Journal of Advanced Military Studies

https://doi.org/10.21140/mcuj.20261701005

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Abstract: Despite general agreement from theorists and historians on its importance, the military will to fight does not have an accepted doctrinal definition. This, combined with doctrine, theory, and practice that focuses exclusively on destruction of enemy will to fight without mention of preserving U.S. will to fight, cultivates an environment where the presence of American will to fight becomes an unacknowledged planning assumption. Remedying this through doctrinal revisions (and corresponding discussion and assessment) facilitates an operational planner’s ability to incorporate efforts into planning specifically to preserve the U.S. will to fight, using objective, risk, tempo, narrative, and the interplay between national and military will to fight.

Keywords: will to fight, planning assumption, doctrinal definition, combat motivation

The apparent belief that the will to fight is inherent in society at large is a deadly dangerous assumption, one that could lead us to a tragedy of terrible proportions. . . . Our Army’s inability to measure its own moral-psychological readiness appears to be matched by an inability to take the measures necessary to improve its situation.

~ William L. Hauser^[1]

Introduction

The concept of the American will to fight and the imagery that dramatizes it predates the founding of the nation and continues to occupy a prominent place in contemporary media and military culture. Emmanuel Leutze’s iconic painting Washington Crosses the Delaware depicts General George Washington standing resolute at the bow of a small boat as 13 men prepare to strike the Hessian garrison at Trenton during the Revolutionary War. The national anthem memorializes the defense of Fort McHenry during the War of 1812. Joe Rosenthal’s photograph of U.S. Marines raising the American flag on Iwo Jima is emblematic of sacrifice and grit during World War II and the battles in the Pacific. Images from the Chosin Reservoir capture endurance under extreme conditions during the Korean War. More recent depictions of small-unit actions during the Global War on Terrorism in major motion pictures reinforce a narrative of enduring American military resolve. Collectively, these images suggest a persistent and inexhaustible American will to fight. However, despite the extent to will to fight is mythologized, military planners (and the public) should not conflate the persistence of these images with permanence of the U.S. military will to fight. Unfortunately, limited clarity and minimal explicit discussion on the U.S. military will to fight cultivates an institutional environment where the permanence of the will to fight becomes an unacknowledged planned assumption. To mitigate this, U.S. military doctrine should jointly define the will to fight, incorporate the requirement to protect it into planning, and examine methods for doing so.

While military planners may already make implicit efforts to acknowledge and assess assumptions regarding the U.S. military will to fight, the current disconnect between doctrine, theory, and practice makes this challenging. Military doctrine focuses exclusively on the destruction of enemy will to fight. Rooted in Carl von Clausewitz’s theory of war as a contest of wills, military thought frames the destruction of adversary will to fight as a necessary precursor to victory but fails to recognize a corresponding requirement to protect friendly will.^[2] Joint Campaigns and Operations, Joint Publication (JP) 3-0, describes the destruction of enemy capability and the will to fight as a prerequisite for achieving strategic objectives.^[3] The Army’s Operations, Field Manual (FM) 3-0, goes further, asserting that “leaders do everything possible in the physical and information dimensions to reduce the enemy’s will to fight.”^[4] Yet, neither document addresses the protection, or even assessment, of the U.S. will to fight. Instead, Joint doctrine’s discussion of the protection function focuses primarily on tangible equipment and infrastructure without addressing the human element of the will to fight.^[5]

Military theory perpetuates this imbalance and the fallible assumption that U.S. military will to fight is permanent and can be relied on when needed. Like doctrine, military theory overwhelmingly emphasizes how to destroy an adversary’s will or the importance doing so without offering a corresponding opinion on how to protect or cultivate will to fight within an organization. In practice, many wargames highlight unacknowledged assumptions about the will to fight when simulated formations respond to all orders without hesitation or deviation.^[6] History further reinforces propagation of this assumption, with an all-volunteer American force performing admirably in recent conflicts. Combined, these institutionalized elements predispose the presence of U.S. military will to fight to persist as an unacknowledged planning assumption that is rarely defined, seldom assessed, and hinders protection efforts in military planning.

Joint Planning acknowledges that assumptions are unavoidable, but it also warns that “using assumptions incurs risk.”^[7] While planners may implicitly recognize the potential for degradation in military will to fight, this should be explicit and incorporated in planning. Treating the U.S. will to fight as an assumed constant invites risk to both mission and force, especially as future conflicts may transition to near-peer engagements with potentially higher casualty rates and more direct threats to forces. Overall, misjudging combat motivation may lead to war expansion, faulty predictions about duration or intensity, and miscalculations about feasibility. When the will to fight declines unexpectedly, military effectiveness suffers and civil-military tensions often follow and reciprocally reduce military will to fight. Failure to acknowledge the military will to fight as an assumption reduces planners’ ability to understand or accommodate its fluctuations. During planning and execution, collection occurs to validate assumptions, but the current institutional treatment of the will to fight prevents this from occurring.^[8]

When the institution recognizes the U.S. will to fight as an assumption rather than a fact, planning considerations around it necessarily change. The will to fight should be treated as a friendly capability, one that commanders and planners should never assume will always be available.^[9] This reframing is neither pessimistic nor a political statement. Rather, it provides planners with a framework for understanding the will to fight and designing operations that protect it. Achievable and legitimate objectives, acceptance of prudent risk, deliberate manipulation of tempo, and coherent narrative construction offer planners leverage points to sustain and strengthen American combat motivation. Such an approach, however, requires confronting the unacknowledged assumption that the U.S. will to fight will always be present when needed.

