I vassalized what was left of Prussia. Unfortunately, they have over 400 development, it seems impossible to annex them. Do I have to release them and conquer them again?
Yeah, overfeeding vassals ain't a good idea. My 1000 dev Flanders is only kept in check with constant placation and province feed.
Did you force vassalize a nation with 400 development?
You could use an exploit by march him and revoke it. It magically remove the liberty desire from getting province via rebels. It's worth the stab hit.I had the same problem as Ottomans. Released Persia from one province taken from QQ, forget the name but just south of Tabriz. Then Timurids collapsed to Persian rebels and my vassal suddenly had over 300 development (this was in the 1460s). Had opinion +215 but liberty desire still a flat 100% (from events).
Still have the game but haven't continued. I've no idea how to annex from there, especially as I play without any DLCs.
You could use an exploit by march him and revoke it. It magically remove the liberty desire from getting province via rebels. It's worth the stab hit.
I vassalized what was left of Prussia. Unfortunately, they have over 400 development, it seems impossible to annex them. Do I have to release them and conquer them again?
Declare war on #2 and white peace as soon as possible. They cant support your vassal if you have a truce. After that spend some prestige to get your vassals liberty desire down.This wasn't a case of overfeeding, they haven't gained a province since I took them. I had
been taking stuff fast enough that I was having a hard time keeping up on the coring, I figured I would use some diplo points instead--but the lowest liberty desire I've seen is 89%. Now that the #2 in the world has decided to support them their liberty desire has been pegged at 100%. (I'm #1 but I'm having to be careful about coalitions--most of the rest of the world would like to gang up on me if I were to show weakness.)
Kick the supporter in the face. The vassal will not rebel while you're at war because of some code quirk. This should both remove the support and give you some prestige.
Then drop your prestige into appeasing your vassal's butthead of a ruler and start annexing ASAP. Develop them a little if you need even more reduction for whatever reason. Keep a diplomat locking their opinion of you at cap too, that affects LD.