Dump of empty shell cases, Fricourt, September 1916. These are 18-pounder shell cases, the byproducts of creeping barrages and wire-cutting. Since they were made brass, they were recycled two to four times, which is why they were collected in dumps. During 1916 the BEF fired several million 18-pounder rounds, so these cases are only a tiny fraction of the total.
Source: IWM photo Q1471.