Have you tried to go through the 3rd Party Art Mods Forum section? If not, it can be found here:
https://www.theblitz.club/message_boards...hp?fid=263
The color of the unit on the counters should help you out.
Red = Artillery
Yellow = Cavalry
Green = Infantry
I can't remember if the stock version Overland uses Blue/Grey colored 2D counters or it uses the Blue/Butternut color. I like to use Blue/Butternut so I am not sure if I have altered my stock files or not.
In some 3rd party mods, you may see Blue used to represent Infantry instead of Green.