I have a system that includes Companies (200 men), regiments (1000 men), Brigades (5000) men, Battalions (20,000), and provisions for larger units. I read the comments this morning, and spent the day throwing together a rough RoE adaptation of the strategic level rules I am developing for my game.
Take a look at it, and if you like it, I'll tweak it and adjust it. I can, given a week or so, provide a automated battle calculator that will take into account all the various special abilities of the units.
The attached files are a PDF of the basic rules so far and an Excel file for determining the appropriate values for the Cirilean units as presented in the Regent's guide.
I know its not perfected, like I said, I threw it together over about 10 hours and a 12 of beer, but the basic outline is there -- it is a part of an over all adaptation of E-in-A for Birthright.
Let me know what you think -- it might be useful.