What Did James Mattis Mean by “Lethality?”

Then-Lt. Gen. James Mattis, commander of U.S. Marine Corps Forces, Central Command, speaks to Marines with Marine Wing Support Group 27, in Al Asad, Iraq, in May 2006. [Photo: Cpl. Zachary Dyer]

Ever since publication of the U.S. National Defense Strategy by then-Secretary of Defense James Mattis’s Defense Department in early 2018 made the term “lethality” a foundational principle, there has been an open-ended discussion as to what the term actually means.

In his recent memoir, co-written with Bing West, Call Sign Chaos: Learning to Lead (Random House, 2019), Mattis offered his own definition of lethality. Sort of.

At the beginning of Chapter 17 (pages 235-236), he wrote (emphasis added):


History presents many examples of militaries that forgot that their purpose was to fight and win. So long as we live in an imperfect world, one containing enemies of democracy, we will need a military strictly committed to combat-effectiveness. Our liberal democracy must be protected by a bodyguard of lethal warriors, organized, trained, and equipped to dominate in battle.

The need for lethality must be the measuring stick against which we evaluate the efficacy of our military. By aligning the entire military enterprise—recruiting, training, educating, equipping, and promoting—to the goal of compounding lethality, we best deter adversaries, or if conflict occurs, win at lowest cost to our troops’ lives. …

While not defining lethality explicitly, it would appear that Mattis equates it with “combat-effectiveness,” which he also does not explicitly define, but seems to mean as the ability “to dominate in battle.” It would seem that Mattis understands lethality not as the destructive quality of a weapon or weapon system, but as the performance of troops in combat.

More than once he also refers to lethality as a metric, which suggests that it can be quantified and measured, perhaps in terms of organization, training, and equipment. It is likely Mattis would object to that interpretation, however, given his hostility to Effects Based Operations (EBO), as implemented by U.S. Joint Forces Command, before he banned the concept from joint doctrine in 2008, as he related on pages 179-181 in Call Sign Chaos.

Trevor Dupuy’s Definitions of Lethality

Two U.S. Marines with a M1919A4 machine gun on Roi-Namur Island in the Marshall Islands during World War II. [Wikimedia]

It appears that discussion of the meaning of lethality, as related to the use of the term in the 2018 U.S. National Defense Strategy document, has sparked up again. It was kicked off by an interesting piece by Olivia Gerard in The Strategy Bridge last autumn, “Lethality: An Inquiry.

Gerard credited Trevor Dupuy and his colleagues at the Historical Evaluation Research Organization (HERO) with codifying “the military appropriation of the concept” of lethality, which was defined as: “the inherent capability of a given weapon to kill personnel or make materiel ineffective in a given period, where capability includes the factors of weapon range, rate of fire, accuracy, radius of effects, and battlefield mobility.”

It is gratifying for Gerard to attribute this to Dupuy and HERO, but some clarification is needed. The definition she quoted was, in fact, one provided to HERO for the purposes of a study sponsored by the Advanced Tactics Project (AVTAC) of the U.S. Army Combat Developments Command. The 1964 study report, Historical Trends Related to Weapon Lethality, provided the starting point for Dupuy’s subsequent theorizing about combat.

In his own works, Dupuy used a simpler definition of lethality:

He also used the terms lethality and firepower interchangeably in his writings. The wording of the original 1964 AVTAC definition tracks closely with the lethality scoring methodology Dupuy and his HERO colleagues developed for the study, known as the Theoretical Lethality Index/Operational Lethality Index (TLI/OLI). The original purpose of this construct was to permit some measurement of lethality by which weapons could be compared to each other (TLI), and to each other through history (OLI). It worked well enough that he incorporated it into his combat models, the Quantified Judgement Model (QJM) and Tactical Numerical Deterministic Model (TNDM).

What Does Lethality Mean In Warfare?

In an insightful essay over at The Strategy Bridge, “Lethality: An Inquiry,” Marine Corps officer Olivia Gerard accomplishes one of the most important, yet most often overlooked, aspects of successfully thinking about and planning for war: questioning a basic assumption. She achieves this by posing a simple question: “What is lethality?”

Gerard notes that the current U.S. National Defense Strategy is predicated on lethality; as it states: “A more lethal, resilient, and rapidly innovating Joint Force, combined with a robust constellation of allies and partners, will sustain American influence and ensure favorable balances of power that safeguard the free and open international order.” She also identifies the linkage in the strategy between lethality and deterrence via a supporting statement from Deputy Secretary of Defense Patrick Shanahan: “Everything we do is geared toward one goal: maximizing lethality. A lethal force is the strongest deterrent to war.”

