My arche seleukeia campaign

[Titus Marcellus Scato]

I used to do the same, but it may be something of an exploit. I suspect that the A.I. is programmed to march its armies at your cities, and when it can't reach a city (due to your fort blocking its path) it gets confused and gives up. It will only attack the fort itself when it has LOS on it. It's nice to have a docile A.I. for a change, but if my hypothesis is right, this will prevent "reasonable" wars as well as pointless ones.

Ludens:

What do you mean, the AI will only attack the fort when it has LOS on it? What's 'LOS'?

[Ludens]

Line-of-sight. Basically, the A.I. seems reluctant to target forts, while often making opportunistic attacks on cities. My guess is the A.I. has to see a fort in order to be able to target it. It does not remember the location of forts, unlike cities.

[Arjos]

Yes best places for forts are near borders, where the geography covers sides, otherwise they just get bypassed...
Also if you are fabulously rich and can afford katapeltai, the AI seems to avoid those as a plague :D

[Titus Marcellus Scato]

Line-of-sight. Basically, the A.I. seems reluctant to target forts, while often making opportunistic attacks on cities. My guess is the A.I. has to see a fort in order to be able to target it. It does not remember the location of forts, unlike cities.

So, maybe enemy spies and diplomats don't report the location of forts, like they do cities.

But if a fort is on the natural shortest route from an enemy city to one of your cities, and can't be bypassed, and an enemy army marches along that route, it should see the fort, and attack it, right?

Maybe enemy armies that are only 'exploring' your lands because they don't know what's there won't attack your forts, but if they're trying to get to one of your cities and the fort is in the way, they will attack?

This seems about right to me.

[ayekides]

Its honestly hard for me to say how the A.I. reacts to forts. For instance with the Getai, they had Ak-Ink and I had the territory immediatly to the west (Vindobona maybe), I had 3 forts surrounding on the side of the land that belonged to me, but is literally 2-3 tiles away from Ak-Ink. I had other forts like this at various places which would have been immediately visible from Getai cities for large periods of the game.

On the other hand I did remember seeing a few 1-3 unit stacks that wold walk from one blockaded river pass one turn and then around to another one the next and so on, Kinda like they were constantly checking the defences, but possibly just the A.I. constantly forgetting that they exsisted there and unwilling to risk attacking them with a small stack?

Either way I recommend using forts if you play like I do, I usually will not expand past my factions victory condition borders until I have captured them all, only then will I expand farther and by then I'm usually so powerful that I begin to lose interest.

But when the Getai did finally turn on me, they tried to bring the hate. I'm talking 4-5 full stacks of Getai tired of losing to those awesome respawning rebel stacks north of them.

[Ludens]

So, maybe enemy spies and diplomats don't report the location of forts, like they do cities.

But if a fort is on the natural shortest route from an enemy city to one of your cities, and can't be bypassed, and an enemy army marches along that route, it should see the fort, and attack it, right?

Maybe enemy armies that are only 'exploring' your lands because they don't know what's there won't attack your forts, but if they're trying to get to one of your cities and the fort is in the way, they will attack?

This seems about right to me.

What I meant is that the A.I. needs to have direct line-of-sight (i.e. a unit or agent standing near to it) on your fort before it will consider attacking it. Sorry for being unclear. I am pretty sure the A.I. sees the same campaign map as we do; I just think it ignores forts unless it has visibility over them. This is not entirely stupid, since forts disappear when left unoccupied.

I am speculating on how the A.I. uses armies, but I suppose it assembles a task-force with a mission in mind. If this mission is capturing a city, the army will presumably ignore other targets, such as forts. If this is correct (and that's a big if); when a fort blocks the armies path towards the target city, the A.I. will stop, reassess its route, conclude it is too long, and give up. I am pretty sure the A.I. is not so complex that it can decide to destroy the fort as a step on the way to taking a city.

Of course, once the A.I. has given up on reaching the city, it might well decide to have the army attack the fort. But I think the A.I. won't declare war for the sake of attacking a fort. For the sake of capturing a city, yes, but not a fort. And, as I wrote, I don't think the A.I. is complex enough to see taking a fort as a means towards conquering a city.


ETA: I just realised I am contradicting myself here. If the A.I. is unwilling to declare war by attacking a fort, then that would explain why a blocking fort is so effective at preventing attacks. The LOS-explanation is not required, and, going by ayekides' experiences, not sufficient to explain this.

[Titus Marcellus Scato]

I am speculating on how the A.I. uses armies, but I suppose it assembles a task-force with a mission in mind. If this mission is capturing a city, the army will presumably ignore other targets, such as forts. If this is correct (and that's a big if); when a fort blocks the armies path towards the target city, the A.I. will stop, reassess its route, conclude it is too long, and give up. I am pretty sure the A.I. is not so complex that it can decide to destroy the fort as a step on the way to taking a city.

Of course, once the A.I. has given up on reaching the city, it might well decide to have the army attack the fort. But I think the A.I. won't declare war for the sake of attacking a fort. For the sake of capturing a city, yes, but not a fort. And, as I wrote, I don't think the A.I. is complex enough to see taking a fort as a means towards conquering a city.

ETA: I just realised I am contradicting myself here. If the A.I. is unwilling to declare war by attacking a fort, then that would explain why a blocking fort is so effective at preventing attacks. The LOS-explanation is not required, and, going by ayekides' experiences, not sufficient to explain this.

This makes a lot of sense, Ludens, thanks very much. So forts help deter enemy invasions, that's actually quite historically accurate.