The Fortified Disposition, Part I: Strategic Complexes, Historical Attenuation, and the Return of the Guarded City

This is the first of two companion papers on the return of a fortified disposition to the centre of strategy. The present paper establishes fortification as a movement-slowing strategic complex rather than a simple barrier, traces the long attenuation of that disposition in Western military practice, and examines the first of three contemporary trends: the return of fortified cities through dual-use infrastructure and regulation. The second paper takes up the revival of large-scale static defensive systems and the renaissance of tunnelling and subterranean engineering and draws the overall argument to a close.

The last paragraph of Ian Hogg’s classic The History of Fortification remains as relevant today as when it was written some forty years ago:

It is however undeniable that these recent examples [referring to post-1945 field fortifications] of the art of fortification are usually architecturally and aesthetically less interesting than the imposing products of earlier ages. In recent years, as a result of the activities of preservation societies and groups dedicated to the subject, many more people have discovered the fascinating history of fortification, and many works which would otherwise have been destroyed are being preserved and restored. This is as it should be. The fortress and the fortress engineer have played a vital role in history; it is only meet that their efforts should be respected, preserved and remembered.[1]

Hogg was right to honour that past. He was wrong if the implication is that fortification is finished. Prepared positions still shape operations, often in camouflaged form, and they are likely to weigh more heavily over the next three decades than most strategists now assume. What is returning is a historically normal fortified disposition: fortress design as part of the officer’s expected competence, and protected ground as a first-order strategic asset.

The drivers are only partly technological. Manpower is tight, high-end platforms are expensive, surveillance is persistent, and open movement is increasingly costly. Those are the same structural conditions that once made fortification central. The rest of this paper treats fortification as a movement-slowing strategic complex rather than a simple barrier; traces its long attenuation in Western practice and its present reversal; and then considers the return of fortified cities through dual-use infrastructure and regulation.

Fortified Strategic Complexes

Contemporary strategists should think more about fortifications, but they should also think about them differently. Fortifications are not merely technical solutions to the problem of ballistic protection against particular weapons. They are pieces of monumental architecture, often of immense cost, that reshape landscapes, absorb vast quantities of labour and material, and leave enduring social and cultural marks on the societies that build them. Whether a given fortification ‘works’ against the weapons of its day is only one measure of its significance.

In the popular imagination, fortifications are often conceived as impermeable barriers that either succeed or fail absolutely. In reality, they function more as filters or valves—strategic mechanisms for regulating movement between a controlled interior and an uncontrolled exterior. In military terms they are best understood as movement-slowing machines. By artificially creating friction they compel an adversary’s forces—armies, fleets, logistics trains, or even flows of information and capital—to decelerate, concentrate, expose themselves, and operate at a tempo the defender can absorb and counter. Every successful fortification converts the enemy’s velocity into vulnerability.[2]

The fortified strategic complex—the larger system of mutually supporting works, garrisons, supply nodes and doctrinal practices—is designed precisely to manage that decelerated threat.[3] In slowing the opponent, the complex buys time for reserves, intelligence, political will and the inherent advantages of the defence. A classic illustration is the French fortress system under Vauban, in which individual places were never expected to hold indefinitely but to delay and channel an invader, creating the window for field armies to concentrate or simply exhaust the attacker’s campaigning season.

It must be said that the strategic logic is older than the trace italienne. Crusader and military-order holdings in the Levant functioned as constellations of points that forced an invader to besiege or to leave dangerous garrisons in his rear; Edward I’s castles in Wales hemmed a rebellious principality against mountain and sea; the later Capetian reconstruction of the so-called ‘sons of Carcassonne’ turned a belt of ridge forts into a frontier system covering the approaches to Languedoc. In each case individual places were not expected to hold forever. They were expected to slow, to channel, and to give a thin field force time. Vauban did not invent the fortified strategic complex; he standardised it.[4]

That tradition continued in various forms in France, the Low Countries and elsewhere. Although such systems are often judged to have failed in the Franco-Prussian War, professional soldiers—including the Prussian victors—did not regard fortification as obsolete. Belgian forts suffered spectacularly in 1914, yet elsewhere permanent works proved their value: at Przemyśl, during the prolonged defence of Verdun, and even in the updated Brialmont and Séré de Rivières positions that delayed Patton’s army for three months in 1944.[5] All forts can ultimately be defeated; the relevant question is the cost, in time, men and materiel, of defeating them.

