Well, I dunno if this is a strategy is what would normally be used for any faction, regardless of cav dependent or not. Usually if the comp ends up that close to me, they turn and run to a farther away position to make me have to march more. However, the comp is able to recognize all its units' stats in comparison to yours, and many times if it thinks that it can win, it'll charge and attack you, even if it is on defence. I don't know if that translates to the computer having a closer position when the battle starts. Hope that helps.