The Changing Character of Combined Arms


Debates are raging the about tanks and how well individual services, like the U.S. Marine Corps, are responding to the requirements of great power competition. Retired generals question the utility of lighter expeditionary forces reliant on missiles while younger officers and thinkers are more open to experimentation and debate based on insights from conflicts like Ukraine and contingencies beyond the Indo-Pacific. In the U.S. Army, the multi-domain task force ushers in a new era which will be increasingly dominated by long-range precision fires combined with electronic attack and cyber operations. Disagreements center on whether the U.S. Army should focus on converging effects at the tactical level (close combat) or at the operational level, penetrating and disintegrating layered enemy anti-access/area-denial systems. The U.S. Air Force envisions a future where the air component develops the doctrine, training, and technology necessary to accomplish operational maneuver — untethered from large, static basing.

These debates produce an unappreciated competitive advantage: a healthy marketplace of ideas in the profession of arms. What the dialogue to date lacks is a broader conceptualization of how the character of combined arms is changing in what is best described as the new missile age. The ability of tactical units — from squads to individual fighter aircraft — to conduct precision strikes across the depth of the battlefield, all captured and circulated on social media, changes how we think about tempo, decision-making, and combined arms. Below we describe some of the larger trends changing combined arms and what it means for military innovation and adaption going forward. We seek to develop a framework for further debate and defense planning biased toward experimentation and testing that moves away from idol worship built around legacy platforms and ideas.



The Nature of Combined Arms

Just like war, there is an enduring nature and changing character to combined arms. Combined arms involve combining capabilities in a simultaneous manner to prevail. Traditionally, this combination involved indirect and direct fire to support ground maneuver and closing with the enemy. For Stephen Biddle, the essence of combined arms is captured in the concept of force employment. Warfighting is less about mass and more about maneuver, using tempo and targeting to put the enemy on the horns of a dilemma that reduces cohesion. Seen another way, combined arms is about the combination of effects: fire and maneuver, direct and indirect approaches across domains, orthodox and unorthodox ways and means. Combined arms reduce the decision space of the adversary. The more effects a force brings to bear in time and space, the more likely the enemy system is to collapse.

The concept is tactical but finds resonance in 19th and 20th century operational maneuver. The Prussian military elite dreamed of universal principles and schemes of maneuver based on the 216 BCE Battle of Cannae. The concept of fire cauldrons, or kesselschalt, was a key component of offensive planning. As artillery grew more powerful and shifted from direct to indirect fire assets and aircraft entered the fight, these concepts transitioned to modern mechanized warfare and blazed a trail of destruction. Arguably this art of battle (i.e., tactics) struggled to bridge operational art and campaigning to achieve true strategic objectives. Yet it has enduring value and serves as a template for combat to this day.

Offsets and Decisions: The Emerging Character of Combined Arms

Military organizations are complex entities that reflect a mix of political, social, and technological factors limiting how a group — be it a state or armed movement — mobilizes people and resources to produce combat formations. Political institutions alter military doctrine. Cultural and social structures shape tactics. Advances in technology change this process and modify how nations generate and apply combat power. In modern military thinking, offsets provide an example.

Offset strategies propose using technological superiority (qualitative advantage) to overcome conventional military mass (i.e., quantitative advantage): The better beats the many. The first offset, or what Bernard Brody called “the missile age,” saw thinking about both the balance of power and strategy change as a result of nuclear weapons and advances in long-range strike. The advent of thermonuclear weapons set off a cascading series of debates about risk, escalation, and second-strike capabilities. The U.S. Army experimented with new approaches to combined arms on a nuclear battlefield as well as increasing conventional forces to provide more flexible response options. New technology, filtered through images of future war linked to military tradition and pop-culture imagination, changed the character of combined arms.

An offset strategy assumes governments can mobilize resources and drive the innovation process relative to a great-power competition, combining a mix of national labs and federal funding with private-sector initiatives and rapid experimentation to produce new combat formations. This line of thinking defined the second offset, in which groups like the Office of Net Assessment and the Defense Advanced Research Project Agency built the concepts and capabilities to realize what Soviet theorists called a military-technical revolution. Taking advantage of the information revolution and advances in digital technology, precision conventional strike could produce effects equivalent to counter-force nuclear weapons, creating what are today called strategic non-nuclear weapons. The third offset added advances in robotics (i.e., autonomous systems) and AI/machine learning to enhance precision strikes, creating a new competitive strategy on display in concepts ranging from expeditionary advanced base operations that seek to hold the Chinese navy at bay to multi-domain tasks forces and mosaic kill-webs.

