Vassal Dukes becoming Vassal to another Kingdom

[Elmdor]

So I've ran into this 3 times now and I don't know why it's happening.

So I had a Duke vassal of my kingdom switch to becoming the vassal of another kingdom. There was no war fought or prompt on my part about any change.

I hold his De Jure kingdom title so I'm his rightful liege.

He still holds his Duchy title so he didn't give it away to his new king. There was no deaths involved with the duchy title ownership.

I can go to war, but I'd have to take all the land back piecemeal. Unless I luck out into a duchy fabrication. I can't interact with him in any way besides war.

Does anyone know why this keeps happening?

[Dizzy Ladybug]

what probably happened is that a vassal duke in another kingdom inherited the duchy in your kingdom. go to the duchy that you lost and check the title history. see if it was inherited by the vassal in the other kingdom.

[Elmdor]

Thanks for the idea, but I checked and there was no change in the owner of the title. It's still the same lord with the title.

[Dizzy Ladybug]

did that same lord inherit another duchy then ? they may have inherited another duchy in the other kingdom which switched their allegiance. it's kind of complicated.

as for getting the duchy back: A) you may want to see if you can invite a male claimant to your court who's claim you can push to take the duchy back all at once B) you can go down the middle learning tree to get the perk that allows you to buy claims to duchies and counties C) if you are catholic, you can see if you can request a claim to the pope.

if all else fails, you will eventually unlock tech in early medieval to go to war for de-jure duchies.

[Elmdor]

Ok so I loaded up the previous save to try and figure out what happens.

What I found is that this Duke inherits some Baronies when that King dies.
So this Duke is gaining land, but why does he join the other king? The land he gets still keeps him a Duke and I'm his King. Shouldn't he still be my vassal?

How does this system work? When your vassal inherits land they are supposed to stay your vassal as long as they don't become the same rank as you.

In this case I still outrank him so why does he go to someone else?

Thanks for the suggestions about reclaiming the land. I'm not too worried about it I'm just trying to understand what's happening.

[Dizzy Ladybug]

yes, to be honest, I don't fully understand it myself despite playing the game for so long. i can only theorise as to why this sometimes happens.

another thought i had was that the other kingdom had High Crown authority, which may have prevented those baronies from leaving their kingdom and potentially taking your duke when they inherited those new counties.

and on that note, you should also try to have High Crown authority to prevent your vassal's titles from leaving your realm.

[Elmdor]

Yeah it does seem weird. I'll have to look around more and see if there's more information about it.

Thanks for the tips. I have higher authority on my list to do, but I'm trying to finish some other war based ones first. I'll have to move it higher on my list.

[Buadh]

Hi, just seen your conversation and sounds interesting. Thought i might add an idea i had when reading. is it possible that your former duke had a title allegiance to the other king? if that king has an elective succession law then maybe that duke is bound to allegiance with that kingdom rather than yours? not entirely sure but i know title allegiance can be something tricky

[Elmdor]

Originally posted by Buadh:

Hi, just seen your conversation and sounds interesting. Thought i might add an idea i had when reading. is it possible that your former duke had a title allegiance to the other king? if that king has an elective succession law then maybe that duke is bound to allegiance with that kingdom rather than yours? not entirely sure but i know title allegiance can be something tricky

I checked it was just a Confederate Partition succession law.

I'll have to investigate more next time it happens. Maybe the game just defaults to your new holdings De Jure liege.

[The Former]

The only time I've seen this happen since the update, it was a case of a kingdom title going to an earl. No lands, just a title. Because the kingdom title was under a foreign empire, and was higher than his earl title, he became a vassal of the empire. We're totally sure no shenanigans like that went on?

[Elmdor]

Originally posted by Lockfågel, Paradoxriddaren:

The only time I've seen this happen since the update, it was a case of a kingdom title going to an earl. No lands, just a title. Because the kingdom title was under a foreign empire, and was higher than his earl title, he became a vassal of the empire. We're totally sure no shenanigans like that went on?

I'm pretty sure, but just to paint the whole picture for you.

I'm king of Brittany and Aquataine with the duke in question being the Duke of Brittany. This Duke was 2nd in line for titles in the kingdom of Slovenia. He wasn't directly related to the king, but the king only had 1 son. Slovenia had a confederate partition succession and the king died. The main heir got the kingdom and duchy title and my vassal duke ended up with 2 of the baronies. This is when my duke switched to his allegiance to the new king of Slovenia taking the whole dutchy of Brittany with him.

As a side note the duke was actually part of my dynasty, but in a cadet branch. Not that this should effect anything as far as I'm aware.

If there's any other details you think might be relevant let me know and I can dig it up.

Also on a positive note this turned out not being as bad as it could have been. All these people eventually died and the dutchy of Brittany ended up with a newly generated independent ruler who I was able to vassalize.