AI behavior towards combat odds

Predator145

Prince
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May 22, 2020
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We know the AI avoids taking very unwinnable fights. It will generally avoid fighting full health armies in the open. But for some reason would do so when the army defends a city.

When facing fortified infantry with cavalry, the AI would often try to bypass the infantry in the city to go for empty ones beyond its reach to be slaughtered by the player's cavalry the next turn. The odds of a cavalry vs infantry fortified in the open is 13.6%, behind a wall/city it's 6.7%. The latter is almost, always avoided. This makes this period in the tech tree to be the most advantageous for the human to fight the AI. You can hurt them with artillery, but they can't hurt you (at least as well with Flintlock's patch).

The AI will be happy to use horsemen to attack spears or cav vs rifles behind walls/city. The odds of these are 20.1%. A tank vs a fortified infantry in a metro on a hill has similar odds at 22.9%

What's the cut off point percentage to trigger the AI to avoid combat? I suspect at single digit. But it could be higher. We know for sure that at 20% they're ok to go.

I'm looking to add a bunch of city defenses. Right now with each of them providing 25% boost I'd end up with with a max boost of 300% with metro on hill and radar tower. That's a 4x boost. It's not that excessive considering the AI esp with offensive artillery enabled will usually be left with 2-3 defenders.

The rule of thumb for offense vs a prepared defensive position is 3:1 on avg. But that's not vs heavily fortified targets like medieval castles/walled cities or a modern urban environment. 10:1 is considered necessary for a large fortified major modern city with the pop of a couple million or more :

"A French military source told AFP that the rule of thumb was that attacking forces needed to outnumber defenders 10-1 because the defenders had the advantage of knowing the territory. Defenders can also benefit from the height advantages from local buildings, with tanks and other armoured vehicles vulnerable to attacks from above.

"It would be suicide to send tanks into urban areas," said Alexander Grinberg from the Israeli think-tank JISS. They can't maneuver or move around... To conquer cities, you need professional infantry that is very motivated because it is always very difficult."

Even for Constantinople the Ottomans needed a 10:1 superiority with the latest siege weapons. And there was long and brutal fighting.

On higher difficulties the AI certainly has the SOD to overwhelm the player's and each other's buffed static defenses esp if there are no choke points. But I'm afraid it would cause them to just try to bypass them with their fast attackers just to be wiped out by counter attacks next turn. Bypassing static defenses and racing to the exposed rear is a good idea in real life, but not in Civ3 where the home field defenders are much more mobile on their roads.

Making the AI more aggressive and willing to accept casualties to overwhelm a tough target would IMO improve their performance, considering they have overwhelming numbers.
 
I beg to differ. I do play virtually all my games on my modified scenarios, but I routinely have the AI attack full strength armies in the field, both with my enhanced Barbarian Units and with the AI player units. Those attacks may or may not be with bad combat odds. I also have had single AI units attacks my superior units in cities, and I have boosted the defensive factor of cities by quite a bit. This also occurs with either Barbarian units or player units. My normal Barbarian Units are the Gallic Swordsman with a +3 hit points and the Cossack with a plus +3 hit point to move them from Conscript to Regular combat experience. I have changed the combat experience table as well. This is in both Play the World and Conquests.
 
I've just tested with all settlement terrain giving 300% def bonus. The AI in the WW2 Pacific scenario does attack them. Japan suicided their veteran marines against fortified standard american riflemen. The odds of that were 18.7%. It's frustrating watching all those warships escorting the transports not bombarding.

Japan also pitted their vet nippon infantry vs standard fortified chinese infantry. The odds were 12.6%.

I then jacked it up to 500%. The AI would absolutely prefer other targets before the cities and destroyed every unit outside first. So I withdrew everything as the Chinese, but left the safe cities in the back empty. Xian did get attacked, still. A single standard infantry held off the entire assault. The odds were 5.5%. Those are cavalry vs infantry behind walls kind of odds. So the AI does attack very tough targets if no softer ones are available at these single digit odds.

But these single digit odds are still nothing compared to armies. A vet cav going up against a 16 HP cav army with military academy and pentagon has a 0.1% chance of winning. A vet cav vs a 12 HP knight army without military academy and pentagon has the odds of 4.2%. But I've never had my knight armies attacked by AI cavs. That's because their are softer targets ie my pikes/muskets behind walls. This way a single knight army can cover my treb stack. Had the escort been pikes/muskets I'd be losing units at a much faster rate every turn to cav hit and runs on my stack in the open marching slowly through enemy territory.

As long as their are softer targets around, the AI will avoid the tougher ones. That's how people create funnels of doom by leaving bait. But it's not the empty cities they're after, but the weaker units that they will get better odds against I think.
 
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You definitely are experiencing things differently from me. I am not sure why this would be. I have played the WW2 in the Pacific mod, both unmodified and my modified version, and that is not how the AI is behaving. The really strange thing in my latest game is no Pearl Harbor attack. The Philippines are hit immediately though.

Side Note: Does anyone have an unmodified biq for the WW2 in the Pacific scenario? I seem to have modified mine without keeping an unmodified copy.
 
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You definitely are experiencing things differently from me. I am not sure why this would be. I have played the WW2 in the Pacific mod, both unmodified and my modified version, and that is not how the AI is behaving. The really strange thing in my latest game is no Pearl Harbor attack. The Philippines are hit immediately though.

Side Note: Does anyone have an unmodified biq for the WW2 in the Pacific scenario? I seem to have modified mine without keeping an unmodified copy.
Here's an unmodded version attached.
 

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