Concise description:
In two player games it seems that the default starting colors are always green and red. For color blind people, even with the letters in front of the colors, these are the most difficult colors to distinguish.
Specifics:
Red and Green mean that color blind people sometimes miss spotting an enemy army.
Blue and Yellow are much easier to distinguish.
Suggestion:
If it is not too ornerous a task, please change the defualt starting colours to Blue and Yellow for 2 player games.