2 rockets which were sent up to burn with a brilliant glare to light up men and other targets in the area between the front lines (See illustration, page 118 of Out in the Dark.)
3 a camp away from the front line where exhausted soldiers might rest for a few days, or longer
4 the noise made by the shells rushing through the air
5 outpaced, the soldiers have struggled beyond the reach of these shells which are now falling behind them as they struggle away from the scene of battle
6 Five-Nines – 5.9 calibre explosive shells
7 poison gas. From the symptoms it would appear to be chlorine or phosgene gas. The filling of the lungs with fluid had the same effects as when a person drowned
8 the early name for gas masks
9 a white chalky substance which can burn live tissue
10 the glass in the eyepieces of the gas masks
11 Owen probably meant flickering out like a candle or gurgling like water draining down a gutter, referring to the sounds in the throat of the choking man, or it might be a sound partly like stuttering and partly like gurgling
12 normally the regurgitated grass that cows chew; here a similar looking material was issuing from the soldier’s mouth
13 high zest – idealistic enthusiasm, keenly believing in the rightness of the idea
14 keen
15 see note 1