Moltke and the Prussian General Staff were sceptical of the large, self-contained systems associated with Brialmont and Séré de Rivières because they risked absorbing excessive garrisons and constraining the field army. This did not mean they rejected the utility of fortification. On the contrary, they regarded permanent works as valuable when properly subordinated to operational needs—securing flanks, covering concentration areas, or protecting lines of communication—so that the main force retained the ability to manoeuvre and concentrate for decisive action.[6]

It follows that a fortification cannot be evaluated in isolation as a self-contained engineering artifact. Its true value emerges only within a wider operational, logistical and societal architecture that encompasses combined-arms integration, the economic base that sustains prolonged defence, the demographic reservoir that supplies manpower, and the cultural propensity of a people to endure hardship. Strategy, on this view, is never purely military; it is an expression of the total resources and character of a political community.[7]

The Long Attenuation of the Fortified Disposition

In the sixteenth and seventeenth centuries a gentleman—practically by definition an officer—was expected to possess a working knowledge of military engineering. The period produced a wide range of manuals and treatises that a competent military man was assumed to know. That expectation attenuated over subsequent centuries for reasons that were only partly technological. Advances in artillery, and later air power and precision munitions, mattered. Yet there were other, deeper causes. Cities are first and foremost machines for living and centres of economic production; urbanisation eventually pushed them beyond the scale that could be enclosed by continuous defences, while industrialisation and the expansion of commerce rendered walled circuits an economic and spatial burden.[8]

Equally important was the broader strategic shift of the Western world. For much of earlier history, when the West was not the preeminent military power, a relatively guarded disposition had been ordinary. Mobile peoples remained a serious threat well into the early modern period, as John Keegan observed, and settled societies invested enormous effort over millennia in linear barriers to contain them. With the rise of European and later Western imperialism, the principal military efforts of the West were conducted abroad against far less capable opponents. Fortification did not disappear, but its character changed: forts increasingly served as outposts of conquest, fortified trading posts, and armoured administrative centres rather than as the central strategic posture of the metropolitan powers. The open, mobile, expeditionary orientation that characterised much of the nineteenth, twentieth and early twenty-first centuries was therefore the historical exception, not the baseline.[9]

Larry Addington, writing in 1984, portrayed the eighteenth century as a decisive pivot away from a fortified disposition toward systems of war centred on mobility, linear tactics and the open battlefield. Robert O’Connell’s analysis of the cultural and psychological dimensions of weapons and warfare points in the same direction: periods of high lethality and constrained manpower tend to favour defensive depth and the deliberate slowing of enemy movement, while eras of relative resource abundance and lower casualty sensitivity reward mobility.[10]

An economic lens clarifies both the earlier centrality of fortification and its later relative decline. In Castles, Battles, and Bombs, Jurgen Brauer and Hubert van Tuyll show that rulers in the High Middle Ages rationally substituted capital (fortification) for scarce labour. When later resources and relative military superiority permitted large mobile forces and power projection, the opportunity cost of locking capital into fixed works rose sharply.[11]

The literature on strategy is currently seriously lagging reality. Leaving aside narrower contemporary treatments, the last serious English-language study to approach fortification as a living strategic art with a past, present and future was George Sydenham Clarke’s Fortification of 1907. Thereafter the subject largely retreated into specialised engineering or heritage preservation. Fortification never truly disappeared; rather, it expanded in camouflaged and dual-use forms across the global political economy.[12]

That literature has not caught up. The relative prices have changed again: trained manpower and high-end platforms are scarce, open movement is expensive, and prepared ground is once more a rational substitute.

That reversal is already visible in the form still widely assumed to be the opposite of a fortress: the contemporary city. What is returning is not a circuit of medieval walls so much as a guarded, closable urbanism assembled through surveillance, dual-use fabric and regulation. This is the first of the contemporary trends treated in these papers.

The Return of Fortified Cities

To the modern mind, accustomed to the ideal of the open, globalised city, one of the more striking developments is the return of guarded, closable, and increasingly fortified urban forms. In important respects this process is already well advanced. Most major developed cities now operate extensive peripheral electronic monitoring systems—epitomised by the evolution of the City of London’s ‘Ring of Steel’ into a metropolitan-wide surveillance grid—while crowded or high-value sites such as government buildings, transport hubs, stadiums and hospitals have undergone progressive internal hardening.[13]

What is emerging now is a further stage: the physical reinforcement of city peripheries through dual-purpose infrastructure that can function as walls when required, the systematic protection of urban life-support systems (power nodes, communications, bridges and transport arteries), and the development of layered air and missile defences against both high-altitude ballistic threats and low-altitude, low-cost drones.

