Men, Women and Guns by H.C. McNeile

No one who has ever given the matter a moment's thought would deny, I suppose, that a regiment without discipline is like a ship without a rudder. True as that fact has always been, it is doubly so now, when men are exposed to mental and physical shocks such as have never before been thought of.

The condition of a man's brain after he has sat in a trench and suffered an intensive bombardment for two or three hours can only be described by one word, and that is -- numbed. The actual physical concussion, apart altogether from the mental terror, caused by the bursting of a succession of large shells in a man's vicinity, temporarily robs him of the use of his thinking faculties. He becomes half-stunned, dazed; his limbs twitch convulsively and involuntarily; he mutters foolishly -- he becomes incoherent. Starting with fright he passes through that stage, passes beyond it into a condition bordering on coma; and when a man is in that condition he is not responsible for his actions. His brain has ceased to work.