How the U.S. Military Learned to Learn in World War I: Lessons from the American Expeditionary Forces


Is there an “American way of war?” To answer this question, one would do well to start with the American Expeditionary Forces (AEF) in World War I, often rightly said to be America’s first modern war. The AEF exhibited both good and bad traits. To begin with the bad: One finds arrogance and the conviction of superiority vis-à-vis America’s allies and enemies, along with the assumption that they had nothing to teach U.S. forces. The good: Notwithstanding the initial arrogance and conservative institutional culture, some commanders and their men displayed an ability and willingness to learn, especially at the operational and tactical levels. Most importantly, they recognized that in fact America’s allies had a great deal to teach the U.S. military. Rather than let their self-confidence close their minds, they saved it for assertiveness on the battlefield.

Central to appreciating the Great War as fought by the AEF are two facts. First, the violence was extreme. Fifty-three thousand Americans were killed within a relatively short span of time. The first fell in November 1917, but Americans were not heavily involved in the fighting until the late spring of 1918 and were never more than junior parties compared to the British and French armies. Even then, most of the killing took place in the period that began in mid-July with the Second Battle of the Marne. In fact, almost half (26,000), lost their lives in the final Meuse-Argonne Offensive, which began on Sept. 26, 1918 and still ranks as the largest and deadliest battle in American history.

Second, the U.S. military had no idea what it was doing. It had no real experience with modern warfare and didn’t learn much about it from the experience of the belligerents who had entered the war earlier. The United States therefore joined the battle largely with the same innocence the others had possessed in August 1914. Worse, it refused to learn when given the opportunity. As Mark Ethan Grotelueschen documents in his terrific study of The AEF Way of War, American officers visiting the front largely saw what they wanted to see, which was validation of their institutional assumptions about how war should be fought and their conviction that the U.S. military was superior to those of the Europeans. General John J. Pershing and many of his lieutenants clung to romantic 19th century notions about warfare. Among these was the belief in the sufficiency of rifle-armed infantry and the conviction that the American rifleman in particular — through his skill, certainly, but above all thanks to his great character and spirit — would do what the British and French had failed to do: break the Hun. The implication was that the allies were lacking in character and were almost unmanly in their taste for trenches and the various accoutrements associated with trench warfare, chief among them machine guns and massed artillery, but also grenades and mortars.

The story of the AEF, then, is about how rapidly and how completely some of its commanders and, of course, thousands of soldiers and marines (it was a joint force), learned — despite their own initial ignorance and the larger Army’s intellectual handicaps. On his own, Pershing might never have understood the war he helped to win. His contributions arguably lay in his political and organizational skills, his ability to create and lead a vast military built essentially from scratch. However, as Grotelueschen has ably documented, a number of his division commanders and lower-ranking commanders caught on. They, with help from British and French advisers, and in some cases in defiance of their superiors and even their orders, learned in weeks and months what the allies and the Germans had figured out over the course of three years of horror. Today, the AEF serves as a cautionary tale about the risks of remaining beholden to old ideas, and an optimistic reminder of the benefits of being willing to learn from allies and adapt, even in the face of outmoded institutional thinking.

Baptism by Fire: Learning Modern Warfare

What was “it” that the Americans had to learn? The problem in World War I, the reason the two sides found themselves locked in a murderous stalemate, was firepower. Modern rifles, machine guns, and above all artillery rendered suicidal the kind of open field maneuvers British, French, and German commanders dreamed of in 1914, and that Pershing still did in 1918. One simply could not survive above ground. Even if one broke through the enemy’s lines, it was still nearly impossible to exploit breaches once the forward troops were out of range of their side’s artillery. At any rate those advancing troopslargely lacked the ability to communicate with those guns that were in range. Thus defenders could mass their own fires, smash to pieces advancing forces, and push them back nearly to the point of departure.

Armies on the Western Front had to learn to fight differently from what their doctrines and field manuals advocated at the beginning of the war. They had to learn to eschew closely formed columns or waves and use terrain features for cover. They also had to learn true combined arms combat, which meant figuring out how to remain in contact and work closely with artillery while integrating organic firepower — mortars, hand grenades, and rifle grenades — into smaller units. The armies had to incorporate and bring forward far more machine guns than any of them originally had on their tables of organization. Automatic weapons, the importance of which armies underestimated before 1914 (or 1918, in the Americans’ case), suddenly became critical. Up until that point, it seems institutional culture and the cult of the rifle and the bayonet had blocked the full adoption of these weapons. The armies also had to learn to give up on the fantasy of the big breakthrough in favor of incremental advances carefully coordinated with artillery.