After pointing out that the strategy does not define the concept of lethality, Gerard responds to Shanahan’s statement by asking “why?”

She uses this as a jumping off point to examine the meaning of lethality in warfare. Starting from the traditional understanding of lethality as a tactical concept, Gerard walks through the way it has been understood historically. From this, she formulates a construct for understanding the relationship between lethality and strategy:

Organizational lethality emerges from tactical lethality that is institutionally codified. Tactical lethality is nested within organizational lethality, which is nested within strategic lethality. Plugging these terms into an implicit calculus, we can rewrite strategic lethality as the efficacy with which we can form intentional deadly relationships towards targets that can be actualized towards political ends.

To this, Gerard appends two interesting caveats: “Notice first that the organizational component becomes implicit. What remains outside, however, is the intention–a meta-intention–to form these potential deadly relationships in the first place.”

It is the second of these caveats—the intent to connect lethality to a strategic end—that informs Gerard’s conclusion. While the National Defense Strategy does not define the term, she observes that by explicitly leveraging the threat to use lethality to bolster deterrence, it supplies the necessary credibility needed to make deterrence viable. “Proclaiming lethality a core tenet, especially in a public strategic document, is the communication of the threat.”

Gerard’s exploration of lethality and her proposed framework for understanding it provide a very useful way of thinking about the way it relates to warfare. It is definitely worth your time to read.

What might be just as interesting, however, are the caveats to her construct because they encompass a lot of what is problematic about the way the U.S. military thinks—explicitly and implicitly—about tactical lethality and how it is codified into concepts of organizational lethality. (While I have touched on some of those already, Gerard gives more to reflect on. More on that later.)

Gerard also references the definition of lethality Trevor Dupuy developed for his 1964 study of historical trends in weapon lethality. While noting that his definition was too narrow for the purposes of her inquiry, the historical relationship between lethality, casualties, and dispersion on the battlefield Dupuy found in that study formed the basis for his subsequent theories of warfare and models of combat. (I will write more about those in the future as well.)

Should The Marines Take Responsibility For Counterinsurgency?

United States Marines in Nacaragua with the captured flag of Augusto César Sandino, 1932. [Wikipedia]

Sydney J. Freedberg, Jr recently reported in Breaking Defense that the Senate Armed Services Committee (SASC), led by chairman Senator John McCain, has asked Defense Secretary James Mattis to report on progress toward preparing the U.S. armed services to carry out the recently published National Defense Strategy oriented toward potential Great Power conflict.

Among a series of questions that challenge existing service roles and missions, Freedberg reported that the SASC wants to know if responsibility for carrying out “low-intensity missions,” such as counterinsurgency, should be the primary responsibility of one service:

Make the Marines a counterinsurgency force? The Senate starts by asking whether the military “would benefit from having one Armed Force dedicated primarily to low-intensity missions, thereby enabling the other Armed Forces to focus more exclusively on advanced peer competitors.” It quickly becomes clear that “one Armed Force” means “the Marines.” The bill questions the Army’s new Security Force Assistance Brigades (SFABs) and suggest shifting that role to the Marines. It also questions the survivability of Navy-Marine flotillas in the face of long-range sensors and precision missiles — so-called Anti-Access/Area Denial (A2/AD) systems — and asked whether the Marines’ core mission, “amphibious forced entry operations,” should even “remain an enduring mission for the joint force” given the difficulties. It suggests replacing large-deck amphibious ships, which carry both Marine aircraft and landing forces, with small aircraft carriers that could carry “larger numbers of more diverse strike aircraft” (but not amphibious vehicles or landing craft). Separate provisions of the bill restrict spending on the current Amphibious Assault Vehicle (Sec. 221) and the future Amphibious Combat Vehicle (Sec. 128) until the Pentagon addresses the viability of amphibious landings.

This proposed change would drastically shift the U.S. Marine Corps’ existing role and missions, something that will inevitably generate political and institutional resistance. Deemphasizing the ability to execute amphibious forced entry operations would be both a difficult strategic choice and an unpalatable political decision to fundamentally alter the Marine Corps’ institutional identity. Amphibious warfare has defined the Marines since the 1920s. It would, however, be a concession to the reality that technological change is driving the evolving character of warfare.

