On “Restoring the Primacy of Army Mobilization Planning: Lessons from the Interwar Period (1919–41)”

In this episode, Tim Devine and Jon Gerson argue that the US Army must restore the primacy of mobilization planning to prepare for the growing likelihood of a protracted large-scale war involving the United States. While the Army’s transformation initiatives have emphasized important tactical matters, Devine and Gerson call attention to critical strategic vulnerabilities associated with mobilization—one of the Army’s enduring core functions. They offer insights, identify challenges, and offer recommendations for contemporary leaders and practitioners by analyzing the body of thought on mobilization planning during the interwar period (1919–41) and drawing connections to the present day.

Keywords: mobilization, strategic planning, large-scale war, readiness, Interwar Period

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 Stephanie Crider (Host)
Welcome to Decisive Point. The views and opinions expressed in this podcast are those of the guests and are not necessarily those of the Department of the Army, the US Army War College, or any other agency of the US government. Today we’re discussing national mobilization.
While the United States military pivoted to an era of great-power competition years ago, the strategic environment continues to evolve. Joining us remotely today is Lieutenant Colonel Tim Devine, an active-duty Army strategist, author of “Restoring the Primacy of Army Mobilization Planning: Lessons from the Interwar Years, 1919–41,” which was published in the Summer 2025 issue of Parameters. He has strategic planning experience on the Army Staff and in the Indo-Pacific and is currently an instructor at the Army’s Command and General Staff College.
Tim, welcome.

Tim Devine
Thanks, Stephanie. It’s a pleasure to be here.

Host
We’re also joined by Colonel John Gerson, a Title 10 National Guard officer and senior planner at the National Guard Bureau. He brings experience from several key assignments in the Joint Staff, the Army War Plans Division, the office of the Secretary of Defense (now Secretary of War), and the Guard Bureau.
John, thanks for joining us.

Jonathan Gerson
Thanks, Stephanie. Thanks for inviting me on. It’s always great to share the mic with Tim.

Host
Tim, your article is the foundation for our conversation today. In it, you argue the Army must restore the primacy of mobilization planning. To start, could you summarize why you believe looking back 100 years to the interwar period is so crucial for the challenges the Army faces right now?

Devine
Absolutely. And first, I’ll emphasize that I’m a practitioner. I’m not a professional historian, but I was struck just by how much of this history is relevant for our contemporary time. Right after World War I, it was really the last time that the Army had to build a mass mobilization model almost from scratch. And World War I mobilization was chaotic and, although it was ultimately successful, there was a long list of shortcomings that illuminated the need for systematic reform.
And, this experience had a profound effect on those who took part, particularly those in the Army who later held prominent roles throughout the interwar years—so, Chiefs of Staff like [General] John [J.] Pershing, General [Douglas] MacArthur, [General Malin] Craig and, of course, General George [C.] Marshall. And, each of them advanced proficiency in strategic planning in their own way.
Now, fast forward to today, and there’s a lot that we can apply from this period. And, even during my time in uniform, which is approaching the 20-year mark, I’ve lived through the Army’s shift from the two decades of counterinsurgency to renew the focus on large-scale combat—or LSCO, as we call it. And given this shift institutionally, it’s clear that the Army is wrestling with how to prepare its forces for the growing likelihood of these potentialities.
This impacts everything—how the Army organizes itself, how we train our forces, how we equip them, how we measure readiness, and how we view and anticipate the character of war changing. There’s a lot of credible sources out there that have expressed the fact that there is a growing chance for large-scale conflict involving the United States. And, I know that’s a sobering aspect of the conversation today, but that reality emplaces an important demand signal on the Army. And, that demand signal is not only to fight the nation’s wars—fight and win the nation’s wars, rather—but to generate the force needed to do so. And, of course, these two things go hand in hand, but today’s discussion will focus on the latter.
And, I want to stress, too, that the force I’m talking about—the war-winning force—in all likelihood, far exceeds what we have today. And I’m not just talking about the active component. This includes the reserve component, which consists of the Army National Guard and Army Reserve. So, in other words, there must be a plan for generating the right mix beyond the force in being, and that could be difficult to imagine. So, the interwar period offers us a blueprint, not for perfect solutions, but of the intellectual journey needed to prepare.

