I’m intrigued to see what you come up with, although I’m not entirely clear on how large the battles you are proposing are. Personally, I would not think in terms of ‘units’ but rather in terms of ‘battles’, i.e. larger formations composed of a number of contingents that you have to keep together for maximum effectiveness. Command and control would be key, with warlords being an essential element of that. I like the idea of heroes and warlords at the forefront of the fighting. It adds colour to the proceedings, as well as being important for morale. What self-respecting warrior would want to follow a warlord who does not lead from the front after all? However you decide to approach it, I hope you’ll post the rules here for us to see.