Three interconnected drivers stand out. The first is the changing character of the military threat. Urban areas are increasingly likely to be central to future operations simply because of the urbanisation of human life. For much of the last century, thinking about city defence treated urban terrain as an incipient fortress. Contemporary doctrine still emphasises the defensive potential of dense and even ruined structures. Ukraine’s Fortress Belt in Donetsk has demonstrated the operational value of prepared urban and peri-urban positions; and similar considerations now shape planning in the Baltic states and Poland.

Lukas Milevski has argued that political imperatives and tactical conditions in the Baltic make static and positional defence more appropriate than classic manoeuvre warfare.[14] The Baltic Defence Line, treated more fully in the companion essay, reflects precisely this recognition: the need to slow, channel and attrit an attacker while protecting key urban centres and buying time for reinforcement.

Israel after 7 October 2023 makes the second driver unmistakable: the return of serious aerial and missile defence as a problem of urban form, not only of batteries in open ground. The border barrier was reinforced, but so were the settlements behind it—walls, protected buildings, strengthened safe rooms, reconfigured approaches. At the same time the existing layered system against rockets and ballistic missiles has been driven downward, toward the low, slow and small threats that now arrive over streets and roofs. Iron Dome, David’s Sling and Arrow still matter. What has changed is the requirement to fold counter-UAS sensors and effectors into the same inhabited fabric those systems were built to protect. The city is no longer merely the object of air defence. It is becoming one of its platforms.[15]

The literature on urban air and drone defence underscores why this is driving physical fortification. Effective defence against low, slow and small drones in cluttered urban environments requires dense sensor coverage, short reaction times and distributed effectors; pure mobile coverage is expensive and incomplete. Layered architectures—detection and tracking, electronic warfare or soft-kill options, and hard-kill interceptors—are widely regarded as essential.

Directed-energy weapons, increasingly discussed as a solution to saturation drone attacks, impose additional demands: they require substantial, reliable power supplies and benefit from pre-prepared, hardened firing positions. The result is pressure to integrate sensors, command nodes, ammunition or power storage, and firing points into the urban fabric in advance rather than relying solely on reactive deployment. Modern flak-tower equivalents—elevated, protected sites for sensors and effectors—are therefore reappearing in planning discussions and sometimes on the skyline, just as hardened shelters and protected critical infrastructure are becoming standard.[16]

In Moscow the process is visible in compressed form. Pantsir systems first appeared on the roofs of the Defence and Interior ministries in 2023 as an improvised answer to long-range drones; they have since been joined by further batteries on civilian high-rises and by purpose-built towers around the capital. What began as an emergency expedient is becoming a standing feature of the urban defence architecture. The same logic, in milder form, is visible wherever counter-drone sensors and effectors are being designed onto rooftops, stadium masts and critical-infrastructure nodes rather than left to mobile teams that arrive after the raid.[17]

The third driver is more controversial but increasingly difficult to ignore. Where the risk of serious internal conflict or contested control of territory rises, cities develop a more guarded relationship with their hinterlands. Infrastructure becomes a target; boundaries harden; and siege-like dynamics reappear in new forms.[18]

A crucial and often underestimated mechanism propelling these changes is regulation. The extensive alteration of cities for counterterrorism has been an enormous collective effort, yet it frequently escapes notice precisely because the instruments that drive it are so banal. Instead of dramatic political declarations or large, visible defence budgets, the process advances through incremental changes to design codes for the protection of crowded places, revisions to actuarial tables, adjustments in insurance contracts, and planning requirements imposed on developers.

These measures shift the burden of expense onto private actors and local authorities while steadily embedding protective features into the built environment. In the United Kingdom, for example, the National Barrier Asset—a substantial stockpile of concrete and other barriers controlled by the Home Office and deployed across the country—remains almost invisible even to the eyes of many security and strategy specialists, largely because its components are so prosaic. The cumulative effect, however, is a significant hardening of urban space achieved through administrative and regulatory channels rather than overt military programmes.[19]

The same regulatory logic can be extended to more explicitly military considerations. Imagine a development project in a city whose building-approval guidelines now incorporate defence-planning criteria. A developer submits plans for four buildings of equal height, spaced evenly and oriented to maximise sunlight on the most expensive units. Approval is granted only on condition that three buildings are lowered and one raised to give its upper floors clear observation along an anticipated avenue of approach; that selected floors are structurally strengthened to support heavy weapons; that the complex is reoriented so an artillery piece sited in the central courtyard is shielded on all sides by the surrounding structures; and that part of the underground parking garage is heightened to allow a self-propelled gun to enter and exit.

