”Men live upon the land and not upon the sea. Great issues between nations at war have always been decided… by what the army can do against the enemy’s territory and national life.” – Julian Corbett
The distinction between front lines and rear areas has long shaped military thinking. Armies fought at the front while the economic and industrial foundations of national power operated beyond the immediate reach of combat. Distance provided protection. Geography created strategic depth. A state’s ability to sustain war depended not only on military strength but also on the security of the economic, industrial, and logistical systems that supported it. Resent development in warfare is now changing the understanding of strategic depth. The emerging use of relatively cheap long-range drones for precision strikes against critical infrastructure erodes the protective value of distance. Different key targets like energy facilities, logistics hubs, manufacturing plants, transportation networks, and ports are increasingly vulnerable. States are entering an era in which there may be no safe rear area.
Drones are maybe more often seen as tactical innovation, but they maybe have an even greater strategic significance. Looking at drones, they seem to enable a form of warfare which was formulated more than a century ago by the British maritime strategist Julian Corbett. Although Corbett wrote about strategy during a time of imperial competition and the new technology for the time was battleships, his insights about national power and indirect strategy could form a strong framework for drone warfare today. Corbett is often associated with naval warfare, but his most important work was on theory of strategy. While his contemporary thinkers were emphasizing decisive battles, Corbett viewed military force primarily as a means of shaping the conditions under which an opponent could continue to resist. Control of communications, trade, and access to resources allowed states to apply pressure not only against military forces but also against the economic and political foundations of power. In contemporary terms, this logic is visible in forms of economic warfare that seek to disrupt an adversary’s national resilience and ability to sustain military operations. The aim for naval forces was to control trade, communications, and the movement of resources, as that is the foundations of an adversary’s power. Supressing the foundation of power means winning without fighting battles. One contemporary interpretation of Corbett’s insights is that they highlight the strategic importance of economic warfare and attacks on systems that sustain national resistance. This is more of an indirect strategy than in line with the Corbett’s contemporaries strive for the decisive battle.
Corbett formulated a more systemic understanding of warfare than his contemporary thinkers and used the concept of “national life”, which was a contemporary common political and strategic expression to describe the broader political, economic and social foundations upon which military power depended as well as the general standard of living. This leads to the idea that wars can be won by pressuring or disrupting the different systems in a nation’s national life. Among these foundations, energy occupies a uniquely important position. Because energy underpins production, transport, communications, and military operations, disruptions can create cascading effects throughout both the economy and the defence. Energy infrastructure therefore functions as a strategic node whose degradation can weaken multiple sectors simultaneously.
Historically, pursuing strategies aimed at disrupting an adversary’s national life required substantial resources. States needed powerful fleets, strategic bombers, overseas bases, or long-range missile capabilities to reach deep into an opponent’s economic infrastructure. Strategic reach was consequently reserved for major powers. Long-range drones are altering that relationship. By providing surveillance and precision-strike capabilities at a fraction of the cost of traditional platforms, drones significantly reduce the financial and technological barriers to strategic reach. The ability to conduct indirect warfare against an adversity’s national life, is becoming available to a much wider range of actors.
Recent conflicts provide numerous examples of the kind of indirect pressure upon national life that Corbett considered central to strategy. In many cases, drones and other relatively low-cost strike systems are being used not primarily to destroy military formations but to influence the economic, logistical, and political foundations that sustain military power. Ukraine’s long-range drone attacks against Russian oil infrastructure is a clear contemporary example. By attacking refineries deep inside Russian territory, Ukraine have found a way to hit Russia’s production and distribution of oil-based resources thus slowing down both Russian economy and military operations. Ukraine has also conducted several strikes against facilities associated with Russia’s defence-industrial sector, including enterprises linked to the production of microelectronics, microchips and other components essential for drones, missiles, and precision-guided weapons. They therefore illustrate Corbett’s central insight that strategic advantage can be gained by applying pressure to the economic, industrial, and technological foundations of war rather than to battlefield forces alone.
The Houthi campaign against commercial shipping in the Red Sea provides another example that closely resembles Corbett’s original maritime framework. Rather than seeking decisive naval battle, the Houthis have attempted to influence international trade by threatening one of the world’s most important maritime communication routes. The resulting increases in insurance costs, rerouting of shipping, and disruption to global supply chains demonstrate how relatively weak actors can exert strategic influence by targeting the flows upon which economic activity depends. During the entire war, Russia have repeatedly attacked Ukrainian infrastructure, but not with the same narrow focus as Ukraine have used, which further illustrate how attacks are made against the opponent’s national life. For all contemporary examples of this type of indirect strategies, the intended effect extends beyond immediate military outcomes and aims instead at weakening the systems that enable national resistance over time.
Taken together, these cases reflect a distinctly Corbettian logic but with much cheaper equipment than battleships. This growing availability of relatively inexpensive technologies will allow both states and non-state actors the ability to disrupt in unprecedented reach and scale. The strategic significance of drones lies less in their effectiveness than in their ability to make indirect warfare vastly more affordable.
