General Information: The badge with the rod of Asclepius was for medical services (service de santé). (See French Model 1915). This badge was one of eight statutory badges authorized for use by different branches of the French armed forces.
An interesting side note is that the French medical services used the rod of Asclepius, the Greek god of healing, to represent their medical services. This is a snake wrapped around a rod. In the United States medical services are represented by the caduceus which is the symbol of the Greek god Hermes. The caduceus is two snakes wrapped around a rod that is sometimes represented with wings. The French symbol is correct; The American symbol is incorrect. The error was result of a now well-documented mistake caused by a misunderstanding of the symbology of classical culture. At any rate, too late to change it now!
Displayed Example: This is one of my last remaining steel helmets that came from my father’s collection. It is a French medical services helmet with an officer’s private purchase chinstrap. It is a size B, or medium size.
Collector Notes: If you were to rate the eight WWI statutory helmets used by the French in terms of rarity, the medical services helmets would fall somewhere in the middle. They are not that easy to find, but they do turn up from time to time.
* “Chain screens on steel helmet to protect soldiers’ eyes from fragments of shell, rock, etc.; manufactured by E. J. Codd Company, Baltimore, Maryland. E. J. Codd Company.” War Department. American Unofficial Collection of World War I Photographs, 1917 – 1918. Local Identifier: 165-WW-192B(3). National Archives Identifier: 533656. Ca. 1918. National Archives.
 “Caduceus as a symbol of medicine.” Wikipedia. https://en.wikipedia.org/wiki/Caduceus_as_a_symbol_of_medicine