Dupuy’s Verities: The Requirements For Successful Defense

A Sherman tank of the U.S. Army 9th Armored Division heads into action against the advancing Germans during the Battle of the Bulge. {Warfare History Network]

The eighth of Trevor Dupuy’s Timeless Verities of Combat is:

Successful defense requires depth and reserves.

From Understanding War (1987):

Successful defense requires depth and reserves. It has been asserted that outnumbered military forces cannot afford to withhold valuable firepower from ongoing defensive operations and keep it idle in reserve posture. History demonstrates that this is specious logic, and that linear defense is disastrously vulnerable. Napoleon’s crossing of the Po in his first campaign in 1796 is perhaps the classic demonstration of the fallacy of linear (or cordon) defense.

The defender may have all of his firepower committed to the anticipated operational area, but the attacker’s advantage in having the initiative can always render much of that defensive firepower useless. Anyone who suggests that modern technology will facilitate the shifting of engaged firepower in battle overlooks three considerations: (a) the attacker can inhibit or prevent such movement by both direct and indirect means, (b) a defender engaged in a fruitless firefight against limited attacks by numerically inferior attackers is neither physically nor psychologically attuned to making lateral movements even if the enemy does not prevent or inhibit it, and (c) withdrawal of forces from the line (even if possible) provides an alert attacker with an opportunity for shifting the thrust of his offensive to the newly created gap in the defenses.

Napoleon recognized that hard-fought combat is usually won by the side committing the last reserves. Marengo, Borodino, and Ligny are typical examples of Napoleonic victories that demonstrated the importance of having resources available to tip the scales. His two greatest defeats, Leipzig and Waterloo, were suffered because his enemies still had reserves after his were all committed. The importance of committing the last reserves was demonstrated with particular poignancy at Antietam in the American Civil War. In World War II there is no better example than that of Kursk. [pp. 5-6]

Dupuy’s observations about the need for depth and reserves for a successful defense take on even greater current salience in light of the probably character of the near-future battlefield. Terrain lost by an unsuccessful defense may be extremely difficult to regain under prevailing circumstances.

The interaction of increasing weapon lethality and the operational and human circumstantial variables of combat continue to drive the long-term trend in dispersion of combat forces in frontage and depth.

Long-range precision firepower, ubiquitous battlefield reconnaissance and surveillance, and the effectiveness of cyber and information operations will make massing of forces and operational maneuver risky affairs.

As during the Cold War, the stability of alliances may depend on a willingness to defend forward in the teeth of effective anti-access/area denial (A2/AD) regimes that will make the strategic and operational deployment of reserves risky as well. The successful suppression of A2/AD networks might court a nuclear response, however.

Finding an effective solution for enabling a successful defense-in-depth in the future will be a task of great difficulty.

Some Useful Resources for Post-World War II U.S. Army Doctrine Development

This list originated in response to a Twitter query discussing the history of post-World War II U.S. Army doctrine development. It is hardly exhaustive but it does include titles and resources that may not be widely known.

The first two are books:

Benjamin Jensen, Forging the Sword: Doctrinal Change in the U.S. Army (Stanford University Press, 2016)

Jensen focused on the institutional processes shaping the Army’s continual post-war World War II efforts to reform its doctrine in response to changes in the character of modern warfare.

Shimon Naveh, In Pursuit of Military Excellence: The Evolution of Operational Theory (Routledge, 1997)

In an excellent overview of the evolution of operational thought through the 20th century, Naveh devoted two chapters to the Army’s transition to Active Defense in the 70s and then to AirLand Battle in the 80s.

There are several interesting monographs that are available online:

Andrew J. Bacevich, The Pentomic Era: The U.S. Army Between Korea and Vietnam (NDU Press, 1986)

Paul Herbert, Deciding What Has to Be Done: General William E. DePuy and the 1976 Edition of FM 100-5, Operations (Combat Studies Institute, 1988)

John Romjue, From Active Defense to AirLand Battle: the Development of Army Doctrine 1973-1982 (TRADOC, 1984)

John Romjue, The Army of Excellence: The Development of the 1980s Army (TRADOC, 1997)

John Romjue, American Army Doctrine for the Post-Cold War (TRADOC, 1997)

A really useful place to browse is the Army Command and General Staff College’s online Skelton Combined Arms Research Library (CARL). It is loaded with old manuals and student papers and theses addressing a wide variety of topics related to the nuts and bolts of doctrine.

