Many thanks! I've just seen that there was a (very) light system to run mass combat in the first edition of Martial Law for Harp, so I think that even in the revised edition there will be some hints... For me that should be enough... I really love Harp: for me and so far Harp hits my sweet spot in terms of complexity, crunchiness, flexibility, completeness, character customization and playability.
Many thanks again!