Civ 4 warfare

Ok, /games/, how do I stop sucking so hard at Civ 4 offensive warfare?

I just reinstalled the game, and the same thing happened as always: I tried to wage war against a vastly inferior opponent in single player, and I couldn't take a single city.
The defense bonus is so huge, even when reducing city defenses to zero, I lose most of my units without doing much damage.
How are you supposed to do that? Sacrifice catapults to do some collateral damage?

Is there something obvious I'm missing, like maybe I should just roam around his country destroying roads and buildings?

I've never played this but I believe you need to pre-program some mentally retarded AI to guard some object that you should probably go look for.

4 SUCKZ

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