I'm one of the "eternal wars" players or you get peace with 1 but then 1 or 2 others declare war.
The problem imo is related to a few things :
*Power rating of the kingdome. Roughly each time I hit 10-12k this problem arise.
Basically since the starting factions power rating is what 4-5k roughly, it means you've gobbled up large chunks of either 1 kingdome(usually not) but large parts of 2-3 of them.
The AI puts too much emphasis on the power, and not accounting for how many actual lords there is and how much of said power they can use to muster armies.
Meaning most of that power is actually in settlements and not out and about, in that regard the factions actual power is equal to the others(generally its less, as the AI is better at recruiting more mercnaries).
*Mercenaries they actually are part of the problem, I did a test where I just removed them from the game, and then the game unfolded with normal peace/war more or less all the time.
The problem is that instead of admitting defeat, and paying tribute - kingdomes just keep on hireing mercenaries.
Specially when you come to that powerpoint I mentioned, then the AI in proximity to you will stop fighting amongs themselves and gank up on the player faction.
This is more so an issue when you are locked in a 1v1 with them, then you'll see them have 2-3 merc companies shy from haveing all of them in their employee.
Solution - limit the amount of companies a company can hire, maybe 3-5 tops(thats 3*4 lords more for them or 5*4 so thats kind of alot of parties/troop to bolster them).
This would also mean that the kingdomes should be more inclined to accept peace instead of dragging on a war that "never end".
*Lower threshold to want peace when more lords are imprisoned - when I have captured 30+ of the other sides lords and they still dont want peace it dont feel right(again this is also sort of caused by mercenary bolstering them too much).
Prolly cap it at 15-25 and they should want peace, that many lords would be about 1-2 fairly big armies on their own, and if that many had been defeated well, they usually want to have peace to regroup.
The issue is more frequent I think to certain playerstyle, where we are "in the thick of it" all the time, instead of just be *meh you lot can burn*
So the kingdome "wins" too much and thus see no need to stop, dial down the warmongering lust, add more fatigue/exhaustion from war.
*Bring back from Warband peace duration and tribute aswell.
Tribute, cause well then they arent "forced" to declare war, cause they feel they pay to much tribute now vs what was needed.
Peace duration, cause after decimating an army after army, and getting them to submit..
2 days later guess who declares war again - they are all out of the dungeon, have gathered up all the parties again, and we got a war declaration from another kingdome.
Too put it this way, when this "chain of endless war started" my oldest kid was 4 yrs old and had 1 sibling.
He is now 14, and have 5 more siblings.
10 yrs + of endless/chain wars.
Just tanks the fun out of the game.
Started with Battania, we conqured alot of their lands, after they had a long war with Vlandia(I'm Sturgia).
In the midst of this Khuzait on the opposite of the map declared war, I went there, crushed ther armies hard - Khuzait got declared war upon by Norther Empire - > peace with Khuzait.
Battania still at war with us.
Now Vlandia declares war on us, which leads to us conquering the lands they had taken from Battania.
Battania then declares war on Vlandia. Vlandia now wants peace with us, we're still at war with Battnia.
Western Empire declares war on us(one of the holdings we took from Vlandia was Lageta which they had taken from WE)(Fair enough).
We have peace with Battania now.
Western Empire war drags on and on and on and on back and forth.
Vlandia declares war, 2-3 big battles with them, Battania declares war on Vlandia - peace with Vlandia, still in war with WE.
Battania declares war on us(while still at war with Vlandia, that they are looseing..).
WE accepts peace.
We take more of Battania, Vlandia declares war on us.
We get peace with Battania, but still at war with Vlandia.
I dont want there to be peace all the time once you hit that threshold, but ffs(pardon my french) atleast some time in between.
Once you hit that threshold you got 2 choices either let it all burn and loose all progress so to speak in days, or be locked in the cycle of endless wars.
Now if this is how its intended to be designed, then this is not a design I think is good.
Tbh this is one of the issues which makes me want to stop playing the game without mods, as it just tanks the fun.
Also to some degree it undermines the need for "legacy play" as within 1st characters death you have conqured the whole map, cause the other side never ever wants to submit.
Ideally it would rather have unfolded with some peace, and that the others reclaim a few of their lands again, then peace. we take it back etc.
Not cause we're so sucessfull it will jsut never end - warmongering.
I know its wall of text, ranty, but its sadly how I experience the game and for my playstyle it tanks the fun once you hit that lvl.