Does this not sound remarkably like a classic gun bastion, with casemates for the protection of shot and shell and an elevated cavalier serving as a central command and fire-control position? That is precisely what it is—while remaining a perfectly functional apartment complex. The additional costs are borne by the developer and passed on to purchasers; they do not appear as a direct charge on the military budget. The defensive function of the complex remains entirely latent until activated. Multiplied across numerous projects, such requirements would gradually reshape the urban fabric into a latent fortified strategic complex without the political visibility or fiscal profile of a conventional fortification programme.

If all of this sounds strange or improbable, one must recognise that cities are constantly mutating. Contrary to ordinary human perception, cities on a macro scale are highly fluid. Some morphological changes respond to defence considerations; many others respond to economics, technology or simple fashion. The concept of dual-purpose defensive architecture is not new. In numerous historic walled towns, the outer circuit was formed simply by requiring that buildings on the perimeter connect to one another and present blank or minimally fenestrated walls at lower levels. At times defensive needs predominate, and walls are raised or boulevards are turned back into bulwarks; at other times the reverse occurs, and bulwarks are converted into boulevards.

Vienna provides the classic historical precedent for this transformation. The city retained its walls and broad glacis longer than most major European capitals. In December 1857 Emperor Franz Joseph I ordered their demolition and the creation of a grand circular boulevard on the freed land. The resulting Ringstraße converted a military perimeter into a prestigious civilian artery lined with monumental public buildings, parks and residences. The old gates disappeared as fortifications, yet their locations remain legible in street names and the alignment of the boulevard itself. The later wartime flak towers—massive concrete structures that proved too costly to demolish—further illustrate how heavily reinforced works, once built, tend to persist within the urban fabric. Arterial structures created by the removal of walls can, under new strategic conditions, be adapted back toward defensive roles.

More prosaic examples exist closer to home. In 1940 a village in Kent incorporated into its anti-invasion defences a ditch-and-berm barrier originally constructed a thousand years earlier by Alfred the Great against the Danes; a modern pillbox was simply dug into the still-functioning ancient earthwork. The defences of Dover Castle, and of Dover more generally, exhibit the same layering: Roman walls, medieval and later fortifications, twentieth-century anti-aircraft positions and dragon’s-teeth anti-armour obstacles, together with an extensive underground command-and-control complex.[20] New and old elements continue to coexist and, when required, to reinforce one another.

The open, sprawling city of the late twentieth century was the anomaly. The Chinese character for city, 城, is a walled enclosure; that older morphology is returning, more often through regulation and dual-use fabric than through declared walls.

Conclusion

That character is not an ornament but a reminder. For most of urban history a city was a place that could be closed, watched and held. The unfortified, globally open metropolis of the late twentieth century was the exception, made possible by Western military preponderance, cheap movement and the assumption that serious war would happen somewhere else. Those conditions are eroding. Manpower is scarce, high-end platforms are expensive, surveillance is persistent, and open movement is costly. Under those conditions the city again becomes a machine that can be hardened.

None of this should surprise anyone who has looked carefully at Seoul since the end of the Korean War, during which time it has prepared dual-use buildings against the possibility of renewed conflict. River-front blocks from the 1970s contain stairwell gun ports and reinforced firing floors; at least one mixed-use complex on an approach to the old presidential compound was built heavy enough to serve as a barricade. Contemporary reporting has also described estates designed for rapid demolition to throw rubble across axes of advance, though the documentary trail is firmer for the first two practices than for the third.[21]

What looked like a Korean peculiarity is becoming ordinary far from the peninsula, and not for dissimilar reasons. Persistent aerial threat, thin field forces, and the political necessity of protecting dense civilian centres are no longer a Northeast Asian special case.

Ian Hogg closed his history by honouring the fortress and the fortress engineer as figures who had played a vital role and deserved to be remembered. He was right about the past. The implication that their role had ended does not survive contact with the present city. Fortress design is returning to the officer’s expected competence, even when it arrives disguised as a planning code, an insurance requirement or a latent structure in an apartment block. The engineer who can read ground, integrate sensors and effectors into fabric, and treat the city as a fortified strategic complex is no longer a heritage specialist. That is the first contemporary face of the disposition whose older history this paper has traced.

The companion essay turns to the other two: the revival of large-scale static systems and the renaissance of tunnelling.