Pvt. Opha May Johnson, first enlisted female Marine sometime after joining the Marine Corps. Johnson enlisted into the reserve in August of 1918, as a 40-year-old. (Courtesy of the Marine Corps History Division, Historical Reference Branch) - Pvt. Opha May Johnson, first enlisted female Marine sometime after joining the Marine Corps. Johnson enlisted into the reserve in August of 1918, as a 40-year-old. (Courtesy of the Marine Corps History Division, Historical Reference Branch)