An Undefined but Important Assumption

While Clausewitz is perhaps the most frequently cited (and misquoted) theorist on human will in war, he is not alone in recognizing the significance of combat motivation. There is broad consensus among military theorists and professionals that the will to fight is a critical, if not decisive, factor in warfare. When Army general Scott D. Berrier, director of the Defense Intelligence Agency, was asked about combat motivation in the context of the 2022 Russo-Ukrainian War, he observed, “I think it has been everything.”^[10] Despite this acknowledged importance, United States defense institutions have repeatedly struggled to assess, predict, or influence the will to fight. A 2018 Rand study, Will to Fight: Analyzing, Modeling, and Simulating the Will to Fight of Military Units, concluded that U.S. military and political leaders have “misjudged, discounted, or purposefully ignored the will to fight, even as they were presented with convincing evidence that will to fight might be their undoing.”^[11] During a 2022 Senate Armed Services Committee hearing, Senator Angus King (D-ME) noted that within a single year, the United States underestimated Ukrainian combat motivation while overestimating the will of the U.S.-trained Afghan National Army.^[12] Similar miscalculations occurred in Korea and Vietnam. In each case, incorrect assumptions about the military will to fight distorted both strategic and operational planning.

Meaningful discussion of any multifaceted concept requires definitional clarity. Yet, U.S. doctrine has never defined “will to fight.” Although Clausewitzian language referencing will appears throughout Joint and service doctrine, no consistent definition or component framework exists.^[13] Rand defines the military will to fight as the “disposition and decision to fight, to act, or to persevere when needed.”^[14] By framing will as an decision, Rand implicitly acknowledges its impermanence, uncertainty, and overall status as an assumption. To capture its operational relevance, this article defines the military will to fight as the cognitive capability to engage in and sustain combat operations as required to achieve the unit’s mission. Absent a shared definition, planners cannot accurately identify the will to fight as a potential assumption, assess its durability, or design operations to preserve it.

Doctrine

If military will to fight is treated as an assumption rather than a capability, that assumption should be visible in doctrine. This does not occur. Since doctrine reflects institutional values, priorities, and organizing principles, examining how U.S. doctrine does address the will to fight reveals not only what the military emphasizes, but also what it systematically neglects. Tracing the doctrinal evolution of the will to fight therefore clarifies how the U.S. military has been understood, constrained, and operationalized (or not) the concept of military will to fight within planning. During the past century, doctrinal treatment of the will to fight has oscillated between two broad approaches.

The first is an internally focused perspective, primarily at the tactical level, emphasizing leadership, cohesion, and the development of effective fighting teams. This approach dominated interwar doctrine and reflected a renewed emphasis on the “human factor” following the psychological toll of World War I.^[15] The second approach, which emerged more prominently after World War II and remains prevalent today, is externally focused and emphasizes targeting and degrading an adversary’s will to fight. Driven in part by technological advances, particularly the rise of airpower, this latter perspective increasingly framed the will to fight as something to be destroyed in the enemy rather than protected within one’s own force.^[16]

The introspective, protective perspective appeared first. During the 1920s and 1930s, reflection on the psychological demands of industrialized warfare prompted military leaders to reengage with the “human factor” described by Clausewitz.^[17] The 1939 edition of Operations, FM 100-5, defined combat power as consisting of morale and fighting ability and introduced “will to fight” as an element of a unit’s “combat value.” The manual acknowledged both intrinsic and external influences on combat motivation, as well as the relationship between military and national will.^[18] It asserted that a soldier “readily accepts symbolic ideals implanted by tradition and national culture and will fight for these ideals when he is aroused,” reflecting an early appreciation of motivation as socially constructed, situational, and contingent.^[19]

Following World War II, doctrine shifted toward an offensive orientation focused on destroying the enemy’s will to fight. The 1949 edition of Operations defined the objective of military operations as the “destruction of the enemy’s armed forces and his will to fight.”^[20] This asymmetry persisted in the 1954 edition, which explicitly introduced psychological operations designed to “lessen the enemy’s will to resist, create dissension and defections in his ranks, and reduce or eliminate the support of civilian populations.”^[21] Notably, the same manual linked combat motivation to narrative and information control, directing that news be “censored with due regard for public support and benefits to troop morale and unit esprit de corps.”^[22]

The Vietnam War, during which unprecedented levels of U.S. military dissent contrasted with the Viet Cong persistence, highlighted the difficulty of assessing or manipulating the will to fight. This, combined with the transition to an all-volunteer force with assumed high levels of combat motivation, may have contributed to the concept’s subsequent disappearance from doctrine.^[23] The absence of the will to fight was reinforced by an increasing focus on technology during and, after the Cold War, reduced the focus to more human elements that are more challenging to quantify. From 1968 to 1986, doctrinal publications omitted explicit discussion of the will to fight. Leadership responsibilities to “protect the force” through cohesion, morale, and information remained, but were framed as tactical imperatives rather than components of a broader motivational capability.^[24] During the transition to an all-volunteer force, the military sponsored research on these internal variables, which later informed modern leadership doctrine, even as the will to fight remained doctrinally absent.^[25]