Modern economies have achieved remarkable efficiency through economies of scale, specialization, concentration, and interconnected global supply chains. Interesting is that Corbett opposed the concentration of naval forces in his days, while many thinkers was for it. In peacetime, concentration makes economic sense, but in conflicts this results in a concentration of key target instead. Striking at the right critical function can produce cascading effects that disrupt far larger economic and military systems. These functions used to benefit from being at a distance from the frontline, but as this is changing a new form of understanding of depth in strategic terms is needed. By adding the modern understanding of depth to Corbett’s usage of the term national life, we should perhaps think in terms of Adaptive depth and let adaptive depth be a state’s ability to absorb disruption, restore functionality, and regenerate capability. It depends upon distributed production, infrastructure redundancy, diversified supply chains, reserve capacity, innovation, effective civil-military coordination, and institutions capable of acting and learning under pressure. A state possessing adaptive depth can continue functioning despite repeated attacks against critical systems, limiting disruption and preventing strategic paralysis. Innovation is particularly important because it enables societies to adapt to new threats and reduce the long-term effectiveness of disruption campaigns. Adaptive depth therefore extends beyond resilience understood merely as recovery. Adaptive depth seeks recovery, regeneration and adaptation while the attack is still ongoing.
These developments are also transforming deterrence. Traditionally, deterrence rested largely on punishment. Adversaries were discouraged from aggression because they feared retaliation and unacceptable costs. Drone warfare complicates this logic. As the cost of long-range precision strike decreases, defending every critical asset becomes increasingly difficult and expensive. Complete protection becomes unrealistic. Under such conditions, deterrence increasingly shifts toward denial. Rather than persuading an adversary that retaliation will be painful, denial seeks to convince them that attacks will fail to achieve meaningful effects. Resilience therefore becomes a core component of deterrence itself. More than a century ago, Corbett argued that wars are often decided through their effects on national life rather than through the destruction of military forces alone. The rise of long-range drones suggests that his ideas are becoming more relevant rather than less. Warfare is increasingly shifting toward resilience and adaptability of national systems.
For Sweden, the implications of this shift extend far beyond military modernization. From a Corbettian perspective, Sweden’s ability to deter aggression will depend not only on its capacity to retaliate but also on its ability to ensure that attacks fail to achieve meaningful strategic effects. Deterrence by denial therefore becomes closely linked to adaptive depth. Strengthening Sweden’s adaptive depth requires reducing the vulnerabilities created by concentration and dependency. Sweden’s highly efficient economic and logistical systems have generated significant prosperity, but efficiency can also create strategic fragility. Both the road network, particularly the main TEN-T corridors, and the railway system are concentrated around a small number of critical routes and nodes. Increasing redundancy and maintaining spare capacity within transport networks, ports, and logistics infrastructure would improve the ability to reroute flows and sustain societal functions during periods of disruption. Capacity that may appear economically inefficient in peacetime can provide valuable strategic depth during crises and conflict. However, one should not automatically assume that increasing adaptive depth is expensive, it may also be economically profitable.
Energy security occupies a particularly important position within this framework. A more distributed energy system based upon diversified electricity generation can reduce vulnerability to attacks against critical nodes. Increased use of rooftop solar installations, together with batteries and heat pumps would allow a larger share of essential societal functions to operate independently of disruptions affecting the broader grid. Small-scale hydropower, many of which have been shut down in recent decades, contribute both to economic growth and resilience. Large-scale power generation and transmission networks will remain indispensable, but their relatively limited number makes them easier to defend and protect. Resilience is therefore strengthened when centralized and decentralized solutions complement one another. As the new technologies allow striking more targets at lower cost, any situation where a decentralized solution or infrastructure is competitive to a centralized, it is better to choose the decentralized.
Industrial capacity and technological competence constitute a second pillar of adaptive depth. Sweden’s ability to diversify sources of critical components and maintain domestic production becomes increasingly important. Equally important is the preservation of technological expertise and innovation ecosystems capable of adapting rapidly to changing military and economic conditions. Adaptive depth depends not only upon what a society can produce today, but also upon how quickly it can develop and regenerate capabilities tomorrow.
Finally, adaptive depth depends upon society’s ability to mobilize and coordinate under pressure. Within the framework of Total Defence, a more decentralized crisis-management structure could strengthen resilience by placing greater responsibility upon regions, municipalities while maintaining national coordination through central authorities. Such an approach reduces reliance on a limited number of decision-making centres and enables faster adaptation. From a Corbettian perspective, the ultimate purpose of these measures is not simply to withstand attack but to deny an adversary the strategic effects it seeks. In an era where no rear area can be assumed safe, adaptive depth may become one of the most important foundations of national deterrence. In Corbettian terms, the objective is not merely to defend infrastructure but to preserve the functioning of national life under conditions of sustained pressure. As the threats are being decentralized now that attacks can happen everywhere, the management of the effects need to be equally decentralized. This means that societies’ ability to heal themself from damage may rely increasingly on municipalities, NGOs, local companies, the local sports clubs, or whatever actors that can bring together a local workforce and others means for fixing problems. It may be more important to arrange training of these actors than increasing the capabilities of the national authorities.
In an era where no rear area can be assumed safe, the central strategic question is changing. The issue is no longer how to prevent every attack, which is increasingly impossible. The issue is whether society can continue to function when attacks succeed. Corbett understood that wars are ultimately contests over national life. Drones have not altered that reality, what they have altered is access to disruption. By dramatically lowering the cost of strategic reach, they have made indirect warfare available to states and non-state actors alike. This demands a renewed understanding of national life itself. A nation must possess not only resources, infrastructure, and military power, but also the capacity to absorb shocks, regenerate capabilities, and adapt faster than its opponents. This article calls that capacity adaptive depth. The decisive advantage will belong not to the actor that inflicts the greatest damage, but to the one that remains functional while damage is being inflicted. In the emerging age of persistent disruption, victory will depend less on destruction than adaptation.
Daniel Ekwall is Professor, University of Borås and Swedish Defence University.
Per Ödling is Professor, Lund University.