For nation roleplay, I just use a simple formula to figure who wins. I take the number of troops (Lets say 2000) multiplied by .2, then I take that number multiplied by their army morale (depending on the country but I will use the base of 3) then divided by the opponents morale (Just go with 2). I also use an outnumbered multiplier, but I won't calculate that. So we get,

2000 * .2 = 400 * 3 = 1200 / 2 = 600 This is how many men the army can kill.