Disclaimer: I'm using Ultimate Campaign rules, not direct Kingmaker rules.
I'm sure there's been a number of threads about raising army, what percentage of the population you can recruit, and other such things. I thought that what we could call "Military Strength" could be an edict just as promotion, taxation, and festivals are. I'll explain my proposal bellow in full and appreciate feedback in return.
Recruitment Level--Standing Army (% of pop)--Registered Militia (% of pop)--Economy--Stability
0--0%--5%--0--(-1)
1--1%--10%--(-1)--(1)
2--2%--15%--(-2)--(2)
3--3%--20%--(-4)--(3)
4--4%--25%--(-8)--(4)
Standing Army are lvl3 of the favorite PC class of the settlement.
If a settlement has a Military Academy, Standing Army is lvl5.
Militia are lvl2 warriors.
While other edicts are changed at whims of the rulers, a settlement can suffer penalties for changing Military Strength. For each level Military Strength is increased, attempt a loyalty check (DC = Control DC + new Recruitment Level) else unrest increases by 1 and loyalty takes a -1 penalty. This loyalty penalty persists until Military Strength is decreased or a loyalty check is reattempted on a following turn.
Military Strength is level 0 by default. It cannot be increased unless the settlement has one of the buildings listed bellow to train soldiers and militia.
Registered Militia are not payed until they are called into activity. Activity means they are called to defend their settlement for a battle (treated as if 1 week of active pay) or they are deployed and leave their settlement as an active army (treating them like a normal army).
Standing Armies follow compensation rules illustrated in mass combat (usually held in reserve status [see mass combat]). However, when the settlement or hex contains any of the following military buildings, only the reserved army population outstanding the building capacity consume BPs.
Barracks (200)
Castle (200)
Fort (500)
Garrison (400)
Military Academy (200)
Palace (50)
Watchtower (50)
Example, I've been running a single-city kingdom called New Imaskari, total population 9000. I've been playing a neutral faction, taking care of other people's banking and taking no sides in conflict, so I keep my Military Strength level at 1. My standing army is 90 and registered militia is 900. My city contains a garrison, so my standing army does not add to my consumption. I do take a -1 penalty to economy as my 900 registered militia take a few days off work every month to receive training, but I get a +1 to stability as the citizens feel more secure.
Then say a neighboring kingdom starts making threats are raising a army against me. In this state of emergency, I raise my Military Strength level to 4, increasing my standing army to 360 and my registered militia to 2250. I need to make 3 loyalty checks to quell unrest and maintain civilian confidence. Because 25% of my civilian base are taking time off to receive training, I take a -8 penalty to economy. Stability bonus increases to +4 as the city is on high alert. Since my standing army is in excess of reserve room in the garrison by 60, I treat the 60 as a normal kingmaker reserve army paying 1BP/turn. Were I to be attacked, I would fight with an army of 360 lvl3 unites and a militia force of 2250 lvl2 warriors. At the end of the battle, I would pay the surviving militia force as if they were an active army (say 1500 survive with an ACR between 5 and 7, thus compensation being about 3 for the fight.
Afterwards, I want to retaliate in full force against my offender. I maintain Military Strength at level 4 (keeping economy penalty at -8 as 1/4 my population is not working). I leave 500 militia at home (not increasing consumption) and hit the road with my standing army of say 300 and militia army of 1000, each increasing consumption by 2BP and 3BP, respectively, per week until they return home.)
Optional mechanic:
With a loyalty check and for occasion, a ruler may attempt to recruit a larger standing army or registered militia with a loyalty check. Success means the ruler can recruit standing army or registered militia above the listed percentage by 1/3 the check in excess of DC. (For example, if I have a Military Strength level of 1, I recruiting militia at 10%. If I make a loyalty check and surpass the DC by 6, I can increase recruitment by 2%, ceretis parabis.) Failure on this check changes nothing unless you fail by more than 6, in which case a third of the difference is subtracted from the percentile you can recruit.
Check out Ultimate Ruleship and Ultimate Battle from Legendary Games, its a third party publisher that has developed further on the kingdom building and mass combat systems.
Ultimate Rulership, Ultimate Battle, and Ultimate War; from Legendary Games covers all that and more.
Written by Jason Nelson, who did the original KM building rules, that Ultimate Campaign expands upon.
If you are using the Kingdom Building Rules, these are a must have.
EDIT: Ninga'd