Host
You mentioned the Army developed a planning ecosystem to tackle this challenge. What did that look like?

Devine
Overall, it was a network of institutions and processes that was really meant to build intellectual capital. And, through this ecosystem, the Army learned to speak the language of national mobilization. And, to me, that’s really the biggest takeaway that I gained from studying this period. And, during my research, a colleague of mine recommended I read Henry [G.] Gole’s book titled The Road to Rainbow.
And, I’m sure that title is familiar to many of your listeners, but for those that are not familiar with this, Rainbow, of course, refers to the famous Rainbow Series plans. These replace the so-called Color Plans that were, as one Army historian put it, “little more than abstract academic exercises.” But, to get us to an integrated set of plans, Gole explores this ecosystem—the planning ecosystem—created by the Army, which consisted of four pillars.
First was professional military education. The second was practicums—think like war games and exercises and so forth. The third was studies, and the fourth was continuous planning. There’s really a lot I could go into about Gole’s work, but just given that we’re constrained on time here, I’ll focus my comments about the cumulative effect of it all—so, the formal education, follow-on assignments to the War Plans Division, [of] which Colonel Gerson and I are proud alumni, constantly writing and rewriting these plans.
All of that proved invaluable. And, while the plans themselves were riddled with flaws, especially the early plans during the 1920s, it was the process, really, that revealed not only the problems’ immense complexities but also the extraordinary scope. So consequently, over time, the plans got better and, eventually, they linked force-generation requirements to operations envisioned by the regional war plans. They drew connections between the two chief commodities, which I like that term. It’s one I borrowed from the readings that I found during my study—the two chief commodities, the mobilization, manpower, and materiel. And, the assumptions became more realistic. The calculations got better. So, when war finally came, this intellectual capital gain from these integrated planning frameworks was arguably the most valuable strategic asset that the Army had.

Host
Your article highlights significant disconnects during that period between manpower and materiel plans and between defensive assumptions and offensive war plans. Do you see similar gaps today?

Devine
I do, and I touched on this briefly, so I’m glad you’re giving me a chance to unpack the idea further. For me, during my study of the interwar years, it illuminated how important those connections are. And, I’m talking about the connections between the interrelated parts of an immensely complex system that we call national mobilization. So obviously, many of these parts, like supply chains, for instance, transcend the Army, but they’re all related.
[The] first point I’d like to make is [that we should] consider these two basic commodities that I mentioned earlier, manpower and materiel. And, the World War I mobilization experience was really a failure to synchronize the two. I mentioned it was a success in the long run, but this is one of the big points that came out of it. And I really like the quote from Arthur Herman, who’s the author of Freedom’s Forge, to illustrate this point.
And that’s another title many of your readers are probably familiar with. So, Herman writes “[Of] the 10,000 75mm artillery pieces the War Department ordered, only 143 ever reached the front—and not one American-made tank.”
So, interestingly, the disconnect between manpower and materiel planning remained prevalent throughout the 1920s and into the 1930s. And, it’s easy to see the flaw here, but I assure you that planning stovepipes are still alive and well. The second point [is] throughout most of the interwar period, there was a huge disconnect between the concepts guiding the mobilization plans and those for the regional war plans. So, the mobilization plans were based on defensive concepts like hemispheric defense, whereas the regional war plans like War Plan Orange were offensive.
So, in other words, if the Army had to fight War Plan Orange, there was not a corresponding mobilization plan to generate the force needed to do so. And those that know their history here, the Army of the interwar years was a Spartan-sized, poorly equipped force that really couldn’t handle any contingency scenario, let alone anything for hemispheric defense.
Now, if we apply these insights to the contemporary setting, national strategy today prioritizes both homeland defense and deterring China, plus a number of other demands. And, this creates a really complex demand signal for the Army. And, fortunately, we have these detailed, interconnected war plans, but what we lack is a modern integrated mobilization plan to connect and resource them.
So notably, the department’s last master mobilization plan was inked during the [Ronald] Reagan administration, which was nearly 40 years ago. So, in other words, we’re missing the comprehensive plan that details how to mobilize manpower, industry—heck, our society and our economy—for a large-scale, multiyear war.

