Victory by Preaching?

[The_Maxx]

I just played a game with a friend where I was Jotun and he was Pangea.

We placed 5 impossible AI's and 1 difficult AI. The difficult AI being Ermor.

Now, as I was expanding I ran into the feared Ermor empire (I hate them with a passion). So naturally I immediately drive my armies into their territories wiping them out. But, as always when I finally reached their capital province and layed down my siege with about a dozen nefel Jarls and some minor priests I cannot for the life of me destroy them. They always had about 24 commanders break my sieges where they would simply cast an army of undead to rout my soldiers.

But im persistant, I constantly regroup and siege again in the hopes of whittling down their commanders. They are in a situation where they cant afford any new commanders and the capital province being their only remaining fortress I thought I could win by the weight of my commanders vs theirs.

I managed to get them down to 14 commanders left...until I made a fatal error and basically lost the game (another story altogether). BUT, my friend mentioned that I may be able to preach to a victory.

So, to finally state my question. If your opponent has no remaining provinces besides their capital can you preach out their remaining dominion to ultimately destroy them?
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IE no dominion left, they automatically lose.