D3nn16,
If you really want it to be a challenge, autoresolve every battle that does not contain your current faction leader. That would put you in the shoes of the leader of a nation, thus limiting what you can do to a larger extent.
This way you would have to plan things out a bit better ahead of time so that you go to fight those battles you think you really need to win while you entrust your generals to take over lesser settlements.
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