The British, French, and Germans all figured this out, learning and evolving, however slowly. Military theorist and historian Paddy Griffith has shown how, by 1917 if not earlier, the British Expeditionary Force had largely figured “it” out and was already fighting a very different kind of war, sometimes with the support of superior officers, sometimes despite their opposition. The force learned to attack using more fluid lines, dispersed units, and far greater quantities of firepower. It learned to mass barrages and then have its men hug the rolling curtain of fire. It learned to flow around strong points and have others mop them up. Bruce Gudmundsson and Timothy Lupfer have documented how the Germans, for their part, developed similar methods which they referred to as “infiltration,” “assault,” or Sturm tactics; the troops schooled in these methods were Sturmtruppen (which is how the first true assault rifle, the German Sg44, earned the moniker Sturmgewehr, or “assault rifle” — the weapon dates to the Second World War but arguably has its conceptual roots in the tactical thinking of the First). The French did the same, as Michel Goya ably describes in his new history of 1918. According to Goya, France fielded in that year a profoundly different army than it had in 1914, one that truly combined arms at the lowest echelons and had mastered challenges such as keeping infantry in communication with artillery and using aircraft to keep both informed while also providing close air support. Ultimately, the great lesson for the French could be summed up by General Philippe Petain’s assertion that “Artillery conquers; infantry occupies.” The rifleman with his big battle rifle and bayonet mattered little. Artillery and other fires, rather than being auxiliaries to the infantry, became the focus. If anything, it was infantry that supported them.

Given all this, it was no accident that the German offensive in the spring of 1918 achieved as much as it did and restored an unprecedented degree of movement; it was no accident either that the counter-offensive launched by the allies, Americans among them, did so well. As for why it took so long for the three great European armies to achieve this level of proficiency, Griffith offers a compelling explanation: The rate of attrition in the armies was so great as to inhibit the accumulation of institutional memory. There were simply not enough survivors in veteran units to pass on hard-won knowledge, and it took time for units to acquire the skills needed to perform the tasks they increasingly understood to be necessary.

A Slow Learner Enters the War

The Americans who began pouring into France at the end of 1917 were largely unaware of this new form of warfare, due in part to senior commanders’ unwillingness to learn from the belligerents as well as an inexplicable sense of exceptionalism and an imagined innate superiority of the young country over the old. Once in France, most American units were taken under the wing of the French army (the rest by the British), which tried to teach what it could. Sometimes these lessons ran contrary to the preferences of American commanders who, according to Grotelueschen as well as Kenneth Hamburger, feared the foreign advisers might pollute the men with their ideas about trench warfare. Both studies describe a tug of war in the training camps between the French, who wanted to teach trench warfare, and AEF headquarters, which clung to other ideas.

Once in battle in the spring and summer of 1918 American officers defaulted to the old-school, infantry-centric approach favored by Pershing. This amounted to lines of infantrymen with fixed bayonets advancing on enemy positions with little in the way of artillery preparation prior to the attack, light fire support, and inadequate communications with supporting artillery. On the defensive, men were expected largely to rely on guts and the firepower of their Springfield rifles. The hope was for a breakthrough and a rapid resumption of maneuver warfare rather than static fighting.

Remarkably, though, AEF units learned fast, sometimes within days and weeks. Writing of Belleau Wood and subsequent fighting at Vaux, Grotelueschen comments that “what began in June and July with a futile bloodbath of inexperienced Marines in the wheat fields” next to Belleau Wood “ended with well-orchestrated combined arms attacks that annihilated enemy garrisons with relatively little cost in American life.” Americans learned to disperse and hug the terrain. Perhaps more importantly, they learned not to operate without massive fire support, close coordination with artillery, and ample supplies of mortars, rifle grenades, Chauchat light machine guns, and field guns. Thanks to French trainers (and French-supplied guns), American gunners mastered the art of carefully planned barrages, rolling barrages, and box barrages; commanders, for their part, learned to value these things and make them central to their plans and operations. Finally, they learned to keep the gunners connected to everyone else, so that they knew where to aim and where not to. When Americans did not have enough of their own supporting forces, they learned to borrow them from the British and French, which also meant learning to interoperate with them. The Americans also discovered the power of aircraft — again borrowed above all from the French, for the U.S. military as of late 1917 effectively had few aircraft and even fewer ideas what to do with them. They also learned to work with tanks — British and French tanks, often with British and French crews. Patton rolled to battle in a French tank. This is not to say that by November 1918 the entire AEF had mastered modern warfare. Morever, the skill level probably varied significantly from one division to another as fresh new divisions joined the fight alongside veterans. But they were fighting better, and differently.

