Here are a few photos of the helmets in use in WWI, typically covered, and an impressive painting.
Photos and caption from here on the internet -
https://en.wikipedia.org/wiki/French_cavalry_during_World_War_I
Dragoons bringing back German prisoners on August 24, 1914. Police duties were then part of the cavalry's missions during military operations.
A Saint-Étienne model 1907 machine gun used by dragoons during the major maneuvers of 1913.
Reconnaissance riders: one of the main missions of the cavalry in 1914.
French dragoons in column near Montmort-Lucy (in the Marne) in September 1914. The campaign uniform includes a canvas helmet cover, to avoid metallic reflections which can be seen from a distance.
The Stars, a "patriotic" painting by Eugène Chaperon dated 1914 depicting the French defeat of 1871. It shows a French dragoon in front of a Prussian Uhlan, both armed with lances.
