Fortresses and PTW - An Interesting Result

[Frank Johnson]

I've used this tactic serveral times in plain civ3.

The AI will pretty much ignore any heavily fortified location, city or not. If it is a city, they are much more likely to attack it if they can't reach another city however. I've seen the AI willing to attack a single infantry or 2 fortifted on a mountain side with tanks....but before tanks a single infantry on anything past hills is enough to deter entire stacks.

The meanest trick is not to wall up entirely though. Its just wall up everywhere else except where you want the whole enemy army to flow through. Then you can choose the site of the battle......and get them on horrible terrain and destroy them before they can get to your cities. You can also surround the stack or close the door in your line so theres no reinforcements or escape.

[Yahweh Sabaoth]

Catt, interesting observation on the AI's threshold for attack. Any thoughts on how # of defenders might affect the decision?

For example, say the Babylonians have tanks, and I have a fortress with 8 infantry, veteran, fortified on a hill. How many more infantry would I have to add to be a deterrent to the tanks, or would it even matter? (assume the tanks are veteran for this example)

[Frank Johnson]

I don't think the number of troops is involved in the choice to attack or not, but only in the selection of the target when multiple targets are offered.

The AI is driven by some goal, like attack that city, or pillage that resource. Then if there are units past the thershold limit in the way they will attack them. If there's alot of units in a line denying them from their goal, then first they'll check if the enemy is in the allowable attack range. In this case, tanks will attack fortified infantry on a mountain side, so unless you add a time consuming fort, you can't deter a tank from attacking.

Once its been determined that the targets are in the allowable attack range, the enemy will just attack the square with the least units on it, or if there's a variety of units it will attack weaker ones before stronger ones.

[Yahweh Sabaoth]

Really? So, if I have 30 infantry in a fort, and the AI has 5 tanks, they will still attack? That's quite insane.

Of course, the AI seems to rarely attack unless it has a healthy stack to attack with, but nonetheless, by the point in the game when tanks become availible, I think it's quite concievable that a human player with narrow borders could maintain a few fortresses of considerable strength (through numbers), considerable enough even to defeat the nasty tankses.

Anyone have any idea how many units the enemy must lose before it calls an offensive off? 50%? 75%?

[Frank Johnson]

You're right about the AI only moving with large stacks, that is, unless they see some oppertunity open up it can accomplish with less.

On your situation with 30 units in the fort.

#1 if the AI can in anyway walk around them to get to the goal they will.

#2 if theres any other fort with say 29, or 15 units in it, it'll attack that one instead too.

#3 if theres another fort with 30 riflemen in it instead they'll attack that one.

And on my point that the numbers don't determine weither they will attack or not.....its more clear if you go on the offensive. Ever had a stack of wounded armor sitting around outside an enemy city with 3 or 4 infantry on it just to take hits for them? The enemy sends out its few tanks to counter attack, even if they are hurting really bad and only have the ones they made this turn. Bang.....I lose 2 infantry. They couldn't take out the whole stack if they wanted to.....but they still fight back....so thats why they can't analize the whole stack vs stack insituation before hand. They have to at least fight back. Now its true there many be a number of losses at which an enemy will break off, but I think that is a completely different formula.

[Yahweh Sabaoth]

Hmmm.... interesting... so the implication is that the enemy had 10 knights, they would avoid 2 musketmen and head for 30 spearman instead, right?

[Catt]

Originally posted by Frank Johnson
The AI will pretty much ignore any heavily fortified location, city or not. If it is a city, they are much more likely to attack it if they can't reach another city however. I've seen the AI willing to attack a single infantry or 2 fortifted on a mountain side with tanks....but before tanks a single infantry on anything past hills is enough to deter entire stacks.

Originally posted by Yahweh Sabaoth
Catt, interesting observation on the AI's threshold for attack. Any thoughts on how # of defenders might affect the decision?

Originally posted by Frank Johnson
I don't think the number of troops is involved in the choice to attack or not, but only in the selection of the target when multiple targets are offered.

[. . .] In this case, tanks will attack fortified infantry on a mountain side, so unless you add a time consuming fort, you can't deter a tank from attacking.

Originally posted by Yahweh Sabaoth
Anyone have any idea how many units the enemy must lose before it calls an offensive off? 50%? 75%?

Good conversation. First off, from my perspective, the intriguing fact I gleaned from my initial observations (subsequently supported by Nathan's and badams52's posts) was that severe disparity in attack and defense values seems to result in an AI avoiding engagement, even if such avoidance means no fighting at all. We can build a series of fortifications to channel AI attacks into kill zones or simply to control specific, strategic locations (allowing AI attackers to bypass the location), but what was news to me was the ability to absolutely prevent attacks -- think about that -- a technologically equal (or better) human player can completely deter any attacks (except for seaborne invasions which are never a real threat) from a massively numerically superior foe. Imagine the potential strategic benefits of enjoying a 5 or 6 tile land border -- 12 or so defenders, in the right circumstances, can deter an attack by 60+ AI defenders (maybe lots more). With such a strategic position, the human could decide to (1) launch an offensive (if sufficient forces are available); (2) build up forces (without intervening losses) and then launch an offensive; (3) channel AI attackers into kill zones; or (4) do nothing! In the past, I would have believed that it was necessary to actively engage the AI - either defensively or offensively. What is intriguing is the option to do nothing - without losses, growing war weariness, military production needs, etc. Should you choose, for whatever reason, to continue along a path of "peaceful" isolationism, you are free to do so, unmindful of the military strength of your foes (for at least some period of time)!

