Letters played a vital part in troop morale during the First World War.
The logistics behind getting these letters to the front was quite complected with each combating nation having their own method of transportation. But the most common form of letter transportation fell in the hands of Pigeoneers who used messenger pigeons to carry letters back and forth from the front line. My Great Grandfather had served in a German pigeoneer regiment until he was injured by shrapnel in 1917.

Art by  ronff
Character by  Vick_Dastardly4