Who was the first Marine to lead an Army division into battle?

The first Marine to lead an Army division into battle was General John A. Lejeune. He played a significant role during World War I, particularly noted for his leadership during the Meuse-Argonne Offensive. Lejeune's contributions to both the Marine Corps and the broader military efforts showcased the distinctive capabilities and leadership qualities of Marines when integrated within larger Army formations. His success as a commander highlighted the versatility and effectiveness of Marine leadership in joint operations, setting a precedent for future cooperation between the Marine Corps and the Army.

In contrast, other figures in the options, such as General George S. Patton, were prominent Army leaders known for their tank warfare tactics and significant contributions to World War II, but they did not serve in a Marine capacity. Colonel William H. Rupertus was notable in his own right for various accomplishments during World War II but did not achieve the distinction of leading an Army division, while General James F. Amos served primarily as a Commandant of the Marine Corps, not as a divisional commander in battle. This historical context illustrates why Lejeune's achievements are particularly significant in Marine Corps history.