These are more for a late game war where the goal is to significantly reduce or totally eliminate an AI civ. Static Frontline: You have a well defended or small frontline and you wish to keep it. So you disband cities as you conquer them leaving an ever growing unclaimed patch of land. The advantage of this is you don't have to constantly check for border integrity at the end of each turn. Interesting observation, the AI never seems to build settlers while at war, any they happen to be building or have at the beginning of the war if used will be poorly defended and easily retaken. The challenge is to have enough settlers on hand to get you back in range of the next city to take each turn. I especiously like this when I have a choke point and can setup a funnel of death. Advancing Frontline: You keep or build new towns as you conquer to maintain border integrity. If you're starting with a long frontline and can move toward a shorter one this may be the way to go. In a Static Frontline you have to minimize units left on the battlefield because they are vulnerable. In an Advancing Frontline you can pretty much leave them unprotected. Its definitely all about border integrity. I don't know how many times I've left a single access point and since I never defend cities behind enemy lines its pretty discouraging when they take a dozen cities in one turn. Opinions? Other challenges/advantages? Other options?