Absent further examples, I agree with Frank Johnson -- the raw number of AI troops doesn't seem to be involved in the AI engagement calculation (witness my example of 60+ AI troops of "6" attack refusing to engage only 2 infantry). I don't necessarily think losses have anything to do with it either (though I am recalling Nathan's AAR in the AU "no war until communism game" when the AI called off an attack after some losses -- could it have been related to defender promotions?) It seems to me (and this is the principal reason I started the thread) that whether the AI force is hopelessly outnumbered or massively numerically superior, if the disparity between attack and defense values reaches a "break point," the AI will simply not engage.

Catt

[Frank Johnson]

That depends on the goal. ^_^

But......I've never seen that kind of situation before....but if in fact a musket man is good enough to keep knights from attacking, which I think they aren't, then yeah I think they would attack the spearmen.

Now if it was 2 infantry in the other fort......then I could say for certain the enemy knight stack would avoid them liek the plague.

[Catt]

Cross-posted with you both.

Originally posted by Yahweh Sabaoth
Hmmm.... interesting... so the implication is that the enemy had 10 knights, they would avoid 2 musketmen and head for 30 spearman instead, right?

@YS - I don't think the point is 2 musketmen versus 30 spearmen. We know the AI will seek out soft targets where available. And we know that the AI is not great about determining the likely success of an overall force or task group versus an opposing force or task group (Frank Johnson's point re: the few remaining tanks bouncing off a few infantry). What I found interesting is the fact that, even if the AI had 60 cavalry, if the only available target was 2 infantry (because map features cooperated), then the 60 cavalry would sit around unused -- the human could defend, without any losses -- with a force 1/30th the size of the AI force.

The questions for me are: (1) is there a hard-coded "no enegagement" break point based on "A" and "D" values; (2) if so, what is it; and (3) where, along the technology path, do equivalent attackers and defenders match up in such a way that the break point my be exploited (i.e., does a musketman in a fort on flatlands operate as absolute deterrance to knights or not? how about riflemen and cavalry?)

Catt

[Yahweh Sabaoth]

Vell Catt, you haf ze questions... now vere are ze answers???

[Frank Johnson]

I'm tempted to say that the only point in the game where this is really effective is with infantry vs pre-tank offensive units.

I guess you could also deter tanks by fortifying mech infantry on good terrain too, but then once modern armor came along they would fight those as well.

[Catt]

Originally posted by Yahweh Sabaoth
Vell Catt, you haf ze questions... now vere are ze answers???

I'm hoping to inspire someone with the thrist for knowledge and the requisite free time to conduct such tests and determine the answers

Although, to be honest, this is probably one of those tidbits of knowledge about how the game works that, although I don't consider it an "AI exploit," is something I would probably rather not know.

Originally posted by Frank Johnson
I'm tempted to say that the only point in the game where this is really effective is with infantry vs pre-tank offensive units.

I'm inclined to think the same thing -- the raw integers for A and D values of the earlier units just don't diverge enough for the % bonuses for things like forts, terrain, and fortification to bring the values so far out of whack.

Catt

[Yahweh Sabaoth]

I shall conduct some tests along these lines at some point. The answers are worth knowing.

Of course, I would prefer that someone without a job could conduct these tests, and leave me my spare time to put them into practice...

[badams52]

Originally posted by Catt

The questions for me are: (1) is there a hard-coded "no enegagement" break point based on "A" and "D" values; (2) if so, what is it; and (3) where, along the technology path, do equivalent attackers and defenders match up in such a way that the break point my be exploited (i.e., does a musketman in a fort on flatlands operate as absolute deterrance to knights or not? how about riflemen and cavalry?)

Hmmm, another example I have for you is the cavalry army I had which had 3 cavalry with 13 or 14 hp depending upon which one I was using. I noticed the AI never bothered to attack them through having infantry, so I used them for covering a solo cavalry unit (armies can't pillage ). Once the AI got tanks, he would attack my 14 hp cavalry army fortified in a forest.

Using Civlackey's combat calculator, it seems the tank would have almost 50% in the case stated above, but cavalry would have almost no chance by itself.

Taking this further (and using the calculator again) it seems the AI will never attack an MI army unless it gets below 12 hitpoints and he has elite MAs, or an army of MAs or Tanks. And an army of 3 infantry at 13 hp will be attacked on open terrain by elite tanks. Infantries with higher hp will be left alone till MAs. I would have mentioned armies with 4 units, but Civlackey's calculator doesn't allow that many hitpoints. This just goes to show a very important aspect of armies, they defend without being attacked.

Hmmm, I could be wrong, but I vaguely remember the AI using his cavalry one time to attack my army of tanks. Could have been injured though. I remember hoping it wouldn't be destroyed.

[Jaybe]

... (armies can't pillage ) ...

Yes they can (at least in PTW).