Trench warfare
Psychological impact

Nervous and mental breakdowns amongst soldiers were common, due to unrelenting shellfire and the claustrophobic trench environment. Men who suffered such intense breakdowns were often rendered completely immobile, and were often seen cowering low in the trenches, unable even to perform instinctive human responses such as running away or fighting back. This condition came to be known as " shell shock ", "war neurosis" or "battle hypnosis". Although trenches provided cover from shelling and small-arms fire, they also amplified the psychological effects of shell shock, as there was no way to escape a trench if shellfire was coming. If a soldier became too debilitated from shell shock, they were evacuated from the trench and hospitalized if possible. In some cases, shell shocked soldiers were executed for " cowardice " by their commanders as they became a liability. This was often done by a firing squad composed of their fellow soldiers – often from the same unit. Only years later would it be understood that such men were suffering from shell shock. During the war, 306 British soldiers were officially executed by their own side.
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