Perhaps This Is Not A Crazy Idea After All

The Marine Corps also has a long history with so-called “small wars”: contingency operations and counterinsurgencies. Tasking the Marines as the proponents for low-intensity conflict would help alleviate one of the basic conundrums facing U.S. land power: the U.S. Army’s inability to optimize its force structure due to the strategic need to be prepared to wage both low-intensity conflict and conventional combined arms warfare against peer or near peer adversaries. The capabilities needed for waging each type of conflict are diverging, and continuing to field a general purpose force is running an increasing risk of creating an Army dangerously ill-suited for either. Giving the Marine Corps responsibility for low-intensity conflict would permit the Army to optimize most of its force structure for combined arms warfare, which poses the most significant threat to American national security (even if it less likely than potential future low-intensity conflicts).

Making the Marines the lead for low-intensity conflict would also play to another bulwark of its institutional identity, as the world’s premier light infantry force (“Every Marine is a rifleman”). Even as light infantry becomes increasingly vulnerable on modern battlefields dominated by the lethality of long-range precision firepower, its importance for providing mass in irregular warfare remains undiminished. Technology has yet to solve the need for large numbers of “boots on the ground” in counterinsurgency.

The crucial role of manpower in counterinsurgency makes it somewhat short-sighted to follow through with the SASC’s suggestions to eliminate the Army’s new Security Force Assistance Brigades (SFABs) and to reorient Special Operations Forces (SOF) toward support for high-intensity conflict. As recent, so-called “hybrid warfare” conflicts in Lebanon and the Ukraine have demonstrated, future battlefields will likely involve a mix of combined arms and low-intensity warfare. It would be risky to assume that Marine Corps’ light infantry, as capable as they are, could tackle all of these challenges alone.

Giving the Marines responsibility for low-intensity conflict would not likely require a drastic change in force structure. Marines could continue to emphasize sea mobility and littoral warfare in circumstances other than forced entry. Giving up the existing large-deck amphibious landing ships would be a tough concession, admittedly, one that would likely reduce the Marines’ effectiveness in responding to contingencies.

It is not likely that a change as big as this will be possible without a protracted political and institutional fight. But fresh thinking and drastic changes in the U.S.’s approach to warfare are going to be necessary to effectively address both near and long-term strategic challenges.

Senate Armed Service Committee Proposes Far-Reaching Changes To U.S. Military

Senate Armed Services Committee members (L-R) Sen. James Inhofe (R-OK), Chairman John McCain (R-AZ) and ranking member Sen. Jack Reed (R-RI) listen to testimony in the Dirksen Senate Office Building on Capitol Hill July 11, 2017 in Washington, D.C. [CREDIT: Chip Somodevilla—Getty Images]

In an article in Breaking Defense last week, Sydney J. Freedberg, Jr. pointed out that the Senate Armed Services Committee (SASC) has requested that Secretary of Defense James Mattis report back by 1 February 2019 on what amounts to “the most sweeping reevaluation of the military in 30 years, with tough questions for all four armed services but especially the Marine Corps.”

Freedberg identified SASC chairman Senator John McCain as the motivating element behind the report, which is part of the draft 2019 National Defense Authorization Act. It emphasizes the initiative to reorient the U.S. military away from its nearly two-decade long focus on counterinsurgency and counterterrorism to prioritizing preparation for potential future Great Power conflict, as outlined in Mattis’s recently published National Defense Strategy. McCain sees this shift taking place far too slowly according to Freedberg, who hints that Mattis shares this concern.

While the SASC request addresses some technological issues, its real focus is on redefining the priorities, missions, and force structures of the armed forces (including special operations forces) in the context of the National Defense Strategy.

The changes it seeks are drastic. According to Freedberg, among the difficult questions it poses are:

  • Make the Marines a counterinsurgency force? [This would greatly help alleviate the U.S. Army’s current strategic conundrum]
  • Make the Army heavier, with fewer helicopters?
  • Refocus Special Operations against Russia and China?
  • Rely less on stealth aircraft and more on drones?

Each of these questions relates directly to trends associated with the multi-domain battle and operations concepts the U.S. armed services are currently jointly developing in response to threats posed by Russian, Chinese, and Iranian military advances.

It is clear that the SASC believes that difficult choices with far-reaching consequences are needed to adequately prepare to meet these challenges. The armed services have been historically resistant to changes involving trade-offs, however, especially ones that touch on service budgets and roles and missions. It seems likely that more than a report will be needed to push through changes deemed necessary by the Senate Armed Services Committee chairman and the Secretary of Defense.

Read more of Freedberg’s article here.

The draft 2019 National Defense Authorization Act can be found here, and the SASC questions can be found in Section 1041 beginning on page 478.