German machine-gun position, trenches at Neuve Chapelle, 10 March 1915. According to the original caption, this machine-gun inflicted heavy losses on the 2/Scottish Rifles, an action described in John Baynes' book Morale: A Study of Men and Courage. The gun was set clearly into the parapet, and its position might have been visible before the attack; its smoke and flash would have been clearly visible during the attack, even if it had been set up for flanking fire. The effects of a howitzer shell on the machine-gun are clear, and the original caption says that the direct hit occurred only in the second bombardment, after the original attack had been stopped.
Source: IWM photo Q49208.