JF Ptak Science Books Quick Post
See the WWI Photography section for more images and for an explanation of the source of the photographs.
This is a photograph of an aid station somewhere along the Western Front, 1917. Given the amount of digging going on throughout the course of the war, with the construction of hundreds of thousands of miles of trenches, and then the sapper war to tunnel underneath the tunnels and so on, it is quite possible that this underground shelter was dug out by hand. This is also an insight to the duration of some of those battles--to construct such a station impervious to possibly semi-continuous bombardment meant that the lines of battle were static, with many of the major engagements of hundreds of thousands of soldiers lasting for months, and in some cases, years.
The expressions here are difficult, and difficult to actually recognize as anything that isn't exhaustion. There is a lot of "blankness" in the faces, a deep weariness.
This scene is a detail from the larger and full image (which is also for sale at the blog's bookstore, here):