As Grotelueschen and others have shown, in some divisions, it was the commanders themselves who adapted, while in others the commanders preferred to fight by the book, while their subordinates used what wiggle room they had to adapt and fight differently. Often the difference had to do with the quantity and kind of fire support allocated for attacks: The fast learners wanted more guns on hand to fire more rounds, and for longer periods of time; they wanted rolling barrages, and they wanted the guns to work closely with infantry. For example, General John Lejeune, of the United States Marine Corps, when he commanded the 2nd Division, became an artillery enthusiast and interpreted his orders liberally to have more fire support at his disposal and use it extensively. The AEF inspector general at one point criticized him officially for not fighting according to doctrine. Ultimately, instead of showing the British and French how it was done, as Pershing had expected, the AEF, with commanders like Lejeune leading, learned to fight like the British and French.

That character and spirit Pershing valued so much did help, however. The British and French really were tired. What they needed, and what Pershing provided, was a vast army of eager optimists. The innocent Americans proved ferocious from the moment they first saw combat, even if they fought rashly, like the marines who first assaulted Belleau Wood. (For a rich discussion of how the AEF fared in combat particularly in the first half of 1918, see Terrence Finnegan’s ‘A Delicate Affair’ on the Western Front: America Learns to Fight a Modern War in the Woëvre Trenches.) In July at the Marne, the Americans’ grit may in fact have saved the day, for they held their part of the line against all odds and contrary even to good sense. But it was not until members of the AEF learned to combine their bravura with British and French savoir faire that the American military became formidable.


For today, the lessons of the AEF’s experience are several. First is the danger of being beholden to accepted ideas and being unwilling to learn from what should have been evident truths. Technology had changed, quickly, but ideas had lagged behind. This delay cost the lives of thousands of many young British, French, Germans, and, arguably, Americans. The second is the danger of being unwilling to learn from one’s allies. The American military was convinced of its superiority even though it had no reason to think it knew any better than the British or French. But the more open the Americans were to their allies’ wisdom, the better they fought and the less they suffered. This brings us to the third lesson, which is the importance of being willing and able to learn. AEF units learned, but largely despite their top commanders. One can only imagine how much better Americans would have fared had their leaders encouraged learning and adaptation rather than discouraging it, and had each new division, upon entering the line in the summer and fall of 1918, not had to climb so steep a learning curve. As good as the AEF had become by November, it still had a lot to learn, and the casualty rates need not have been as high as they were.

In more recent conflicts, one can point to specific instances where U.S. forces might have done better had they been less arrogant or more willing to learn from others. David E. Johnson, my colleague at the RAND Corporation, has argued that many American lives might have been saved had the U.S. Army bothered to learn German armored doctrine before it invaded Normandy. In Vietnam, Americans made efforts to learn from the French experience in Algeria and Indochina, although one can debate how well they applied those lessons or if they learned the right ones. In any event, they failed like the French.

Today, it is safe to say that the U.S. military generally believes it has little to learn from its allies. Although it is serious about cultivating interoperability, the focus tends to be on working together, not necessarily on learning from the others. The “American way” is usually taken to be the gold standard, and America’s partners are expected to accommodate themselves to it. One French liaison officer stationed in the United States recently complained to me of what he said was the penchant of American commanders for telling their audience that the U.S. military commanders were the best. No doubt this is intended to inspire pride and esprit de corps. But even if it were true, the officer suggested, might it not be more prudent to assume otherwise and try to learn?


Michael Shurkin is a senior political scientist at the nonprofit, nonpartisan RAND Corporation.

Image: Wikimedia Commons