Here is what Firaxis themselves says about combat in Civ III. Source:
http://www.firaxis.com/civ3/gameupdate.cfm?updatenum=1
"In Civilization III, we continue to expand the combat system to make it a deeper part of the experience. Civilization III will have a combat system rich in fun choices that enhances the experience of planning and executing military campaigns. Here are just a few examples of how we are achieving this:
Great nations can produce gifted leaders from history, each one capable of leading your civilization to martial glory. Whether helming an army on a distant battlefield or passing their personal experiences onto future generations of soldiers, these towering figures can single-handedly alter the course of history.
Increased technological finesse can be found in Civilization III's reworked Zone of Control rules. No longer can a Phalanx hold a vulnerable pass as effectively as a mechanized infantry regiment. The ability to intervene in surrounding terrain is now determined by mobility and ranged weaponry, rather than the universal privilege of being just any military unit.
In CivIII, ranged weapons such as catapults, artillery and battleships can bombard enemy fortifications such as city walls and fortresses. This allows for a general 'softening' of defenses, which provides a substantial bonus to direct-fire units.
These are just a few of the many new features Civilization III incorporates to make combat a more compelling and fun part of the game."
