The White Nun was a member of a religious order worked in the hospital in Port-Gentil, French Equatorial Africa (modern-day Gabon) during World War I. She tended to the medical and spiritual needs of the patients and visitors. Her colleagues included the Black Nun, and the Army Doctor and 2nd Army Doctor.
In late December 1916 or early January 1917, she and the Black Nun were checking on patients and found a group of Belgian officers and soldiers, including Captain Henri Defense (Indiana Jones), Lt. Baudouin, and Privates Zimu and Juba, with an Ubangi orphan, visiting their comrade, Sergeant Barthélèmy, who had recently died of a gunshot wound. The nun apologized for not covering the sergeant's body out of respect, while her partner helped translate a message to the boy from Jones.
Given that she worked with patients in the hospital, it is likely that she had some basic education in nursing, as well as her role as a member of a Catholic order of nuns.
Behind the scenes
Maryon Fletcher played the role of the White Nun in the episode "German East Africa, December 1916" of The Young Indiana Jones Chronicles.