New sudden kingdom within my territory

[innan gryningen]

Hello, lads! I was wondering if anyone could explain me the following game mechanics I met during my last game: I started for Genova under the Kingdom of Italy that was conquered by the West Frankish Kingdom and then by the Byzantium. Under basileus I captured almost all lands that belongs de jure to the Kingdom of Italy (the very title was in hands of the basileus by the time) and usurped the Kingdom of Romagna. I was the largest vassal with the most developed territory at the moment. But all of a sudden an independent Kingdom of Italy emerged within my territory. It had half of my lands including the capital and my domains. After that I faced a civil war waged by a liberty faction which has nothing to do with the new Kingdom of Italy but caused me headache. However during the civil war I received notifications that the king of Italy took over some of my titles including my new capital without declaring war or anything. So I ended up cracking down on my vassals having just a few and most undeveloped lands. I had no populist or independence party within my kingdom, the new ruler of Italy was a noname with no claims and dynastic marriages. I was told that there could be a populist faction challenging my suzerain but that does not explain first why I lost these very lands, second why Italy was independent and how the hell he managed to take over my lands with no claims, war etc. afterwards.
At the time of these events catholics participated in a crusade and the suzerain was challenged by a claimant faction. Maybe it could have an influence but...

[Cola]

It's possible to create a new title when certain conditions are met (ie. controlling half of it's de jure counties). The other nobles will do so if given the opportunity.
If I'm correct this may even cause them to become independent, if they create a title that is the same tier as your primary title.
So if you are a king, and one of your dukes controls enough counties to create a kingdom, he may become independent. But I may be mistaken about that, I think I read this in a tooltip.

[corisai]

Originally posted by Cola:

So if you are a king, and one of your dukes controls enough counties to create a kingdom, he may become independent.

Yes.

[CrUsHeR]

Originally posted by corisai:

Originally posted by Cola:

So if you are a king, and one of your dukes controls enough counties to create a kingdom, he may become independent.

Yes.

Wrong, you can never usurp or create titles of the same rank as your liege.

Only way around this is the Subjugate CB, where your vassal may steal a foreign title of your (or higher) rank. This makes him independent.
And of course they may inherit or claim a kingdom.

Both cases require the title to already exist, though.

[innan gryningen]

Originally posted by CrUsHeR:

Originally posted by corisai:

Yes.

Wrong, you can never usurp or create titles of the same rank as your liege.

Only way around this is the Subjugate CB, where your vassal may steal a foreign title of your (or higher) rank. This makes him independent.
And of course they may inherit or claim a kingdom.

Both cases require the title to already exist, though.

Disagree. Being under Byzantium I myself usurped the title of the Kingdom of Romagna so I became the king but remained within the Byzantine Empire so far.

And as for the powerful vassals, yes, it can happen if this vassal controls 2/3 of your kingdom title territory and strong enough or he has a claim over it but it will happen throughout the war in support for a claimant or independence or if you agree to an ultimatum delivered to you by an opposition.

It is most likely connected to an Italian populist faction challenging my suzerain (I will check it later) but it gives no answer about why it emerged from within my own territory. OK, let's say there were the populists and they won (I haven't had noticed any declaration of war, though, but I suspect there could be an ultimatum my suzerain foolishly agreed to) but can my suzerain hand over lands that he doesn't own himself? What I'm saying is that it's more reasonably that these populists must've carried out their fishy dealings within my kingdom anyway.

Moreover, it doesn't explain why I lost a part of my remaining lands just by a couple of notifications afterwards.
I suggested first he usurped titles of mine but he had no money and the usurpation of title doesn't involve taking over lands that belongs de jure to this title automatically to the owner of the title.

And finally if it can actually happen how to avoid this bloody event? I coloured all my territories into Italian culture and Catholicism to prevent any unplanned uprising amongst other reasons. Yet I saw my kingdom falling apart to never be able to fight back:(

[CrUsHeR]

You can usurp titles of other vassals, but not of your liege. And likewise you cannot create titles of the same tier as your liege.

Here are the two error messages you get.

Left - trying to create the Kingdom of Kimek as a Duke vassal of Cumania 1066
Right - trying to usurp your liege's kingdom title

https://steamcommunity.com/sharedfiles/filedetails/?id=2263887109

https://ck3.paradoxwikis.com/Titles#Usurpation

"If a character is a Vassal, they cannot Usurp a title belonging to the Liege, nor can they Usurp one that has the same Rank or higher than the Liege's Primary title."

And factions with claimant installation have absolutely zero to do with the title usurpation or creation mechanic. These are a faction demand which is resolved in an ultimatum or a revolt. Usurpation is when you steal the title of a foreign ruler where he can do nothing about it.

[Cola]

Good to know!
Then I'm genuinely curious what happened in OP's case; what could cause a new kingdom to arise inside an existing kingdom without a war?.

[UnCivilServant]

Originally posted by Cola:

Good to know!
Then I'm genuinely curious what happened in OP's case; what could cause a new kingdom to arise inside an existing kingdom without a war?.

Sounds like an independence faction against the emperor and the emperor just granted their demand.

[innan gryningen]

Originally posted by CrUsHeR:

You can usurp titles of other vassals, but not of your liege. And likewise you cannot create titles of the same tier as your liege.

Indeed. The mechanics of succession and claims are well-known. I was not talking about an usurpation of my suzerain's title, cause' the game stands against it.

Again, I hardly can explain not the very fact that the new kingdom emerged from within my territory which is quite upsetting but c'est la vie (I'm getting more convinced this has something to do with the populist party against my suzerain), but the fact that the newly appointed king somehow took over my remaining titles with lands including my new capital without declaring war or having any formal claims over them.

[innan gryningen]

Originally posted by UnCivilServant:

Originally posted by Cola:

Good to know!
Then I'm genuinely curious what happened in OP's case; what could cause a new kingdom to arise inside an existing kingdom without a war?.

Sounds like an independence faction against the emperor and the emperor just granted their demand.

There was no faction for the independence of the Kingdom of Italy. In fact, the only one who could make it was me.

[UnCivilServant]

If the populists you mention above were granted independence, you would seize the titles for which they had enough counties.

[innan gryningen]

Originally posted by UnCivilServant:

If the populists you mention above were granted independence, you would seize the titles for which they had enough counties.

Maybe. It's the only explanation I can get. I think populists often look at religion and culture of a suzerain, not vassal's, so they uprise against him paying no regard for my own situation. We could only love this game for its turn-ups, indeed.