Unfortunately I think that would require either a script or a whole new set of db data designated specifically to the ai... or even both, as im not sure how the latter would work without, i.e. script triggers for who gets which set dependent on whether or not the faction is human. I think that would be a lot of work as im unfamiliar with R2 scripting and updates tend to break scripts...so I think the best we can do is give a somewhat fair standard for all factions with major cities having a
slight advantage vs minor settlements in terms of garrison makeup.
Proposal:
--Major cities will have a medium strength base garrison overall with a few strong units representative of the city culture (the idea--a peace keeping/repelling force lead by select veterans that head the military institutions of the city),
--Minor settlements will have a fairly large garrison of basic/medium units with a veteran elite unit, the makeup of the garrisons will be determined by the resource of the village (the idea--the artisans and hunters and farmers and fisherman arming themselves to defend their homes lead by veteran administrative/mercantile retainers)
--All military, port, religious, trade, administrative buildings will yield small numbers of elite units--1-2 max + 1-3 additional light supports-- at high tiers, 3+.
(the idea--each of these buildings has now grown in size and power with the city--they have become investments of the people and the organizations of men who operate/maintain them and thus warrant protecting. some examples: tier 3 barracks-->soldiers-in-training and their armsmasters-->militia hoplites + elite hoplite; tier 3 port-->shipwright's warship + patrol ships + fishing ships-->heavy tower penteres, pursuit and raider hemiolas... etc etc, I think you get it)
ALL BUILDINGS WILL PROVIDE SOME SORT OF GARRISON relative to what the building is and will evolve with the building--e.g. outskirts--> 4 politai hoplitai (the idea--local men recruited into the militia of the settlement); amphorae kiln--> 4 politai hoplitai, 1 theurophoroi (the idea--local men + private guard of the kiln(s) owner(s)); tier 3 amphorae--> 4 politai hoplitai, 1 theurophoroi, 1 swordsmen/marine (the idea--local men + private guard of the kiln(s) owner(s) + escorts/guards of the shipments/stores of amphoraes); and so on and so forth.
Mobs will be for the most part non-existent except for a few in cities... I find the utility of the mobs to be unrealistic... mobs would fight out of desperate self-interest/self-preservation but wouldn't really stand toe-to-toe with soldiers thus would break easy but always come back in hopes of victory IF and only if the odds were in their favor.
With these changes each settlement can have a unique diversity in its defender makeup and I think it being balanced is plausible, but if not, then at least conquering a territory will seem to have been logical; oh, this settlement was easy to conquer because it was a tier 1 fishing village with 2 economic buildings and a fishery, I was fighting fishwives and tradesmen! Gee that sure makes sense, and feels a lot better than, woop another

basic tier 1 garrison to autoresolve, yawnnnnn.


I want the garrisons to be comprehensive, that's all.
Thoughts?

I think I'd enjoy throwing something together.