The 1993 edition of Operations, published after Operation Desert Storm, marked a renewed appreciation for the human dimension of warfare.^[26] The decisive victory—attributed in part to the collapse of the Iraqi will to fight—revived Clausewitz’s assertion that “war is a contest of wills.”^[27] The manual emphasized enemy will as the central focus of combat operations and offered one of doctrine’s few explicit definitions of will: “the disposition to act toward achievement of a desired end state . . . to persevere in the face of all difficulties.”^[28] It further described will as nonlinearly related to combat power, noting that “when will is lacking, so is combat power; when will is strong, it multiplies the effectiveness of military forces.”^[29] This framing acknowledged the emergent and cumulative nature of combat power.

The 1993 edition also recognized the importance of the U.S. will to fight, stating that “Army forces must also be adept and have will to fight in more protracted conflicts if necessary.”^[30] Internal factors, such as cohesion and training, continued to be leader-managed elements of the “human dimension.”^[31] However, the manual identified leadership as the singular source of will without justification and failed to acknowledge that units may demonstrate a will to fight despite poor leadership (or conversely lose it under competent leaders).^[32]

The enduring institutional lesson drawn from the First Gulf War, however, emphasized technological superiority rather than human factors. Subsequent doctrine reflected a bias toward quantifiable and tangible elements of combat power, relegating the will to fight to a secondary consideration. Combat motivation became subordinate to technological advantage, particularly in information systems.^[33] Consequently, the 2001 edition of Operations made only passing reference to the will to fight, noting that enemy forces might use “terrorist tactics and other attacks to erode public support, alliance or coalition cohesion, and the will to fight.”^[34] This limited acknowledgment reinforced the doctrinal tendency to treat American will to fight as effectively inexhaustible.

Beginning in 2016, Clausewitzian language emphasizing war as a human endeavor reemerged in U.S. doctrine, but treatment of the will to fight remained asymmetric. While the term appears 4 times in the 2019 Operations, Army Doctrine Publication (ADP) 3-0, and 18 times in the 2025 edition of the field manual, it remains poorly defined. Operations, FM 3-0, elevates the will to fight as a potential decisive factor and quotes Fleet Admiral Chester W. Nimitz: “The final objective in war is the destruction of the enemy’s capacity and will to fight.”^[35] This offensive framing is reinforced by guidance directing leaders to “do everything possible in the physical and information dimensions to reduce the enemy’s will to fight.”^[36] References to protecting U.S. will to fight are rare and tangential. Current Army doctrine addresses friendly combat motivation only twice, indirectly through the mission of Army bands “to instill in our forces the will to fight and win” and through acknowledgment that disinformation campaigns can reduce morale and will within the United States.^[37] Although cohesion, trust, and alliances are described as components of the “human advantage,” doctrine does not explicitly connect them to the will to fight.^[38]

Joint doctrine follows a similar pattern. Joint Campaigns and Planning, JP 3-0, states that “achieving strategic objectives frequently involves the destruction of the enemies’ capabilities and their will to fight,” but provides no definition or further discussion of the concept.^[39] Joint Planning, JP 5-0, reinforces the importance of the will to fight by incorporating it into discussions of the enemy centers of gravity, defined as “the source of power or strength that enables a military force to achieve its objective.”^[40] While this framing acknowledges the systemic nature of the will to fight, doctrine offers no guidance on identifying, assessing, or protecting the factors that promote or degrade it.^[41] Despite noting that the will to fight can have a “dramatic impact on the joint force’s success,” it remains an intangible consideration rather than an operationalized capability.^[42] U.S. Marine Corps doctrine follows a similar trajectory. Marine Corps Operations, Marine Corps Doctrine Publication (MCDP) 1-0, states that “the ultimate military objective of war is to defeat the enemy’s forces or destroy the will to fight” but offers no definition or analysis.^[43]

In contrast, some partner nations and multinational organizations explicitly incorporate the will to fight into doctrine, treating it as a principle or capability rather than an assumption. The United Kingdom includes “maintenance of morale,” which is closely aligned to the will to fight, as a principle of war. ^[44] Defined as “a positive state of mind derived from inspired political and military leadership, a shared sense of purpose and values, well-being, feeling of worth, and group cohesion,” it is described as “crucial for operational success” and manifests as “staying power and resolve.”^[45] Similarly, North Atlantic Treaty Organization’s (NATO), Allied Joint Doctrine for the Conduct of Operations, Allied Joint Publication 3, identifies “maintenance of morale” as both a principle and operational consideration.^[46] NATO defines will as “based on the unity of communities of interest or armed groups, fighting spirit, morale and cohesion,” noting that once the will to fight is lost, an adversary relinquishes the ability to influence events.^[47] This insight, widely acknowledged in theory, is one that U.S. doctrine recognizes rhetorically but rarely operationalizes in practice.

