Prior to World War I, Marine Officers primarily came from the Naval Academy, or were commissioned from the enlisted ranks, but as the Marine Corps expanded it needed its own training pipeline for officers.
Marine Officers primarily came from the Naval Academy. This was prior to World War I. Marine Officers were commissioned from the enlisted ranks. This was prior to World War I. Marine Officers were. This was prior to World War I. The Marine Corps expanded. It needed its own training pipeline for officers.