In 1914, soldiers marching off to war were issued with a kitbag holding essential clothing and equipment such as wire cutters, waterproof map holders, field glasses and a fob watch, amongst many other things.
A watch was an indispensible part of military kit because, before modern radio systems came into play during war, operations across vast battlefields were synchronised by time. "The attack will begin at 0600 hours".
Fob watches issued by the Army proved to be impractical in the trenches; to see the face, a soldier would have to put down his gun and use both hands to retrieve it, leaving him unarmed. Fob watches were not waterproof and had glass faces that shattered easily, sometimes causing injury.
They could not be seen in the dark, and soldiers would have to strike a match to see the time, dangerous because of the ever present risk of a sniper's bullet. (This gave rise to the habit among cigarette smoking infantry of never lighting three cigarettes from one match because it gave time for a sniper to focus on the light and pick off the third man.)
For these reasons, soldiers often purchased their own wristwatches which provided the much needed resilience, legibility, luminosity and accuracy, and came to be known as trench watches.