Theory

Doctrine is not developed in isolation. Broader military theory influences the way militaries conceptualize the will to fight and associated planning. A brief survey of military theory therefore provides essential context for understanding how the current doctrinal imbalance emerged and why the protection of friendly will to fight remains underdeveloped. Military theory has long recognized the will to fight as a decisive element of combat effectiveness. A review of theorists indicates “there are many occurrences when the strength of will was the center of gravity at the operational or even tactical level of war.”^[48] Yet despite this recognition, military theory mirrors doctrinal practice in one critical respect: it overwhelmingly emphasizes how to destroy an adversary’s will while offering comparatively little guidance on how to protect or cultivate one’s own. A survey of military theory thus reveals not a lack of appreciation for the will to fight but a persistent asymmetry in its application. This imbalance helps explain why friendly the will to fight risks treatment as an assumption, rather than as a vulnerable capability requiring deliberate protection.

Although Clausewitz is often considered the foundational authority on will in war, earlier theorists articulated similar insights. Writing in 370 BCE, the Greek commander Xenophon recognized that sustaining morale in combat was imperative.^[49] He rejected the notion that numerical or materiel superiority alone determined victory, arguing instead that success favored those with “stouter hearts” whose adversaries lacked the will to stand against them.^[50] Clausewitz echoed this perspective more than 2,000 years later, asserting that “the moral elements are among the most important in war” and that will is a moral force that animates and directs physical power.^[51] Writing in the late nineteenth century, French Army colonel Ardant du Picq similarly emphasized the primacy of the human element. In Battle Studies: Ancient and Modern Battle, he argued that organization, discipline, and tactics ultimately depend on the “human heart,” lamenting that “it is rarely taken into account; and often strange errors are the result. . . . We must consider it!”^[52]

Throughout the twentieth century, interest in the psychological component of warfare persisted, particularly among theorists focused on land combat. In The Principles of War, French field marshal Ferdinand Foch described defeat not as a product of material forces alone, but as a moral collapse produced by fear and discouragement.^[53] He characterized war as “the domain of moral forces,” victory as “moral superiority,” and battle as “a struggle between two wills.”^[54] Although Foch advocated offensive action to shatter enemy morale through sudden and violent blows, he also stressed the defensive imperative of strengthening one’s own moral force, arguing that an army must “always aim at increasing and strengthening its moral force.”^[55] Similarly, in a 1941 address, U.S. Army Chief of Staff George C. Marshall argued that victory depended less on fighting than on the spirit brought to the fight, identifying morale as the psychological element responsible for success.^[56]

Paralleling doctrinal trends, the emergence of strategic airpower in the twentieth century reinforced a shift toward externally focused theories of will. The ability to strike adversaries at a distance encouraged theorists to prioritize offensive action aimed at degrading enemy morale, often at the expense of considering how to protect or develop one’s own will to fight. Giulio Douhet’s The Command of the Air exemplifies this shift. Although Douhet adopted Clausewitz’s framing of war as a contest of wills, he advocated a purely offensive approach, arguing that bombing population centers would induce sufficient suffering to break national will and compel political capitulation.^[57] Similar logic appears in the work of airpower advocates such as Brigadier General Billy Mitchell, Lord Hugh Montague Trenchard, and Colonel John R. Boyd, all of whom emphasized attacking “vital” or “nerve” centers to achieve “strategic paralysis” and the collapse of the will to fight.^[58] These theories also fail to take into account the inverse or nonlinear effect where increased strategic strikes results in an increase in the will to fight, even if degrading the capability to do so.

This adversary-oriented focus was not limited to airpower theorists. B. H. Liddell Hart argued that decisive victory required destroying an opponent’s “moral equilibrium.”^[59] He asserted that “the chief incalculable is the human will, which manifests itself in resistance,” and that a “willing spirit” was as important as any tangible means.^[60] Like earlier theorists, Liddell Hart acknowledged the intricate relationship between physical and psychological factors and concluded that the moral component was both more vulnerable and more decisive.^[61] While he emphasized movement and surprise as the most effective means of achieving psychological effects, his prescriptions similarly concentrated on attacking enemy morale rather than safeguarding one’s own will to fight.^[62]

The type of direct conflicts the U.S. military entered during the last 75 years served to reinforce the development and persistence of offensive focus on the will to fight. The power and technology differential between the United States and its adversaries allowed planners to be less concerned with strategic strikes targeting population centers and resulting decline in the will to fight. Instances of striking U.S. population centers, such as in Pearl Harbor or 11 September (9/11) have been very rare (and actually served to increase the will to fight). The adversaries the United States has faced during the last half century have generally lacked the capacity for sustained strategic strikes against American forces.

