Each roll being one in a sequence (ie one fight = one sequence), instead of being random 0 to 1 (actually * 1000, just easier to explain on 0-1), they go like this:
1/2, 1/4, 3/4, 1/8, 7/8, 3/8, 5/8, 1/16, 15/16, 7/16, 9/16, 3/16, 13/16, 5/16, 11/16, 1/32, 31/32, and so on (using binary counting which I was kind of proud to find as a "clever" way to generate that, getting older and such

)
In C2C this applies to both attacker and defender actually (both rolls it seems).
So the more and smaller rounds, the more accurate, but all in all, you already get the expected outcome +/- some "small" unexpected hp loss due to "rounding".
The advantage of the method is that it is NOT a new combat mechanic (just rolls average sequence), and it can be applied to nearly every combat mod in civ4 without changing its own cool mechanics. You just get the average of the mechanic, each sequence. It only requires rounds per fight to be large enough so the "rounding" is small enough.