Gunners dig in on captured territory during the Battle of Messines Ridge, 1917

Photograph, World War One, Western Front (1914-1918), 1917.

Members of the Royal Field Artillery with their 18-pounder field guns. Over 8,000 of these weapons were manufactured during the war and between them fired 100 million shells. With a crew of ten men, it could fire 18-pound shrapnel, high explosive or smoke shells up to six kilometres (over 6,500 yards). The recuperators (the mechanism that returned the gun barrel to its firing position after recoil) of these field guns were wound with thick rope for protection.

From an album of 76 official World War One photographs, 1916-1917.