Over the last generation, this offset logic has led to the proliferation of precision-strike capabilities at the tactical, operational, and strategic levels — blurring the levels of war and increasing the lethality of conventional forces. It stands to reason that as technological trends lower the cost of precision-strike networks — to include in tactical formations — the character of combined arms starts to change.

It is not just lethality that is changing war, but the ripple effects of network society. As globalization and digital technologies create new social and political forms, information and cyber operations become central political contests, including those involving arms and violence. It is not enough to destroy a Russian tank. You have to upload a video as well to mobilize public opinion and galvanize will. The proliferation of precision strike in a connected world alters battlefield geometry and creates a new character to combined arms: What can be seen can be hit, and what can be hit can be destroyed. What can be uploaded can mobilize people and resources.

When it becomes easy to kill what you can see, the challenge of combined arms rests in decision architecture and using scalable, Uber-like mechanisms to synchronize fires and effects across the compressed levels of war. In contrast to mass, firepower, or linear maneuver-based warfare of the past, the defining characteristic of modern war is decision. The blurring of political, informational, and military spheres not only increases the complexity of the operating environment, but also produces a a level of data that tends to overwhelm  decision makers. This challenge is compounded by the shrinking of operational battlespace with non-nuclear missiles that can traverse thousands of miles, multiple combatant commands, and a dizzying array of competing command authorities. While tactical engagement, massing fires, and effective sustainment remain the foundation of effective warfighting, an ability to cut through the complexity and make effective decisions faster than an adversary is the new high ground. Tempo is becoming more about the relative speed of judgment than action. Much of this advantage is gained through effectively processing what can amount to petabytes of data — a task impossible for a single human and difficult for large staffs. The dominant force in future conflict will likely apply AI/ML to aggregate data, parse trends, identify patterns, and pass the results to humans to apply context and make decisions, all while monitoring how battlefield effects change social media themes and messages.

In the U.S. military, the engineering and capabilities required to adapt to the changing character of combined arms exist (just look at Project Convergence), but the mental models, doctrine, and tactics lag behind. U.S. military dominance on display during the 1991 Gulf War ushered in a decade of military cognitive stagnation. The U.S. Air Force figured, why fix what didn’t seem broken? The Army and the Marine Corps laid out bold visions but struggled to adapt due to contingency operations and diminished budgets. Despite noble efforts to transform the entire defense enterprise after 2000, the next decade focused on counter-terrorism and counter-insurgency, distracting military thinkers from considering the changing character of combined arms. Efforts to imagine future war found it difficult to escape the gravity of old service programs and key platforms.

While the U.S. military fought across both the Middle East and the bureaucratic battles in the beltway, Russia and China gathered their notes from 1991 and designed a future fire-centric force that could hold U.S. power projection at risk. By the mid-2010s, U.S. military thinkers began to wake up to the reality of a new missile age but responded to the threat with paradigms of the past. To the prospect of more missiles, they called for more maneuver-championing legacy platforms like tactical aircraft and tanks.

The threat of complex, constant missile attack is only one part of the new operational environment. The blurring of traditional battlefield lines through the reemergence of gray-zone competition and global connectivity reinforces the shift in the dominant characteristic of war from maneuver to decision. A more tactically maneuverable army or air component certainly gains some advantage, but that same force in a modern salvo exchange, facing hundreds of low-cost munitions, will likely fare as well as dexterous Prince Oberyn against massive Gregor Clegane. Gray zones and salvo exchanges are the new coins of the realm, not mass tank or air-to-air battles.

