Who commanded an Army Division as the first Marine officer during World War I?

General John A. Lejeune holds the distinction of being the first Marine officer to command an Army Division during World War I, specifically the 2nd Division. His leadership was pivotal during some of the most intense battles of the war, such as the Battle of Belleau Wood. Lejeune's ability to integrate Marines into the Army structure showcased the adaptability and capabilities of the Marine Corps, solidifying its importance in combined arms operations.

Lejeune's command was significant not only for military strategy but also for elevating the reputation of the Marine Corps in the eyes of the Army and Allied forces. His approach to leadership, emphasizing swift mobility and aggressive tactics, gave rise to modern Marine Corps operational concepts. His illustrious career continued to influence the Marines long after the war, setting a high standard for future officers.

While the other individuals listed also made substantial contributions to military history, none commanded an Army Division during World War I as Lejeune did, marking his accomplishment as a significant milestone in Marine Corps history.