Here's the situation (you should look at my ADM Modification thread first; the Attack and Defense Values are that of the mod):

I'm using a veteran modern armor (60.35) and I'm attacking a city with a population of 6 with an infantry on it (20.20). It seems like I have a higher chance of losing, and I once brought two over and they both got destroyed. Of course I got mad and reloaded the auto-save game.

Now here's another situation: The AI brings a rifleman (14.14) to attack one of my cities with an infantry unit (20.20). The Infantry couldn't even get two hits on the Rifleman, and I lost the city.

My reason for saying all this is because I think that the AI has an advantage over the human when it comes to attacking and defending cities. Normal combat is, well, normal. AI's have a fair match against each other. This is my opinion, and I want to know if I'm just dreaming of if it's true.

In short, you are dreaming. Very extensive and careful tests have been done that demonstrated pretty much conclusively that the combat system is precisely fair and gives no advantage to the AI. 'Surprising' results like this are invariably due to either bad luck or a lack of understanding of the combat system.

I bet it's a lack of understanding. It's a very hard system to understand. If I could get a full explanation of it I'd be happy.

Does playing of Chieftain make a difference of any sort, or do infantry have some sort of advantage over tanks?

No, no units have any special advantages over any other. Difficulty levels make no difference whatsoever either (unless its vs barbs). The system is not too hard; well, mebbe it is pretty hard, but there really aren't any hidden mechanisms in there to make certain things work one way, or have certain advantages.

Fortified 20.20 infantry would have 25 def, 35 if fortified behind city walls, 45 if fortified behind city walls and across a river, and 55 if fortified on a hill behind city walls across a river. It stands a fairly good shot at beating the MA. And then, after that, the hit points also come into play. If it is a veteran/elite infantry, vs a regular MA, it has a still greater chance. Lastly, the RNG comes in, so it could just be a stroke of bad luck that you had.

City walls don't have an effect when the population of the city is over two. If that's a stroke of bad luck, then I must just be an unlucky civver! :confused:

I had the same problem before I changed the values (24 vs 10). Using the Calculator on this site, an Infantry (this is the normal 6.10 now) fortified in a city on grasslands has a defensive value of 18.5, while the modern armor has an attack of 24. It says the Modern Armor has a 64% chance of winning and the infantry a 36%.

That's an 85% defensive bonus, which should give the infantry in my mod a defense of 37, against an attack of 60. I just need the odds of that calculated....

If the infantry is in a metropolis, he'll get a total of 135% for defense. That gives him a defense of 47. It's safe to say that it does equal out and it does make sense.

City walls have an effect until size 7, when the town becomes a city and gets a automatic 50% defense bonus.

There is still the matter of the RNG that has to be considered with every battle.

I'm not sure how to calculate the odds, since several factors play in (the defense, the hit points). You could try asking some of the creators of the various combat calcs how odds are calculated.

I found a calculator. I'm going to use it to find the values that balance the game.