Experienced battlefield hikers are familiar with the multi-tiered “Lager” or camps that the German Army built into the hillsides in the Meuse-Argonne.  Picture postcards of them can be easily found on the internet.  The concave holes in the hillside generally suggest that there was a camp or other German military installations present during the great war.  However, because of the passage of time, new growth, the absolute size of the camp, etc. it can be difficult to see the whole picture.

The link below shows the location of the “Borrieswald Lager” just outside of Apremont.  The image was produced using Lidar (Light Detection and Ranging) technology; and it enables the reader to clearly see the different terraces and the numerous hillside indentations, where the tunnels would have entered the hillside to provide relatively save sleeping and working areas for the troops.

http://centenaire.org/fr/cartographie/images-lidar-de-la-foret-dargonne

This camp is fairly accessible today:  Park at the Deutscher Soldatenfriendhof Apremont on top of le Chene Tondu.  Cross to the north side of the road and follow the forest trail (dotted line on IGN maps) down to the slope (i.e. contour lines.)

As a reminder, one such camp, the Morolager, has been restored and it is well worth a vist.