So one of the issues here is that a player can leave a single infantry in a contested territory as a rear guard, holding up the advance of, say, 20 infantry and 10 artillery for an entire turn. Well, here’s a possibility:
If combat takes place in a contested territory, and the player whose turn it is scores enough hits to kill each defending unit at least 3 times, that player can advance any or all of his victorious units into a new enemy controlled territory, initiating a new combat.