Host
John, as someone who works these issues daily at the National Guard Bureau, how do Tim’s points about these disconnects—and this new factor of a contested mobilization—resonate with you?

Gerson
So, Tim’s absolutely right, and his points resonate deeply about the things we grapple with daily at the Bureau, the disconnects and gaps that the War Department identified after both World War I and World War II are presenting vital lessons today. In essence, the US military’s manpower and materiel requirements for both offensive and defensive plans have got to be synchronized, and planners have got to consider them both happening at the same time.
That problem has become now even more acute because the homeland is going to be contested in ways that were not possible a century ago. So, the core assumption that’s underpinned our planning for several decades, as Tim mentioned, a sterile, uncontested mobilization from a secure homeland, is gone. We’ve now got a plan for a scenario in which the homeland is a target from the first hour of conflict.
This means preparing for kinetic strikes on our strategic seaports, cyberattacks meant to paralyze our infrastructure and logistics systems, and sophisticated misinformation campaigns designed to erode the public will. This reality fundamentally changes the classic challenges of scale and speed. So, it’s no longer just about moving forces efficiently or predictably, as most of us today in the Army in uniform have grown up thinking about.
It’s about mobilizing your forces, including the Reserves, while under active attack, kinetic and non-kinetic. As an operational force from day one, the Guard faces pretty immense challenges of simultaneously defending the homeland and projecting power from it as part of the Joint Force. And finally, unlike the interwar planners who could design force expansion models based on a large pool of draftees, we’re constrained by the realities of a finite, all-volunteer force.
Of course, the draft still exists—in law. Selective Service still exist—in law—but the nation does not think about those things in the way they used to. Neither does the Army or the War Department. This presents force-generation challenges we haven’t had to confront since the early 1970s during Vietnam, when the draft still existed in a fairly limited form by global conflict standards. Trying to synchronize equipment fielding, collective training, and modernization across 54 states and territories, all at the speed of modern war and under constant enemy pressure is a condition with which planners contend regularly at the National Guard Bureau. That’s something we’re struggling with and thinking about deeply. The scale and complexity are unlike anything we’ve faced because, in addition to the speed and scale requirements, modern technology is now complicating that challenge even more.

Host
You mentioned the Guard’s role in securing infrastructure. Does this also extend into the broader realm of what we used to call civil defense?

Gerson
It does, and I think this becomes a fascinating nexus for the National Guard and a real societal-level challenge. In a modern, contested homeland scenario, the historic line between military defense and civil defense breaks down. It ceases to matter. So, the National Guard is a dual-hatted force with that mission, serving both state governors and the federal government.
So, it’s a natural bridge between the Department of War, focused on war fighting and the domestic needs of the nation. When a pure adversary targets the US homeland, the Guard transcends its modern combat reserve role. Again, as people regularly think about the National Guard and the GWOT (global war on terrorism) period over the last 25 years, it becomes a backbone of a comprehensive civil defense effort.
In some cases, the Guard’s really going back to its original roots. Long before the modern Department [of War] and back to its roots as a militia. So today, this means the Guard units would not just protect critical infrastructure from cyberattacks while mobilizing and deploying overseas. They would surge to support civilian first responders, providing engineering, logistics, medical capabilities to potentially manage even mass casualties.
They’d be asked by both the federal and state government to ensure continuity of government, and all its complexities, by securing leaders’ communication nodes, all while helping communities recover from strikes and maintaining public order in support of law enforcement. This is not a secondary mission or a secondary consideration in a major conflict. It’s a strategic imperative, and it ensures the US military can project combat power and sustain it.
A homeland that is able to do that ensures the war fight. A resilient homefront is a critical national objective, again, something we spend a lot of time thinking about in the National Guard Bureau—and across the National Guard—as a natural bridge to America’s communities and a necessity for preparedness.
So, any viable modern mobilization plan must include a robust civil defense component because no amount of military is going to unilaterally solve these challenges. It necessarily is whole-of-nation.

Host
Let’s talk about the materiel side. The interwar planners struggled to get industry on board. We don’t have that today. We have a permanent military industrial complex and new technologies. Does that make the problem easier or harder?

