Help to identify what these crates were used for

[Phil my250gt]

Hi, wondering if anyone can shed some light on these boxes i just bought.

French I believe? 
some markings just about visible under the blue paint so thats not original then. Possibly brown paint underneath the blue. Yellow and white markings.

just wondering what age they maybe and what they were originally used for?

Im thinking possibly mortar shells? Would like to know what the markings mean.

Any info greatly appreciated.

[Citroman]

Hotchkiss-Brandt made mortars... maybe something to do with that?

[Le Prof]

The stencilling under the paint is for a box of five of these.

[Phil my250gt]

12 minutes ago, Le Prof said:

The stencilling under the paint is for a box of five of these.

Fantastic,  thats really interesting, thank you so much 👍