Setting a New Course: After World War I — How the Marines Found a New Mission with Amphibious Warfare

Marines Heading for Action: World War I

By Chris K. Hemler

The Marine Corps had emerged from the First World War with newfound credibility, combat experience, and, most importantly, public support. Throughout their service in General John J. Pershing’s American Expeditionary Forces—and most notably at Belleau Wood—the Marines displayed remarkable courage, grit, and resiliency. Enjoying more autonomy and higher-quality recruits because of their Service’s relatively small size, the Marines used their wartime exploits to nurture their identity as an elite, specialized force. A dash of embellishment on top—aided by the complicity of the American press corps—solidified the Marines’ image all the more. Even before the belligerent nations made their peace at Versailles, France, in 1919, the Marine Corps had bolstered its reputation as a distinct and unparalleled American fighting force.  Yet, even in light of a reinforced image, Marines and outsiders alike continued to disagree about the Corps’ proper role in the American military apparatus. Should the Corps continue a trend of expeditionary service, act as a colonial police force, or reassert its naval roots and purpose?  Though the Service had strengthened its standing, the First World War further compromised the existential purpose of the Marine Corps.

In the shadow of the First World War, then, the Marines returned much of their focus to their prewar function as an advanced base force of the U.S. Navy. Under this vision, which found both its roots and its strength in the ideas of the indomitable naval theorist Alfred Thayer Mahan, the Marines were to act as a maritime force capable of securing and defending overseas bases that would, in turn, sustain American warships anywhere in the world. By seizing an expanding web of coaling stations for the U.S. fleet, the Marine Corps would play a fundamental role in any future naval conflict.

Despite an obvious amphibious connection with the Marines’ future operations in World War II, this early concept of advanced base operations differed in one basic element: it was a reactive, defensive force rather than a robust team built for offensive landing operations. Based on the early model, the Marines were to seize vacant territory and fortify it for battle. At most, they anticipated nominal resistance. More likely, the Marines expected to land ashore and simply claim the bases as their own. As two notable Marine historians revealed, “in practice all of the training concentrated on the defense. . . . The advance-base force was in actuality little more than an embryo coastal artillery unit.”  

John Lejeune

Two Marines in particular deserve credit for gradually shifting the Corps’ attention from the defense of unoccupied shores to the rapid, offensive seizure of strengthened enemy posts. The first, Lieutenant General John A. Lejeune, became Marine Commandant in 1920 and set the Service on a progressive but patient path toward aggressive amphibious operations. Unsettled by growing Japanese aggression in the Pacific and alarmed by the significant territorial concessions made to the Japanese at Versailles, Lejeune connected American security in the Pacific with the United States’ ability to launch offensive landing operations across the region. Pursuing his vision for a modern Marine Corps, Lejeune slowly refined and buttressed the Corps’ purpose in light of contemporary security concerns.

Lejeune was hardly the first to acknowledge the growing rift in the Pacific. Indeed, by the early 1920s, the Navy Department identified Japan as its most likely future enemy and began deliberate preparations for the looming contest. The Americans’ resultant plan— famously labeled War Plan Orange—went through a series of revisions in the succeeding decades, each of which centered on defending the Philippines and leading a prolonged naval campaign to capture Japanese bases across the Pacific. Here, Lejeune’s shift toward offensive amphibious operations neatly paralleled (indeed, reflected) the Navy’s intention to turn back Japanese expansion. War with Japan would compel a succession of amphibious assaults across the Central and Western Pacific. Lejeune, and Marine leaders who followed, were determined to position the Marine Corps for that exact task. Of course, shifting the Marines’ focus to offensive landing operations not only helped solve the operational problems of a future Pacific War, it also delivered an existential purpose for the post–World War I Corps.

To study the growing problem in the Pacific with more focus, Lejeune appointed a brilliant young staff officer by the name of Lieutenant Colonel Earl H. Ellis. Though Ellis was known as a heavy drinker with a fiery temper, he also carried an equally established reputation as one of the Corps’ most talented strategic thinkers. Even for the disciplined and professional Lejeune, Ellis’s aptitude as a Marine officer far outweighed his dangerous penchant for stiff drink. As commanding general of the 2d Marine Division during the First World War, a subordinate once alerted Lejeune that Ellis appeared “indisposed” because of his usual habits and might therefore be unsuited for his battlefield duties as adjutant. In reply, Lejeune snapped that “Ellis drunk is better than anyone else around here sober.”

Earl Ellis in France, 1919

Having established a personal rapport with Lejeune, Ellis emerged from World War I ready to tackle the general’s next great task: that of confronting the Japanese in the Pacific. Alongside the Navy Department’s broader development of War Plan Orange, Ellis quickly acknowledged the disturbing but unavoidable work that awaited the Corps. To win a contest in the Pacific, the Marines would have to prepare for a succession of concentrated amphibious assaults. As the prescient Ellis well knew, such attacks would be met by fierce and organized Japanese resistance from hardened island positions. In words that would become prophecy, Ellis declared: “The landing will entirely succeed or fail practically on the beach.” 

Fatefully, Ellis would not live to see the theoretical battles that he studied with such vigor and diligence. In 1923, he died mysteriously on Palau Island while on a self-appointed reconnaissance mission to study existing Japanese defenses.  Nonetheless, his capstone research, eventually christened “Operation Plan 712: Advanced Base Operations in Micronesia,” formed the Corps’ interwar foundation of amphibious strategy and doctrine. In part, Ellis’s pioneering work helped advance the rising stature and expectations of the Marines. By 1927, a Navy Department directive specifically assigned amphibious landing operations to the Marine Corps, and in 1933, Navy General Order 241 reorganized the Corps as a Fleet Marine Force.

Marines Heading for Action: World War II

Through these bold bureaucratic moves—and in large part thanks to the energetic leadership and vision of Lejeune and Ellis—the Service found itself explicitly assigned and structured for its budding amphibious mission.

Source: "Getting the Shells to Fall Where You Want Them”; Marine Corps History, Summer 2020