Non-Western theorists also underscore the preeminence of the will to fight, with similar implications for its protection. Sun Tzu viewed physical resistance as an extension of will, emphasizing leadership, discipline, and cohesion as essential to motivating action in combat.^[63] He considered defeating an enemy without physical battle the ideal form of victory, making will a legitimate and decisive military target.^[64] He warned that “an entire enemy army can be demoralized and its commander can be made to lose heart.”^[65] Mao Zedong’s theory of protracted warfare similarly aimed to degrade the national spirit of a stronger adversary over time. General Vo Nguyen Giap operationalized this approach during the Vietnam War, by explicitly targeting the will of the U.S. military and public.^[66] Soviet military thought echoed these perspectives. Field Marshal Georgy Zhukov asserted that “large-scale battles and whole wars are won by troops which have a strong will for victory, clear goals before them, high moral standards, and devotion to the banner under which they go to battle.”^[67] In Afghanistan, Taliban leadership frequently relied on the strategy to sustain resistance until the U.S. political will collapsed, expediting the process with provoking overreaction and deliberate propaganda.^[68]

Modern military thinkers continue to affirm the centrality of the will to fight, with more appreciation of its value on both sides than doctrine currently reflects. A 2018 Rand study characterizes it as “arguably, the single most important factor in war,” and describes military effectiveness as the product of capability and will.^[69] General Norman Schwarzkopf similarly argued that “if you don’t have the will to fight, then, you are not going to have a very good army.”^[70] Former Secretary of Defense general James N. Mattis echoed this view, observing that defeat ultimately befalls the belligerent whose will collapses first.

Examined holistically, military theory demonstrates enduring recognition of the decisive role of the will to fight while simultaneously reinforcing a conceptual imbalance. Will is consistently treated as something to be attacked in the enemy rather than safeguarded within one’s own force. This theoretical tendency, mirrored in doctrine and reinforced by the type of conflicts the United States has engaged in, risks the use of an unacknowledged planning assumption that the U.S. will to fight is durable, self-sustaining, and immune to erosion.

Acknowledging the Assumption

Treating the military will to fight as an assumption unintentionally obscures its vulnerability and limits planners’ ability to design mitigation measures or appropriate branches or sequels. This tendency is not new. At the end of the nineteenth century, Ardant du Picq identified it as a common—and dangerous—error among military professionals. In Battle Studies, he criticized planners for beginning with weapons and technology, while maintaining an unquestioned belief that soldiers would perform exactly as intended.^[71] More than a century later, this error still occurs in modern planning practice. Contemporary analysis reinforces du Picq’s warning. The 2018 Rand study acknowledges the failure to understand and apply will to fight as a “significant vulnerability in US strategy development,” yet it offers little elaboration or practical guidance.^[72]

Relying on a purely offensive strategy to destroy an enemy’s will to fight is increasingly hazardous given the potential nature of future conflict. Future adversaries are increasingly more capable of aerial strikes, drone attacks, or executing strategic events that are likely to degrade military will to fight. Adversaries that lack this ability, particularly those confronting a numerically or technologically superior U.S. force, are likely to find alternative means to target psychological components and the will to fight. In an all-volunteer force, protracted conflict, attrition, and information operations can exert considerable influence on combat motivation. The shift to multidomain operations and great power competition, with its emphasis on technological development, platform parity, and logistics, increases the need to deliberately address the human element of will.^[73] The changes in modern combat may also limit the extent to which previous lessons about the military will to fight in an all-volunteer force can be applied.

A common axiom holds that a planner should not identify problems or challenge assumptions without proposing solutions. The first step in preventing U.S. military will to fight from being an unacknowledged planning assumption is to establish a Joint definition of the will to fight that is deliberately applicable to both friendly and enemy forces. This would facilitate acknowledgment of its bilateral nature, encourage research, and develop an appreciation of the complex nature of the will to fight. The second is to acknowledge that U.S. military will to fight must be protected. This would rebalance the primarily offensive, enemy-focused viewpoint in current doctrine and theory. More importantly, it confronts the presence of U.S. military will to fight as an unacknowledged assumption and facilitates the planning, assessment, and collection associated with planning assumptions. Protecting the military will to fight requires exploration and discussion of options to do so.

Fortunately, the same characteristics that make military will to fight complex offer leverage points for planners at all echelons to protect it. Recognizing will to fight as a finite friendly capability does not require planners to control or more accurately influence it directly. Instead, it enables planners to shape the conditions that influence combat motivation at the operational level. Since the will to fight emerges from a complex adaptive system, operational design provides planners with leverage to potentially preserve and strengthen it. Theory and history suggest that achievable and legitimate objectives, prudent risk acceptance, deliberate manipulation of tempo, and a coherent narrative can protect and amplify combat motivation. Since protective measures are likely to have mixed (and unpredictable) effectiveness, multiple strategies may be beneficial.

While beyond the scope of military planners, national will to fight merits discussion because of its influential relationship with military will to fight and the interplay between the two forces. Rand defines national will to fight as a government’s determination to sustain operations despite declining prospects and rising costs.^[74] Typically, the national and military will to fight have a corresponding, reinforcing relationship. Operational success can bolster public support, while societal commitment strengthens military morale at all echelons.^[75] Public support enhances military morale, recruiting, and tolerance for risk.^[76] National combat motivation directly affects military operations through its influence on morale, recruiting, and tolerance for risk, extended duration, and casualties.^[77] In fact, public support is sufficiently consequential that some theorists advocate adding it as a principle of war.^[78] Declining public support during the Vietnam War correlated with discipline problems and a diminished sense of purpose among troops.^[79] Expectations shaped by Operation Desert Storm may have further eroded public tolerance for casualties in a future great power conflict, increasing the importance of protecting the will to fight.^[80] Given the importance and influence of the national will to fight, it is important to recognize the limitations of military planners, especially at the operational level. While some mitigation may be possible, planners cannot compensate for all fluctuations or shortcomings in the national will to fight.

