During World War I and the 1918 flu epidemic, she worked as a nurse and received the Croix de Guerre for her service.

She trained as a singer at the Conservatoire de Paris,[1] studying with teachers Martini and Jacques Isnardon.

[2] She appeared in London's Royal Opera House Covent Garden in 1910,[5] and recorded a duet in 1911.

She was decorated with the Croix de Guerre with the carte du combattant (signifying service under particular hazard) in 1920.

[12] After the war, Martyl created a charitable medical foundation with automobile racer Magdeleine Goüin, and the Nelly-Martyl Foundation's dispensary opened in 1929 in Paris; the building was razed in 2017, despite some efforts to preserve it.