Currently ranged units are so extremely powerful that there is little use getting anything but the minimum infantry needed to hold off the enemy for a turn while archers slaughter everything else. Even when they get into melee, often times they do not flee from the lack of infantry cover, instead just sitting back and shooting as defenders sit and let the enemy shoot them. It's extremely frustrating, especially when your side SHOULD have enough strength to defeat an enemy army, but confusing mechanics make trying to lead an army a crapshoot.