This French Sapeurs-pompiers helmet is designed in the style of the legendary Adrian helmet pattern was a combat helmet issued to the French Army during World War One. They were eventually replaced at the end of WW2 with a more supportive and protective style.
The helmet is missing a front plate which would have had a castle with flaming bomb in shield surrounded by oak leaf branches and beneath a scroll banner that reads SAPEUR POMPIERS L'HOTELLERE.