Devine
Yeah. Stephanie, I think that’s a great question because it cuts both ways. On one hand, having an established industrial base is a great advantage. However, that base is optimized for peacetime efficiency and just-in-time delivery, and those conditions make it incredibly fragile. And we’ve seen, just with support to Ukraine, how quickly stockpiles of key munitions like 155 [mm] artillery shells can be depleted, not to mention expensive complex manufacturing processes for high-end systems like the F-35 or smart munitions like PrSM (precision strike missiles).
Clearly, ramping up production is going to take years, not months. And for its part, the military owes a clear demand signal for industry, not just for its steady-state requirements, but also for the war-fighting requirements—and this includes plans for surge capacity. So, this was an acute problem, actually, during the US, or when the United States was ramping up its production on the eve of World War II.
For example, Bill Knudsen, who led the Office of Production Management, he sharply criticized the military for consistently failing to articulate the types and quantities of materials the military needed. And, this was despite the fact military leaders were constantly demanding industry to do more. So, you can’t convert a car factory overnight into an assembly plant for tanks like we did in World War II, cause that’s another consideration we have to think about is that these skills, materials, digital components that we have nowadays are just far too specialized.
And for instance, the Navy’s shipbuilding goals alone present industry with a Herculean challenge. Then you add in fifth- and sixth-generation aircraft, modernizing the nuclear arsenal, producing all these sophisticated tools for space and cyber forces. And, then you put the Army’s requirements on top of that. I mean, the Army’s competing in many cases for the same resources, raw materials, contracts, industrial workforce, you name it [as businesses]. So, while we have this warm industrial base, its ability to scale rapidly is unknown. And, quite frankly, it’s a source of strategic vulnerability.
And, granted there’s a lot of positive momentum underway to reform the acquisition system, but planning for the expansion—it’s really identifying bottlenecks, securing rare earth minerals, building redundant capacity, fielding platforms that are scalable—all of that has to happen now, not just when a crisis hits.

Host
I’d like to talk a little bit more about scalability. John, how do emerging technologies like AI, drones, and 3D printing fit into this complex industrial picture?

Gerson
So, this is a fascinating problem and a critical point. It gets to the heart of the paradox with emerging technologies. On the one hand, technologies like AI, autonomous drones or semi-autonomous drones, and additive manufacturing are potential game changers for scalability. We’re already seeing it all over the Department of War, across the services. Instead of waiting weeks for spare parts from a depot overseas, we could, for example, use 3D printing to create it on demand at the point of need, drastically reducing the reliance on a fragile long-distance supply chain system.
Drones integrated with AI could automate countless tasks, from perimeter security and surveillance to battlefield logistics, freeing up manpower and increasing efficiency. [These technologies are] just things people look at regularly. It’s a powerful way to do more with less. However, this technology strength creates a new, more sophisticated set of vulnerabilities we haven’t really thought enough about, in my opinion. These systems are not self-sufficient.
Additive manufacturing requires specialized polymers, metal powders, precursors, et cetera. Drones and AI systems are utterly dependent on a global supply chain system for their core components. Microchips, advanced sensors, rare earth minerals—these are all things that the United States buys from the world in order to make these advanced weapons and systems that we have.
An adversary does not need to sink a ship carrying tanks or planes if they can halt the flow of microchips from Taiwan or rare earths from China. Our advanced technological capability could become an Achilles heel if we fail to secure the foundational inputs. We risk building a highly advanced but hollow house of cards without ensuring key industry capabilities and materiel through the defense industrial base, organic and nonorganic, and the broad American economy support. It’s clearly a risk that Sec War and others have identified, and they’re working to fix.

Devine
Yeah, actually, I’d like to jump in here, too, because technology lets us be more creative about what production means. This old factory model that we’ve done isn’t the only way. And we’re already thinking about how to distribute production beyond this old factory model. Just consider all of the different exercises that the Army and other services are doing [like] 3D printing in forward and austere locations—and on deployments, too.
I mean, there’s a lot that is being demonstrated as to what’s possible. I just think the next challenge is how to scale it. So, scaling for, say, a division-sized operation, enough drones in a 24-hour period, that’s really the next logical step. And, if we look back to the last century of what the US so-called “arsenal of democracy” was able to do, there’s a lot we can imagine of how much, in terms of quantity, we can produce in distributed ways.
So, it also comes with new requirements, new risks, but we should be thinking about ways like this as a paradigm shift from this centralized production system to more of a networked foundry that produces materiel on demand and where needed.