Combined arms in the new missile age should seek machine-enabled decision advantage — sensing, deciding, and acting within an adversary’s decision cycle. The sheer complexity will require algorithmic judgment, using AI and especially machine learning to help prioritize which aircraft and missiles to engage given logistical considerations like ammunition stockpiles, the probability of future battles, and shifting political limitations associated with escalation risk. While the nature of combining effects will not change, the character will increasingly stress synchronization and optimization over mass and maneuver. Combined arms will become less about memorized battle drills and human intuition and more a function of augmented consciousness. Machines will offload cognitive tasks from humans to free up space for improvisation and creativity within the bounds of the mission. It will increasingly involve mosaic kill-webs that can be tailored and scaled — and this will produce an urgent need to rethink how we educate and train military professionals for future war.

The Road Ahead: Hypothesis-Testing through Experimentation

In moments of transition like this, the best course of action is to engage in what Carl von Clausewitz called critical analysis. Clausewitz differentiated chronological history — common still in many operational and official histories used in professional military education — from causal explanations of events that facilitate evaluating ends, ways, and means. Criticism starts by identifying equivocal facts — embracing rather than wishing away uncertainty and competing perspectives — and tracing “effects back to their cause” to form testable hypotheses. For Clausewitz, the process helped professional officers hone judgment through analyzing historical military campaigns as counterfactuals. In modern strategic analysis, this process translates into embracing social science methods and continuous experimentation to identify and evaluate new ways and means for combining effects.

While change is constant, the future is unknown. The military professional can see the outline of the future but struggles to find the optimal investments to combine effects at the tactical, operational, and strategic levels. Too often, the methods used to determine a way ahead — from wargaming to defense scenarios — tend to lack robust samples and risk overgeneralizing from narrow cases that may not reflect how war is changing. Just as international relations for years abused 1914 as a crucial case to hypothesize the causes of war, the national security community runs countless wargames that often wish away politics and logistics and, worst of all, lack enough iterations to draw even bounded conclusions. They propose to generate ideas, not evaluate hypotheses.

The services struggle to conduct force-design experiments in a manner that allows them to compare findings from across wargames and field exercises in a meaningful analytical manner. Take the U.S. Marine Corps:  While the service used an iterated series of wargames on the road to Force Design 2030, the use of non-disclosure agreements limited the ability of a larger community to debate the merits of the findings or run competing experiments that falsified the design. The net result? What Karl Popper called pseudo-science and an increasingly emotional as opposed to rational debate. The marines are not alone. The national security community is littered with unfalsifiable anecdotes that cost the taxpayer billions of dollars.

The way out of this trap is to inject new life into old traditions: wargaming and experimentation. Wargaming is as old as the military profession and can be adapted to generate and test new ideas rather than exclusively generate understanding. Building an infrastructure to capture data from wargames at the echelon of command and run randomized control trials could accelerate adapting to the changing character of combined arms. Beyond testing ideas, the captured data could also be used to refine AI applications likely required to synchronize effects on multidomain battlefields in the future.

The military learns by playing war. Experimental units and campaigns of learning are old traditions in the military profession that could be revolutionized by incorporating data science and the scientific method. In both the lead-up to World War II and the aftermath of the Cold War, the U.S. Army used the Louisiana Maneuvers to explore new tactical and operational force designs. Combining experimentation and wargaming, the Army used the Howze Board to accelerate air mobility and air cavalry in the 1960s and the high-technology testbed in the 1980s to explore lighter, more mobile infantry formations. The Marines employed experiments and experimental units in both Sea Dragon efforts in the 1990s, a tradition that continues today.

While efforts like Project Convergence and Force Design 2030 replicate the best of these traditions, they can transcend the trap of pseudo-science by showing their homework and subjecting themselves to rigorous hypothesis testing. The foundation is there. The data just needs to be captured, structured, and independently tested to validate the predictions. The process will need to be transparent so that it can be replicated — the gold standard in modern science.



Benjamin Jensen, Ph.D. is a professor of strategic studies at the School of Advanced Warfighting, Marine Corps University, and a senior fellow for future war, gaming, and strategy at the Center for Strategic and International Studies. He is also a reserve officer in the U.S. Army.

Col. Matthew Strohmeyer is a U.S. Air Force officer and a military fellow at the Center for Strategic and International Studies.

The views expressed are their own and do not reflect the views or policies of Marine Corps University, the U.S. Marine Corps, the U.S. Air Force, the Department of Defense, or any part of the U.S. government.

Image: U.S. Army photo by Spc. Michael Baumberger