Another good place to browse is the Defense Technical Information Center (DTIC), which is a huge digital library of government sponsored research. I recommend searches on publications by the Army’s defunct operations research organizations: Operations Research Office (ORO), Research Analysis Corporation (RAC), and the Special Operations Research Office (SORO). The Combat Operations Research Group (CORG), particularly a series of studies of Army force structure from squads to theater HQ’s by Virgil Ney. There is much more to find in DTIC.

Two other excellent places to browse for material on doctrine are the Combat Studies Institute Press publications on CARL and the U.S. Army Center of Military History’s publications.

Some journals with useful research include the Journal of Cold War Studies and the Journal of Strategic Studies.

If anyone else has suggestions, let me know.

Active Defense, Forward Defense, and A2/AD in Eastern Europe

The current military and anti-access/area denial situation in Eastern Europe. [Map and overlay derived from situation map by Thomas C. Thielen (@noclador) https://twitter.com/noclador/status/1079999716333703168; and Ian Williams, “The Russia – NATO A2AD Environment,” Missile Threat, Center for Strategic and International Studies, published January 3, 2017, last modified November 29, 2018, https://missilethreat.csis.org/russia-nato-a2ad-environment/]

In an article published by West Point’s Modern War Institute last month, The US Army is Wrong on Future War,” Nathan Jennings, Amos Fox and Adam Taliaferro laid out a detailed argument that current and near-future political, strategic, and operational realities augur against the Army’s current doctrinal conceptualization for Multi-Domain Operations (MDO).

[T]he US Army is mistakenly structuring for offensive clashes of mass and scale reminiscent of 1944 while competitors like Russia and China have adapted to twenty-first-century reality. This new paradigm—which favors fait accompli acquisitions, projection from sovereign sanctuary, and indirect proxy wars—combines incremental military actions with weaponized political, informational, and economic agendas under the protection of nuclear-fires complexes to advance territorial influence…

These factors suggest, cumulatively, that the advantage in military confrontation between great powers has decisively shifted to those that combine strategic offense with tactical defense.

As a consequence, the authors suggested that “the US Army should recognize the evolved character of modern warfare and embrace strategies that establish forward positions of advantage in contested areas like Eastern Europe and the South China Sea. This means reorganizing its current maneuver-centric structure into a fires-dominant force with robust capacity to defend in depth.”

Forward Defense, Active Defense, and AirLand Battle

To illustrate their thinking, Jennings, Fox, and Taliaferro invoked a specific historical example:

This strategic realignment should begin with adopting an approach more reminiscent of the US Army’s Active Defense doctrine of the 1970s than the vaunted AirLand Battle concept of the 1980s. While many distain (sic) Active Defense for running counter to institutional culture, it clearly recognized the primacy of the combined-arms defense in depth with supporting joint fires in the nuclear era. The concept’s elevation of the sciences of terrain and weaponry at scale—rather than today’s cult of the offense—is better suited to the current strategic environment. More importantly, this methodology would enable stated political aims to prevent adversary aggression rather than to invade their home territory.

In the article’s comments, many pushed back against reviving Active Defense thinking, which has apparently become indelibly tarred with the derisive criticism that led to its replacement by AirLand Battle in the 1980s. As the authors gently noted, much of this resistance stemmed from the perceptions of Army critics that Active Defense was passive and defensively-oriented, overly focused on firepower, and suspicions that it derived from operations research analysts reducing warfare and combat to a mathematical “battle calculus.”

