How women joined the World War One nursing effort

Nurses marching together during training.

When Congress declared war in April 1917, the United States had no sizable standing army. While volunteers were accepted, most men joined the military via a new draft.
To fulfill the need for a medical contingent, military officials knew they would need a huge number of doctors and nurses.
Many hospital staffs responded by forming their own volunteer groups. Without depriving the home front of medical personnel, these professionals called for their own in-house staffs to volunteer to serve abroad.
Among those who volunteered were nurses, many of them newly graduated from in-house hospital training schools.
Here, above, we see them marching together in their day uniforms.