For the United States Marine Corps, participation in the World War, 1917-1918, was the single most important event in its development as an amphibious assault force during the interwar period between 1919 and 1941. While the Marine Corps experimented with what Marines called the "Advanced Base Force," built around the New Steel Navy during the first decade and a half of the twentieth century, that service spent the bulk of its efforts as a constabulary force in the West Indies and Central America enforcing the Monroe Doctrine and Roosevelt Corollary with minimal consideration being given to its role in the nation's defense. This changed, however, during the World War, as the tactical, operational, and technical innovations that characterized this conflict had a direct and lasting impact on the institutional framework of the Marine Corps during the interwar era. Led by Major General John A. Lejeune and a small group of far-sighted officers at Headquarters, the Marine Corps not only survived the fiscal conservatism of this era but instead thrived and built upon its World War record as a combat-ready institution.
This dissertation illustrates the impact of the World War on not only the Corps' advanced base force doctrine but more so the "institutional" or "day to day" operations of the Marine Corps insofar as training, education, recruitment, and administration are concerned. The participation in and lessons of the World War served as the basis for all of the reforms undertaken in the Marine Corps from the beginning of demobilization in early 1919 under Major General Commandant George Bamett through the era of Major General John H. Russell who served as the Major General Commandant from 1934 to 1936. The reforms enacted by General Barnett and his successors included the introduction of a permanent system of professional and vocational officer and enlisted education; training reforms; recruitment and retention of qualified manpower; and the slow, but steady acceptance of the landing mission as Marines returned from China in 1929, and Nicaragua in 1933 through the efforts of the Marine Corps Schools at Quantico. Taking the lead in all of these reforms were the innovations undertaken in the curriculum at the Marine Corps Schools at Quantico during the 1920's and early 1930's. The innovations introduced at Quantico had a lasting impact on the mission and doctrine of the Marine Corps as it began to prepare for its greater test during World War II.
Lastly, this dissertation concludes that participation in the World War had a far-reaching effect on the Marine Corps and its institutions, its personnel, and its operational and tactical doctrine. Institutionally, participation in the war changed forever how the Marine Corps would educate and train its officers and enlisted men; recruit suitable young men as administrators, supply clerks, aviation and auto mechanics, and most importantly, as infantrymen for its combat forces. The dissertation concludes that the World War's legacy inculcated a generation of officers who eventually led the Marine Corps during World War II in the principles of land warfare.