Who is known as the "grand old man of the Marine Corps"?

The title "grand old man of the Marine Corps" is widely attributed to Archibald Henderson, who served as the Commandant of the Marine Corps from 1820 to 1859. His long and distinguished service significantly shaped the development of the Marine Corps during its formative years. Henderson is recognized for his efforts to professionalize the Corps, implement training and educational systems, and expand its role in military operations.

His leadership during critical periods, including the Mexican-American War, and his vision for the Marine Corps led to lasting changes that influenced its future. Because of these contributions and his status as a revered figure, he has earned the nickname that honors his pivotal role in the Corps' history. The other figures mentioned have their own contributions and significance within Marine Corps history, but none are as closely associated with that particular moniker as Henderson.