Designing Protection Operations

Objective

The objective, or end state, of an operation is one of the most powerful determinants of the will to fight, shaping both expectations of success and tolerance for sacrifice. Joint Planning, JP 5-0, defines the objective as “a clearly defined and achievable aim toward which an operation is directed.”^[81] An end state with these characteristics promotes unity of effort and reduces risk.^[82] When personnel perceive an objective as achievable, the will to fight increases. Clausewitz observed that “the desire for peace on either side will rise and fall with the probability of further successes and the amount of effort these would require.”^[83] Accordingly, planners must ensure objectives are contextually realistic. British field marshal Sir William Slim reinforced this relationship in Defeat into Victory, noting that soldiers must believe not only that the objective is attainable but that the organization pursuing it is competent and effective.^[84] This can be done at echelon, even if higher objectives are ambiguous or undefined.

Clarity further enhances the protective value of the objective. The sacrifices an organization is willing to accept, both in magnitude and duration, depend on the perceived value of the objective and the precision with which it is articulated.^[85] A clearly defined enemy promotes cohesion and unity of effort at both the military and national levels.^[86] Without this clarity, Operations, ADP 3-0, warns that missions lose focus and purpose.^[87] Modern conflict complicates this requirement. Nonstate actors, nonattributional actions, and competition below the level of armed conflict obscure enemy identification, as experienced in Afghanistan, Korea, and Vietnam. As political scientist John E. Mueller notes, compared to World War II, modern adversaries appear less morally distinct, progress is harder to measure, and war termination is often ambiguous.^[88] Operational clarity may be easier to achieve than strategic but efforts should be made for them to be nested and consistent.

Legitimacy, or casus belli, further shapes the will to fight. Joint Planning, JP 5-0, describes legitimacy as a “key factor, based on the actual and perceived legality, morality, and rightness of the actions from the various perspectives of relevant actors, stakeholders, and other interested audiences.”^[89] Planners can influence both cognitive legitimacy, or feasibility, and normative legitimacy, defined as the perceived value of the objective relative to its costs.^[90] Ideology plays a central role in normative legitimacy. As Slim argued, a worthy cause must be positive and compelling, not merely defensive or oppositional.^[91] Legitimacy increases when an organization perceives a direct threat to something it values, such as territory or ideals.^[92] When national war aims are clear and imminent, military and society tend to unify; when aims are diffuse or ambiguous, cohesion erodes.^[93] Clausewitz emphasized that powerful and inspiring motives align political and military objectives and intensify commitment.^[94] A clearly defined, ideologically aligned objective is therefore among the most effective levers for sustaining the will to fight.

The role of ideology calls for particular attention in an all-volunteer force. Popular narratives that emphasize fighting solely for comradeship are insufficient.^[95] While interpersonal loyalty and unit cohesion matter, research suggests that modern soldiers are educated, reflective and motivated by ideological commitments.^[96] Studies of the Iraq War (2003–11) indicate that freedom, democracy, and liberty remain salient motivators.^[97] Reliance on “brotherhood” alone ignores the heterogeneity of the force and the social independence of today’s soldiers.^[98] Enabled by technology, modern servicemembers maintain identities more independent from their military service than earlier generations. As a result, aligning the military end state with organizational identity is critical to strengthening combat motivation.

Alliances and international organizations further enhance legitimacy. Rand finds that strong allies improve a state’s ability to sustain combat through shared resources and increased confidence.^[99] While establishment of these relationships occurs at high echelons, operational planners can influence how effectively allies and partners are integrated into operations. Exercising and integrating bilateral relationships and coalition partners can strengthen legitimacy.^[100] Coalition warfare and United Nations’ authorization increase public support, as demonstrated during the First Gulf War.^[101] General Schwarzkopf recognized this, noting that “we had no less than nine United Nations resolutions authorizing our actions, and we had the support of virtually the entire world.” The resolutions “provided the legal basis for our military operations in the Gulf” and “were clear in their intent: kick the Iraqi military force out of Kuwait.”^[102] As operations shift toward theaters with fewer traditional allies, legitimacy and clarity of the end state become even more critical.^[103]

The legitimacy, feasibility, and partnered nature of an operational objective has the potential to influence national will to fight by influencing public perception of these components within the overall war effort. These events are often unpredictable and have varied impact on the military will to fight. Extreme, highly publicized events, such as My Lai Massacre (1968) or the Battle of Mogadishu (1993), had direct degrading impact on the national will to fight and only an indirect, time-lagged impact on military will to fight.^[104] The Tet Offensive, and more importantly, the U.S. response to it, impacted both nation and military will to fight. At the national and military levels, it increased disillusionment and confidence in the ability to achieve military and nation objectives and degraded confidence in leadership.^[105] For a positive example, Operation Neptune Spear in 2011, the killing of Osama bin Laden in Pakistan, positively increased both national and military will.^[106] Given the potential for implications on the national and military will to fight, it is helpful for planner to acknowledge what General Frederick C. Weyand observed: “when the Army is committed the American people are committed, when the American people lose their commitment, it is futile to try to keep the Army committed.”^[107]

