I am an amateur texture artist working for mod projects in my spare time. Currently I am the lead developer of “The Great War 1918” team, a WW1 modification for Company of Heroes (as texture artist, historian, designer and code monkey). I also assist the Verdun Online project as historian, an indie FPS game project set in WW1. Amongst other projects I made textures for "His Righteous Mod" (under the nick Grenadier), a modification for Dawn of War.
Some WW1-era rank and branch insignia charts I made as reference.
I actually made those of all the major belligerents; they've just not been set up in charts yet. I might add them over time.