"If an army is in a city that can make the units it has, you can never defeat that army through attrition unless you can cause the enemy to run out of funds"

Can you retrain men in a city that is actually being besieged? I'm not quite sure - the times I tried it it didn't seem to work.

But anyway, I imagine a lot of this comes down to unit sizes. On huge and even large (though to a lesser extent) unless you have an absolutely enormous metropolis, you just don't have the population to replenish an armies ranks through more than a couple bloody battles. On the normal 40 man size, I imagine you could keep replenishing a full army from even a 13k population town for a looong time. But on huge, where you might lose 2k men per battle, it's not real feasible :)

Another point : I'm curious as to what 'attrition' you are referring too. Usually when I fight the AI, he gets crushed utterly. He'll lose 95% of his forces. I haven't really run into battles where we both fight, it's a draw, and we've each lost like 25% of our men. That at least is what I tend to think of as a battle of attrition. Maybe I am misunderstanding you.

But I do think it's odd you can recruit men from a town you just took - there should be some sort of flag that limits you from recruiting unless the culture penalty is at an appropriate level.

Also, perhaps degrading the level of military buildings by one (as often happened in MTW) might work.

But I do think this change helps the AI.

In MTW, I had armies of veterans. The AI always had armies of utter raw recruits.

In RTW, we both have armies of veterans.

In both cases the player would do whatever it took to make sure he had full strength veteran units, but in MTW, the AI almost never did.