Risk

To achieve a clearly defined objective, planners must accept prudent risk while mitigating events that degrade combat motivation. Joint Planning defines risk as “the probability and consequence of an event causing harm to something valued.”^[108] The relationship between casualties and the military will to fight is complex. In some cases, losses increase friendly resolve; in others, they strengthen enemy determination and undermine legitimacy. Unexpected losses degrade the will to fight more rapidly than predicted losses of equal magnitude. A study of the Korean and Vietnam Wars found that each time U.S. casualties increased by a factor of 10, popular support declined by approximately 15 percentage points.^[109] With great power competition, high casualty rates pose a central risk, with attrition inversely affecting U.S. willingness to fight. After decades of asymmetric conflict, U.S. forces and the American public have become unaccustomed to high attrition, making risk aversion the norm. Future conflicts are unlikely to permit delayed entry, proxy warfare, or reliance on standoff capabilities. High early casualties may be especially damaging to an all-volunteer force. As researcher Emma Moore notes, it is now reasonable to question “whether a highly professional, voluntary, innovative military can overcome huge losses and remain an effective fighting force.”^[110]

Once significant attrition occurs, rotation and replacement policies become critical. Research indicates that rotating larger cohesive units preserves morale more effectively than individual replacements.^[111] Defense analyst Anthony Kellett found that during the Korean and Vietnam Wars, the arrival of individual replacements, especially immediately before or during combat, had “a negative effect on the group psyche and cohesion.”^[112] Predictable rotation schedules provided soldiers with achievable goals and preserve the will to fight.^[113] This finding echoes du Picq’s insistence on maintaining stable combat groups so that “comrades in peacetime maneuvers shall be comrades in war.”^[114]

Tempo

Tempo, defined by Operations as “the relative speed and rhythm of military operations over time with respect to the enemy,” shapes the will to fight and creates opportunity for surprise.^[115] Former Army planner Robert R. Leonhard elaborates that the temporal characteristics of war include duration, frequency, sequence, and opportunity.^[116] These factors are interdependent and mutually reinforcing, with the potential to both influence and be influenced by will to fight. Unsurprisingly, high operational frequency (defined as the number of engagements, maneuvers, or operations that occur per unit of time) risks institutional fatigue and strains coalition cohesion. As Leonhard summarizes, “frequency can threaten disintegration of a military or political establishment.”^[117] Similarly, extremely low frequency, or extended periods of time without any events, can cause a decline the military will to fight. Elevated levels of combat motivation may shorten conflict duration by increasing the intensity and effectiveness of combat. Planners may be able to modulate temporal characteristics to impact duration, overall risk and intensity and indirectly influence the will to fight. As Clausewitz observed, tempo and objective are closely related, with the willingness to sustain effort dependent on perceived legitimacy and ideological alignment. Wars with vague or incoherent ideology tend to be “among the bloodiest and longest in history.”^[118]

Planners should think in terms of available time and how best to use it, rather than designing an operation and then assessing how long it will take.^[119] This is due in part to the impact operational tempo can have on the national will to fight and vice versa. The U.S. public favors short wars with visible, measurable progress.^[120] As duration extends without perceptible progress, individual and collective meaning erodes, accelerating declines in both national and military will to fight. Historically, U.S. conflicts against state actors have been relatively brief, with Vietnam as a notable exception. Protracted wars tend to favor the defenders, increase uncertainty, and invite disinformation.^[121] Extended conflicts also allow adversaries to adapt, develop new tactics, and exploit time. Mao’s theory of protracted war underscores this risk.^[122] Prior to China’s entry into the Korean War, U.S. public support for the war was relatively high, correlating with expectations of a short conflict.^[123] When the war “dragged on with seemingly no conclusion in sight,” U.S. combat motivation eroded.^[124] Time available to planners may also be influenced by election cycles and the desire for candidates to show progress to their constituents.

Narrative

Operational design alone is insufficient to protect the will to fight without a coherent narrative that translates plans into meaning. Narrative links objective, risk, and tempo to purpose, potentially shaping both national and military will to fight. Internal to the military, narrative enables soldiers to understand why they fight and how their actions contribute to success. Externally, it sustains national will to fight by reducing civil-military distance and legitimizing continued effort.

Information strengthens morale by shaping perception. Soldiers should understand the desired end state, expected duration, and associated risks of an operation.^[125] British field marshal Bernard Law Montgomery argued that “every single soldier must know, before he goes into battle, how the little battle he is to fight fits into the larger picture.”^[126] General Viscount Slim institutionalized this principle through “Information Rooms,” that displayed operational orders, intelligence reports, and news from home and were open to all ranks. Slim credited these rooms with improved performance by fostering trust, awareness, and inclusion.^[127]

Conversely, information gaps breed rumor and pessimism, degrading morale and combat motivation.^[128] Soldier and organization motivation is complex and related to the shared ideology of the objective ^[129] Reflecting on World War II, General William C. Westmoreland argued that the U.S. Army often failed to provide soldiers with sufficient information to justify the risks they were asked to assume.^[130] During the Korean War, infantrymen frequently expressed frustration over their limited situational awareness, often overestimating enemy strength.^[131] This pattern is not new. During the 1862 Peninsular Campaign, Union forces consistently overestimated Confederate numbers, contributing to operational paralysis.^[132] As Clausewitz observed, in the absence of reliable information, “men are always more inclined to pitch their estimate of the enemy’s strength too high than too low.”^[133]

