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 crucial role during World War I, where he commanded the 2nd Division, a unit consisting of Marines and Army troops. Lejeune's leadership was significant because he effectively integrated Marine Corps tactics and training with the larger Army framework, showcasing the capabilities of the Marine Corps in a joint forces context.

His experience and historical impact went beyond just the battlefield, as he later became the Commandant of the Marine Corps and is remembered for shaping the organization during a transformative period. Lejeune's leadership style, innovative strategies, and focus on morale and discipline demonstrated the effectiveness of Marine Corps values in joint operations. This distinguished him not just in Marine Corps history but also in the broader context of U.S. military history.