Going to war with other kingdoms and Empires

[Indianer]

It seems like most of the wars you can start involve taking a county or duchy at best. Is there any quick way to get more kingdom claims? Going to war with Kingdoms one county or duchy at a time is fine, but was hoping there might be a faster way to gain territory.

So far I have managed to build and Empire with England, Scotland, Ireland, parts of Norway, Sweden, Denmark, and West Slavia. Basically surrounding the Holy Roman Empire. But they are still larger than my British Empire, and I can't seem to pass them in size.

Was hoping to understand how I can grow faster, even if that means gaining more territory without war. If there are ways to vassalize de jour duuchies, that could help also.

[brownacs]

https://ck3.paradoxwikis.com/Casus_belli

You're looking for kingdom conquest wars and holy wars. The wiki has the conditions; they're largely cultural/religious. There's also the subjugate CB.

You can take realms without fighting yes but it's going to come down to either a lot of luck or a lot of manufactured 'luck' (murdering people). You're going to have to find realms with an heir (or ruler) you can marry and then get them married to your heir/ruler (with a marriage type that has children of your dynasty) so your child(ren) can inherit from both parents. The AI usually won't agree to this if the child stands to inherit anything, hence the murders. The AI also doesn't understand that heirs of heirs matter so that's another strategy you can use. This approach probably takes longer than conquering though, especially since they changed schemes.

Vassalising de jure duchies should be quite easy. There's an offer vassalage button and that shows you their acceptance score and the criteria for increasing it. It's things like their opinion of you, your title tier, whether you're de jure their liege or not, your powerful vassals' opinion scores, military strength etc. There's a diplomacy lifestyle perk in the left hand tree that increases it also. https://ck3.paradoxwikis.com/Interactions#Offer_Vassalage

[AceRattman]

you can buy claims from the pope if catholic. Invasions as tribal or clan. you can form a legend in order to get a kingdom tier claim and even refresh your one time only holy wars. you can do said holy wars.

there are a million ways to do it, just find one that fits whatever government you are playing