While AirLand Battle has been justly lauded for enabling U.S. military success against Iraq in 1990-91 and 2003 (a third-rank, non-nuclear power it should be noted), it always elided the fundamental question of whether conventional deep strikes and operational maneuver into the territory of the Soviet Union’s Eastern European Warsaw Pact allies—and potentially the Soviet Union itself—would have triggered a nuclear response. The criticism of Active Defense similarly overlooked the basic political problem that led to the doctrine in the first place, namely, the need to provide a credible conventional forward defense of West Germany. Keeping the Germans actively integrated into NATO depended upon assurances that a Soviet invasion could be resisted effectively without resorting to nuclear weapons. Indeed, the political cohesion of the NATO alliance itself rested on the contradiction between the credibility of U.S. assurances that it would defend Western Europe with nuclear weapons if necessary and the fears of alliance members that losing a battle for West Germany would make that necessity a reality.

Forward Defense in Eastern Europe

A cursory look at the current military situation in Eastern Europe along with Russia’s increasingly robust anti-access/area denial (A2/AD) capabilities (see map) should clearly illustrate the logic behind a doctrine of forward defense. U.S. and NATO troops based in Western Europe would have to run a gauntlet of well protected long-range fires systems just to get into battle in Ukraine or the Baltics. Attempting operational maneuver at the end of lengthy and exposed logistical supply lines would seem to be dauntingly challenging. The U.S. 2nd U.S. Cavalry ABCT Stryker Brigade Combat Team based in southwest Germany appears very much “lone and lonely.” It should also illustrate the difficulties in attacking the Russian A2/AD complex; an act, which Jennings, Fox, and Taliaferro remind, that would actively court a nuclear response.

In this light, Active Defense—or better—a MDO doctrine of forward defense oriented on “a fires-dominant force with robust capacity to defend in depth,” intended to “enable stated political aims to prevent adversary aggression rather than to invade their home territory,” does not really seem foolishly retrograde after all.

U.S. Army Doctrine and Future Warfare

Pre-war U.S. Army warfighting doctrine led to fielding the M10, M18 and M36 tank destroyers to counter enemy tanks. Their relatively ineffective performance against German panzers in Europe during World War II has been seen as the result of flawed thinking about tank warfare. [Wikimedia]

Two recently published articles on current U.S. Army doctrine development and the future of warfare deserve to be widely read:

“An Army Caught in the Middle Between Luddites, Luminaries, and the Occasional Looney,”

The first, by RAND’s David Johnson, is titled “An Army Caught in the Middle Between Luddites, Luminaries, and the Occasional Looney,” published by War on the Rocks.

Johnson begins with an interesting argument:

Contrary to what it says, the Army has always been a concepts-based, rather than a doctrine-based, institution. Concepts about future war generate the requirements for capabilities to realize them… Unfortunately, the Army’s doctrinal solutions evolve in war only after the failure of its concepts in its first battles, which the Army has historically lost since the Revolutionary War.

The reason the Army fails in its first battles is because its concepts are initially — until tested in combat — a statement of how the Army “wants to fight” and rarely an analytical assessment of how it “will have to fight.”

Starting with the Army’s failure to develop its own version of “blitzkrieg” after World War I, Johnson identified conservative organizational politics, misreading technological advances, and a stubborn refusal to account for the capabilities of potential adversaries as common causes for the inferior battlefield weapons and warfighting methods that contributed to its impressive string of lost “first battles.”

Conversely, Johnson credited the Army’s novel 1980s AirLand Battle doctrine as the product of an honest assessment of potential enemy capabilities and the development of effective weapon systems that were “based on known, proven technologies that minimized the risk of major program failures.”

“The principal lesson in all of this” he concluded, “is that the U.S. military should have a clear problem that it is trying to solve to enable it to innovate, and is should realize that innovation is generally not invention.” There are “also important lessons from the U.S. Army’s renaissance in the 1970s, which also resulted in close cooperation between the Army and the Air Force to solve the shared problem of the defense of Western Europe against Soviet aggression that neither could solve independently.”

“The US Army is Wrong on Future War”

The other article, provocatively titled “The US Army is Wrong on Future War,” was published by West Point’s Modern War Institute. It was co-authored by Nathan Jennings, Amos Fox, and Adam Taliaferro, all graduates of the School of Advanced Military Studies, veterans of Iraq and Afghanistan, and currently serving U.S. Army officers.

