France: 14-18. Le Front, l'Arrière, la Mémoire

Today I got not only seven postcards but also two covers: one from France and one from Japan. 

Stamp:

personalised stamp

Inside were three postcards of the exhibition "14-18. Le Front, l'Arrière, la Mémoire" in the department Ille-et-Villaine in Bretagne.
During the World War I every fourth Breton going to war fell. That were 10 percent of the total population of the Bretagne. Generally "only" every eighth French fell. There were two main reasons for the high percentage. The first is that the Bretons fought forwardmost and second was that the Bretons mainly spoke Breton and thus the French thought that they were spies and killed them. 
The first card shows French hats and helmet used during World War I.
The Adrian helmet (upper row right) was the first standard helmet of the French Army. It was issued in 1915 as head wounds became a frequent cause of battlefield casualties in the trenches. Until 1917 7500 of them were produced every day.

The second card shows a voucher for having served in the army.

The last card shows bullet casings from the trench war.

Thank You very much Dominique!