Effective narratives therefore communicate purpose, duration, and ideological justification for risk. When Army leaders concluded that traditional lectures failed to motivate disengaged troops, Army Chief of Staff general George C. Marshall commissioned filmmaker Frank Capra to produce a
seven-part documentary series explaining “why we are fighting, and the principles for which we are fighting.”^[134] Similarly, when General Matthew B. Ridgway assumed command of the Eighth Army in Korea, he restored combat motivation by reasserting control of the narrative. His widely distributed memorandum addressed the questions of “Why are we here?” and “What are we fighting for?”—clarity that proved instrumental in stabilizing morale.^[135]

In the modern environment of rapid information exchange, military and national narrative are impossible to separate. Therefore, planners should make efforts for consistent messaging at all echelons and to the public. When planning public affairs, it is also helpful to remember that as historian John Lewis Gaddis notes, there is growing “disconnection between the security to which we’ve become accustomed and the means by which we obtained it.”^[136] This gap has widened as public familiarity with the military has declined, fatigue from the Global War on Terrorism has set in, and the force has become increasingly socially isolated.^[137] A coherent external narrative can mitigate these trends by fostering legitimacy, understanding, and shared responsibility.

Regardless of audience, narrative must remain truthful to be credible. Exposure of deception or fabrication rapidly undermines both military and national will. Cultivating the will to fight does not require manipulation, but clear articulation of objectives, rationale, and anticipated duration.^[138] Coherent narratives also counter to adversary disinformation.^[139] Since public attention naturally declines over time, narrative construction must be continuous and adaptive, incorporating plans for sustainment and reengagement.^[140] As Kellett observed, a soldier’s will to fight erodes not only from battlefield hardship, but from “his sense of war-weariness or of flagging support at home.”^[141]

The Korean War illustrates the consequences of narrative failure. Initial U.S. involvement was clearly justified: supporting South Korea against North Korean aggression within a legitimate international framework. As the war progressed, however, the United States failed to define a clear military end state or even an identifiable enemy. Both soldiers and civilians struggled to justify the continued sacrifice. The father of Private Kenneth R. Shadrick, the first U.S. soldier killed in Korea, could only conclude that his son was “fighting against some kind of government.”^[142] Elevated risk and mounting casualties, absent a coherent and credible narrative, accelerated the collapse of the will to fight. In this case, narrative failure did not merely fail to protect combat motivation, but rather actively hastened its erosion.

Conclusion

Military will to fight, defined here as the cognitive capacity to engage in and sustain combat operations in pursuit of a unit’s mission, is neither permanent nor inexhaustible. However, without a doctrinal definition and the primarily offensive focus in doctrine, theory, and practice, there is a propensity for the presence of U.S. military will to fight to be an unacknowledged assumption. Allow it to remain as such constitutes a systemic vulnerability in military planning. When the military will to fight is instead recognized and defined as a critical friendly capability, planners can deliberately design operations to preserve and strengthen it. Relying primarily on the destruction of enemy will as a proxy for protecting U.S. combat motivation is insufficient in modern warfare, particularly against adversaries that deliberately target psychological vulnerabilities or are capable of inflicting large numbers of casualties.

Although military theory and doctrine consistently affirm the importance of the will to fight, this recognition has not translated into commensurate understanding or institutional emphasis. U.S. doctrine neither defines the concept nor provides meaningful guidance for its protection. Instead, military thought and resourcing continue to favor quantifiable and technological components of combat power. This bias has contributed to a poor historical record of assessing and safeguarding the will to fight and has reinforced a doctrinal emphasis on eroding enemy motivation rather than protecting U.S. combat motivation. Future adversaries are likely to exploit this imbalance by targeting the psychological resilience of both the force and the population.

If planners are willing to acknowledge the military will to fight as an assumption rather than a guarantee, operational design offers practical mechanisms for its preservation at the operational level. Clear, achievable, and ideologically aligned objectives increase combat motivation, particularly when reinforced by legitimacy derived from allies, partners, and a clearly defined enemy. Risk must be deliberately managed and communicated, especially given the attrition probable in great power competition. Tempo, particularly duration and frequency, also exerts a powerful influence. Shorter more decisive conflicts tend to preserve higher levels of the will to fight, while protracted operations erode it.

Equally important is the reinforcing relationship between military and national will, mediated through narrative. Military and national will are mutually supporting; degradation of one accelerates the erosion of the other. Information is essential to sustaining both. When individuals understand how their sacrifices contribute to a meaningful objective, will is strengthened; when information is absent, rumors and pessimism fill the void. Effective narratives must therefore be coherent, truthful, and sustained over time.

Protecting the military will to fight is neither simple nor guaranteed. As Clausewitz observed, “one must marvel at the fact that heart and strength do not give out more often, and at the way in which the power of an idea can, by its lasting effect, summon up and support incredible exertions in human beings.”^[143] That endurance however, is not automatic. By rejecting the assumption that the will to fight is inherent and deliberately incorporating its protection into planning and operational design, the U.S. military can better preserve the human foundation necessary to fight and win the nation’s wars.