There are calls for help identifying the nurses in the collection of photographs (Image English Heritage).
Rare photographs of World War One's "forgotten" nurses have been colourised to help trace their identities.
Researchers at English Heritage are calling on the public to assist in identifying the nurses of the Great War who worked at England's first wartime country house hospital at Wrest Park in Bedfordshire.
There are no formal records of the nurses who worked there.
English Heritage, who now owns the building, said they were the "backbone" of the military hospital, adding that they "deserve to be known as individuals, just as the soldiers they cared for do".
It ran as a hospital from 1914 to 1916 and was forced to close after a fire.
The original photographs have been transformed into colour images in the hope relatives might recognise their ancestors.
Andrew Hann, Lead Properties Historian at English Heritage, said:
"These women were the backbone of the hospital, and indeed the war effort, providing much needed treatment to the wounded, but also acting as a comfort to those soldiers traumatised by the horrors of war."
He added: "They worked tirelessly and deserve to be known as individuals, just as the soldiers they cared for do."
Mr Hann said a team of volunteer historians have "hit a brick wall" in finding out more about the staff who worked at the military hospital.
There were up to 24 nurses at any one time in the house, caring for 150-200 patients
Marina Amaral, a digital colourist behind the transformation of the images, said:
"These women did remarkable jobs during the First World War and if my coloured images help people recognise their family members then that would be an amazing outcome.”