Host
This is such a good segue to my next question. Tim, you’ve written about the role of technology in military education. How can technology—and I’m really talking about artificial intelligence here—shape the planning process?

Devine
I didn’t think much about how to apply futuristic technologies like artificial intelligence because I was just so fascinated by studying our past experience. But, the more I’m exposed to it in my current role as an instructor and just gaining more interest in it because of the implications that it could have, [I realize] there’s a lot that you can use for these technologies for the problem that we’re talking about.
And really, that core problem for national mobilization is one that’s more-or-less cognitive overload just because of the staggering amount of variables that are involved. And here, AI can be a game changer. So, in the planning ecosystem, it shouldn’t be an easy button, but it could be a tool that we could use to ask better, more complex questions.
And I think, more importantly, it could allow us to move faster. So, we may not have the luxury of waiting two decades to build up our intellectual capital like we did last century, but we can certainly set conditions for a rapid transition in faster ways than we did before. And this is then using AI to, like, power models, war-game mobilization scenarios at a scale, identify gaps, helping us form solutions long before a crisis hits.
And, you know, I mentioned the fact [that] I’m an instructor in professional military education. We can give officers different scenarios or simulations that can provide a real-time interface instead of just studying, say, a static case. In short, there’s a lot that human-AI teaming can offer, and it’s a powerful combination that planners of [the] last century lacked. And, we can get there a lot faster if we use these tools wisely.

Host
So, we have these complex challenges, and we have new tools. How does a modern mobilization plan properly nest within a national theory of victory in the actual war plans that the military would execute?

Devine
Yeah, I’d say this is the most crucial link because the mobilization plan is the engine that fuels wartime preparation. And there’s this old saying attributed to, General [Dwight D.] Eisenhower. And, we heard it all the time when we worked in the War Plans Division, which, of course, General Eisenhower led the War Plans Division for a brief period before World War II.
But, General Eisenhower said, “Plans are nothing; planning is everything.” And, it goes back to my point I made earlier about the process. So, the process instills the intellectual capital, and our theory of victory dictates the type of force we need and the timeline that we need to generate it on. And, it makes this critical feedback loop (because it’s a living plan) back to the war plans. And of course, our plans have to account for winning the first battle because the risks of a long war in today’s age against a nuclear-armed rival could be potentially catastrophic. However, we can’t afford a force designed only to win that first battle because that force that wins the opening round has to contain the seeds of a much-larger force needed for, potentially, a longer and even more violent campaign.
And historically, this is where the Army has failed to win. America’s First Battles, The American Way of War, those are great books that go into these issues. And our so-called American way of war has us take our licks, regroup, and then deliver that overwhelming force. “Build the iron mountain”—as many of us are familiar with that term.
But, recalling the importance of making connections, this means planning for a cadre of units to train conscript forces. So, you know, we talked about the Selective Service System briefly going beyond the all-volunteer force, considering pretrained manpower pools, a warm industrial base ready to surge requirements. It also connects to the Army’s historic responsibility to strengthen ties between the military and the society it serves—so not just the Army, but the military writ large.
And, just to briefly go beyond what I mentioned about the all-volunteer force, it’s been relatively successful for half a century. But the AVF (all-volunteer force) has its limits. And the Army—and the nation, for that matter—requires the capacity to rapidly transition from competition to LSCO environments, not just for a pitched battle but for a long war.

Host
From a practical standpoint, John, what does that feedback loop look like? How does the reality of force generation in the Guard and Reserve inform those high-level strategic plans?

