Old houses lean over the still waters of the Sambre River in occupied Charleroi, Belgium — a city that had already witnessed catastrophic fighting in August 1914 — while a German soldier named Wilhelm writes home to his brother Nikolaus in Sonderburg, Schleswig-Holstein, on June 9, 1916, using the wartime Feldpost mail system that kept the Kaiser's armies connected to their families across a continent at war. The card, published by Ern. Thill of Brussels and bearing a K.D. Feldpostamt (Royal German Field Post Office) cancel of the Garde-Reserve-Korps dated 11.6.16, is a direct artifact of the German occupation of Belgium during the First World War.