Aerial Photo of the Somme battlefield, showing railroad and shelters

Aerial photo taken over the Somme by a French lieutenant. The photo has been marked to show the position of shelters, railroads, and the estimated location of "La grotte du dragon," or "Cave of the dragon," which was a old stone quarry turned underground baracks during the war. French troops recaptured most of the cave from Germans in June of 1917, several months after this photo was taken, though for a period both German and French troops occupied different areas of the quarry's underground cave system.