Gerson
Sure. I think Tim really hits the nail on the head with this one because the type of force a combatant commander needs requires a mobilization plan that considers a long war for both homeland defense and war fighting abroad. If you simply design a war plan for a short, sharp war that seems to be bloodless and convenient and achieves your objectives, you’re unlikely to succeed in the long run in the kind of scenario we’re describing.
So, that practical feedback loop between the National Guard and Reserve—and even at the National Security Council, through the Chairman of the Joint Chiefs and his staff—is centered on providing ground truth to prevent the creation of fantasy plans. This process has got to involve an honest conversation about what’s truly achievable. This goes on all the time inside of the Department, but it’s important to highlight, when a planner, for instance, requests an Infantry brigade or logistics and sustainment from the Reserves or Guard on an overly optimistic time frame, it is incumbent upon the Guard to provide real-world data on readiness rates, maintenance backlogs, and the extensive training requirements, and then to manage the expectations and mitigate risk. This means demonstrating a realistic timeline that can be measured in months, not days, particularly when concurrent civil defense missions are considered—or homeland defense missions in today’s parlance.
And so, this reality ultimately forces a really crucial decision point for leadership, civilian and military. [If] they end up having to choose whether to invest significantly in more readiness to meet rapid timelines, that’s a choice. That’s a type of force you build. Or [you] formally assume a higher degree of strategic risk that that initial rapid timeline will work out for you.
And if not, revise the military objectives on the advice provided by your military planners. Right? By presenting the unvarnished facts, the Guard and Reserve can act as [an] essential check on strategic planning, assuring that the final war plans are anchored in what’s really achievable. How fast it can be done and at what cost? And, these three things matter deeply in the national mobilization Tim’s describing. Ultimately, this prevents developing contingency plans that would collapse on contact with reality.

Host
This has been incredibly rich and, quite honestly, sobering. So, as we wind this down, as we approach the end of our time, I’d like to hear any concluding thoughts that you each might have. John, why don’t you start us off?

Gerson
Achieving a successful national mobilization—or developing the plan for it—is fundamentally a team sport. It is a whole-of-nation approach. It’s only a viable path to succeed. This effort’s got to demand collaboration, not just within the military, but across a broad spectrum of partners, including Congress, private industry, technology innovators, and even international allies. The National Guard is—of course, I’m speaking about it as a living embodiment of the citizen soldier legacy—we’re central to that solution, bridging the gap between military and American society, but not alone, as part of a larger team. So, this means considering a war in which we do not win the initial fight. That underpins the idea of a large national mobilization. And, that should drive people across the country, in government and outside of government, to consider the types of challenges with which we’ll be faced.
Ultimately, I hope that this conversation spurs concrete action. I think during a time of peace is always easier to consider these solutions than in the middle of a crisis or in a war itself, as Tim described.

Host
Thanks, John.
Tim, last word to you.

Devine
Optimistically, we are making progress. There’s a lot of positive efforts that are underway, but I think our discussion highlights the urgent need for a national-level strategic planning framework because this problem is too big for any department, any branch of government, for that matter, and the Army has a unique role here and, quite frankly, a unique responsibility given its Title 10 responsibilities that have been longstanding.
So, the Army can jumpstart this effort. And, you know, the Army obviously has a lot at stake here, considering we’re the largest service [and] would require a large number of forces in a wartime scenario. But these Title 10 responsibilities that I’m talking about, like mobilizing, deploying, sustaining at scale, have largely been overlooked since the end of the Cold War. And so, there’s a responsibility the Army has to prepare the society that it serves for these wartime things that we’re talking about.
Of course, these are unpleasant conversations, but they’re necessary. And, threading the ties more strongly between society and the Army doesn’t always have to be about doom and gloom. There’s thoughtful ways that we can improve these ties and, thus, our general preparedness. And I’d say that the first step the Army can make is restoring the primacy of its strategic planning efforts as a catalyst, potentially, for putting us on the right path.
So, thanks, Stephanie. I appreciate that.

Host
It’s a powerful and urgent message from you both today. Lieutenant Colonel Tim Devine and Colonel John Gerson, thank you for sharing your expertise and your insights with us.
Listeners, you can read the genesis article at press.armywarcollege.edu/parameters. Look for volume 55, issue 2. For more Army War College podcasts, check out Conversations on Strategy, SSI Live, CLSC Dialogues, and A Better Peace.