The battle book includes rules for a multi-player campaign, but this campaign has it's faults. For a start a player cannot actualy lose territories, and also there is no real experience system. Here is the system I have used a couple of times. It may well be simple and easy to use, but it can prove far more fun than a campaign where too much time is spent organising troop distribution, income, map movement, etc., and not enough time is spent fighting battles.