In the series about developing a little simulation for a landowner in fantasy pen&paper RPGs, I will write a bit about the next attribute: Military
This attribute represents the defensive and offensive abilities of the country. The players have to ensure the safety of the people if they want them to pay the taxes. So they need some guards to protect the villages and small cities. Guards for their castle are also part of the Military attribute. For that, there has to be a minimum in Military. The attribute can range from 0 to 10.
0 means that there are no guards at all protecting the people and the castle and all people have to protect themselves against all kind of threats ranging from wolves hunting for food to gnoll bandits raiding the villages.
The rating is reduced by 1 in terms of protecting the people and for an offensive, it's reduced by 2. So the protection of the castle is better than the protection of the villages and the defense is stronger than the offense, assuming that you still want to be able to defend without penalties.
If there are some attacks or defenses involving military troops then we have to look at the difference between attacker and defender rating. I won't write here fixed numbers of troops because it depends on the playing style of the group and the DM (here me) and how big they want it to be. If they want to have big troops marching up to fight hundreds of enemies the number of troops for each rating point has to be bigger than when they want small skirmishes with groups of 5-10 people.
So it's better to look at the ratings and modify the battle depending on which side has the better rating. If both have the same rating then the strength of both sides will be equal. If one side has a lower rating I would reduce the battle strength by either reducing the number of troops or their quality. Per point difference, I would reduce the strength by ~10% (adding troops to the stronger side is also possible).
Because battles always take a lot of time the outcome can also be decided by a simple dice roll (if the players aren't involved directly).
If the difference between attacker and defender is 0 then the attacker wins 50% of the battles, using a D10 the attacker wins on a 1-5. With a difference of 1 the attacker wins 60%, on a D10 the attacker wins on a 1-6. The maximum is obviously 100% or a rating difference of 5.
For example, I have Military 4 and one of my villages gets attacked by a group of gnoll bandits. The bandits have a rating of 2. My rating for defending the village gets reduced by 1 because the village guards are a bit weaker than the ones in defending the castle. I have a defense rating of 3 and the bandits an attacking rating of 2: the difference is +1 for me and the chance to win the defense is 60%.
What happens after a battle is won or lost is up to the DM. Let's use the example with the gnoll bandits. If my village guards successfully fought against the gnolls I would give a small bonus like some special items or use it as an opportunity to create a little quest: the gnoll bandits fled back to their camp to recover - the players can try to attack them to get their treasures or maybe some information about a magical item in a temple ruin.
If the gnolls won their attack they successfully raided the village and I would reduce Morale or Wealth by 1 until the gnoll bandits get stopped.
Using Military for an attack
Once per turn it's possible to send troops for an attack. The attack rating is the Military rating reduced by 2. With Military 4 the attack has a rating of 2. Raiding something offers the chance to get more Wealth, some treasures or it's used to neutralize threats like the gnoll bandits. These kind of attacks are standard actions which don't cost extra resources.
Bigger attacks are also possible but they should cost Wealth or even reduce the Military attribute. A big offensive also takes more time - at least one turn to prepare it. The advantages of such a big offensive are a higher attack rating: full military rating or even more if more resources are used. Such an attack costs 1 Wealth. Using another point Wealth adds 1 Military rating for the attack (the money is used for upgrading weapons and hiring mercenaries). The maximum is +2 for the attack.
Phew, I think it's enough for the moment ^^. It starts to become a game within a game. A lot of these rules can be modified or simply try to improvise on the go and use them as little guidelines. The important parts are some numbers showing the players the current condition of their country and the possibility to compare it with other countries. The rest can be improvised by the DM on the go if it's too complicated. But you will have noticed that I really love to have a lot of rules to cover some possibilities.