How does the AI calculate whether to sue for peace?

[Aodh Mór Ó Néill]

I remember reading here somewhere that there's an invisible AI "counter" that makes them ask for peace once it reaches a certain level. How exactly does this work? Does taking cities affect it more than battles/blockades? Does raiding and devastation have any effect?

[Lusitanio]

Usually things like battles (defeats), sieges and blockades influence that.

[QuintusSertorius]

Yes it does, and that calculation depends on which "state" it is in. There are two AI states, "diplomacy" and "warlike" with a script which triggers the switch between the two. Defeats, being besieged, heavy recruitment and so on increase "war weariness" which past a certain threshold with flip them to diplomacy. Once in diplomacy, they will randomly flip back again to warlike and start the cycle over.

Diplomacy is the reasonable one that will actually accept peace and ask for it. Warlike is standard TW unreasonable that will never surrender.