this as a starting point for a wider study of fortlets across the empire.

An engaging prose style, clear organization, useful info boxes, an excellent topical index, and numerous maps complete a generally successful book. Still, the provided photos of fortlet locations do not add much to the argument and are often difficult to interpret, while an additional index of sources would have been useful. An appendix with a complete listing of all fortlets in northwest Europe is also sadly missing. The text is largely error-free, although an unfortunate typo on the dustjacket summary is somewhat misleading. 5

This book provides an excellent introduction to fortlets and their outpost networks in northwest Europe, tracing their impact on the provincial and frontier security of the Roman Empire. It should appeal not only to frontier specialists but also to anyone interested in Roman military studies and strategy.


1. For a recent overview on the frontiers, see D. Breeze, The Frontiers of Imperial Rome (Barnsley: Pen & Sword Military, 2011); Breeze is thanked in Symonds’s acknowledgements. For a critical review of recent trends in frontier studies, see BMCR 2012.01.31.

2. Starting especially with C. R. Whittaker, Frontiers of the Roman Empire. A Social and Economic Study (Baltimore: The Johns Hopkins University Press, 1994), BMCR 94.09.01. He surprisingly misses B. Isaac, The Limits of Empire: The Roman Army in the East (Oxford: Oxford University Press, 1990), BMCR 1.1.12); D. Potter, “Empty Areas and Roman Frontier Policy,” The American Journal of Philology 113 (1992): 269-74, and (more broadly) S. P. Mattern, Rome and the Enemy. Imperial Strategy in the Principate (Berkeley: University of California Press, 1999), BMCR 2000.06.03.

3. He misses S. P. Mattern, “Counterinsurgency and the Enemies of Rome,” in The Makers of Ancient Strategy: From the Persian Wars to the Fall of Rome, ed. Victor Davis Hanson, 163-184 (Princeton: Princeton University Press, 2010).

4. He overlooks C. J. Fuhrmann, Policing the Roman Empire: Soldiers, Administration, and Public Order (Oxford: Oxford University Press, 2012), BMCR 2012.09.13.

5. The summary of the book on page i correctly has “suppressing insurgencies” while the summary on the dustjacket and on Google Books has “suppressing counterinsurgencies.”