Is there really such a big difference between a hundred gnolls armed with spears and a hundred French spearmen? I’ve been really enthused about the Field of Glory rules from Osprey Publishing since I bought them, and I am thinking, naturally, of how to apply them to battles in the Flanaess. I can think of nothing more exciting than to see a host of the troops of the Overking arrayed on a table against the combined forces of the Iron League, and I think Field of Glory would be a great rules set to use, even if it is not designed for use with fantasy.
My thinking is that it should be able to get most of the “fantasy” units described in real-world terms. Orcs and hobgoblins are drilled, gnolls are not drilled (the former being lawful in alignment, the latter being chaotic), and matching armor and weapons should be easy enough. The Overking’s Elite Guards are easy enough to classify in an army list, and overall parallels between the Flanaess and medieval Europe should be easy enough to make. The point being, there doesn’t need to be a special set of rules just to deal with non-human troops. A few special exceptions may exist, but no more than are needed for real-world troop types (skeletons are only half as likely to be affected by swordsmen and the like, for example, and never have to check morale). Details such as armor class, hit dice, etc. are easily taken care of by using armor type, quality and training, etc.
That leaves the impact of specifically magical effects such as dragons, elementals, and high-powered spellcasters. That’s a little trickier, but I think that delving back to the Chainmail Fantasy Supplement or Swords & Spells might prove beneficial. More when I have a chance to do a little digging.