:: World War I in color ::.

Lookout in the post of the lock 26. Serviceman Frenchman in observation. Eglingen. (Haut-Rhin. France. June 23rd, 1917).

Although color photography was around prior to 1903, the Lumière brothers, Auguste and Louis, patented the process in 1903 and developed the first color film in 1907. The French army was the primary source of color photos during the course of World War One.
http://www.worldwaronecolorphotos.com/