Inside the red building, move a little to the left and find this item on a bed in the background.
"Dear Mister Dienstahl,
I have been held in a prisoner-of-war camp in Reims for almost 3 months now. We are relatively well treated, but I can't wait to get out of here. With your permission, at the end of the war, I would very much like to return to my foreman position. I still have all my faculties and even if I may not be as strong as I was, I'd soon be fit enough to work again.
I look forward to hearing from you,