They argue that

the US Army is mistakenly structuring for offensive clashes of mass and scale reminiscent of 1944 while competitors like Russia and China have adapted to twenty-first-century reality. This new paradigm—which favors fait accompli acquisitions, projection from sovereign sanctuary, and indirect proxy wars—combines incremental military actions with weaponized political, informational, and economic agendas under the protection of nuclear-fires complexes to advance territorial influence. The Army’s failure to conceptualize these features of the future battlefield is a dangerous mistake…

Instead, they assert that the current strategic and operational realities dictate a far different approach:

Failure to recognize the ascendancy of nuclear-based defense—with the consequent potential for only limited maneuver, as in the seventeenth century—incurs risk for expeditionary forces. Even as it idealizes Patton’s Third Army with ambiguous “multi-domain” cyber and space enhancements, the US Army’s fixation with massive counter-offensives to defeat unrealistic Russian and Chinese conquests of Europe and Asia misaligns priorities. Instead of preparing for past wars, the Army should embrace forward positional and proxy engagement within integrated political, economic, and informational strategies to seize and exploit initiative.

The factors they cite that necessitate the adoption of positional warfare include nuclear primacy; sanctuary of sovereignty; integrated fires complexes; limited fait accompli; indirect proxy wars; and political/economic warfare.

“Given these realities,” Jennings, Fox, and Taliaferro assert, “the US Army must adapt and evolve to dominate great-power confrontation in the nuclear age. As such, they recommend that the U.S. (1) adopt “an approach more reminiscent of the US Army’s Active Defense doctrine of the 1970s than the vaunted AirLand Battle concept of the 1980s,” (2) “dramatically recalibrate its approach to proxy warfare; and (3) compel “joint, interagency and multinational coordination in order to deliberately align economic, informational, and political agendas in support of military objectives.”

Future U.S. Army Doctrine: How It Wants to Fight or How It Has to Fight?

Readers will find much with which to agree or disagree in each article, but they both provide viewpoints that should supply plenty of food for thought. Taken together they take on a different context. The analysis put forth by Jenninigs, Fox, and Taliaferro can be read as fulfilling Johnson’s injunction to base doctrine on a sober assessment of the strategic and operational challenges presented by existing enemy capabilities, instead of as an aspirational concept for how the Army would prefer to fight a future war. Whether or not Jennings, et al, have accurately forecasted the future can be debated, but their critique should raise questions as to whether the Army is repeating past doctrinal development errors identified by Johnson.


Trevor N. Dupuy (1916-1995) and General William E. DePuy (1919-1992)

I first became acquainted with Trevor Dupuy and his work after seeing an advertisement for his book Numbers, Prediction & War in Simulation Publications, Inc.’s (SPI) Strategy & Tactics war gaming magazine way back in the late 1970s. Although Dupuy was already a prolific military historian, this book brought him to the attention of an audience outside of the insular world of the U.S. government military operations research and analysis community.

Ever since, however, Trevor Dupuy has been occasionally been confused with one of his contemporaries, U.S. Army General William E. DePuy. DePuy was notable in his own right, primarily as the first commander of the U.S. Army Training and Doctrine Command (TRADOC) from 1973 to 1977, and as one of the driving intellectual forces behind the effort to reorient the U.S. Army back to conventional warfare following the Vietnam War.

The two men had a great deal in common. They were born within three years of one another and both served in the U.S. Army during World War II. Both possessed an analytical bent and each made significant contributions to institutional and public debates about combat and warfare in the late 20th century. Given that they tilled the same topical fields at about the same time, it does not seem too odd that they were mistaken for each other.

Perhaps the most enduring link between the two men has been a shared name, though they spelled and pronounced it differently. The surname Dupuy is of medieval French origin and has been traced back to LePuy, France, in the province of Languedoc. It has several variant spellings, including DePuy and Dupuis. The traditional French pronunciation is “do-PWEE.” This is how Trevor Dupuy said his name.

However, following French immigration to North America beginning in the 17th century, the name evolved an anglicized spelling, DePuy (or sometimes Depew), and pronunciation, “deh-PEW.” This is the way General DePuy said it.

It is this pronunciation difference in conversation that has tipped me off personally to the occasional confusion in identities. Though rare these days, it still occurs. While this is a historical footnote, it still seems worth gently noting that Trevor Dupuy and William DePuy were two different people.