"The advance continued on July 21 as the German Army fell back across a broad front in a general retreat. [There was stiff German resistance along the "Berta Line" in the area of Epieds, which included orders for enemy artillery to contaminate the front line with mixed gas of all types." "Epieds is reached by a valley from the south through which runs the main road. North of Epieds is a wooded hill, and to the west similar hills at the lower end of the Bois de Chatelet, and to the east other hills up to the northern end of the Boise de Trungy."