How to best break up a friendly ally?

[TeeWee]

I'm a Musvowy that has just formed Russia (1540'ish). Ryazan has survived and has been a good ally (not a vassal) since the beginning. And it's becoming too big to simply vassalize and absorb through diplo means I'm afraid.

History: Lithuania remained independent and I've snagged Poland as my ally. I've managed to vassalize the Livonian (Orthodox) Order and grab bits of Lithuania, while Ryazan grabbed Ukranian parts of Lithuania. On the southern part, I grabbed Kazan, while Ryazan grabbed most of the Golden Horde.

Now, how do I go forward with respect to Ryazan? It's blocking my way to the Black sea. I can still go south and east, as well as kill of the rest of Lithuania, but I actually want the Crimea.

EDIT: Vanilla, Base game only, latest update on Steam.

 

[Grubnessul]

Break the alliance, insult them, declare them a rival and start building a spy network

 

[True_Heir_of_Rome]

What he said^

Another more "Scummy" tactic (that is better used on a larger ally) is to wait for them to call you into a war, then dishonor the call. The alliance breaks, they spend the next few years getting wrecked, you pick up the pieces in 5 years when the truce is over. This was how I used up, then beat France as pretty much any nation for the longest time. It's worth the prestige and loss of diplo rep if you can work it right.

 

[qwertzuiop]

The best possible way is to attack one of their allies if they have any and then call them in as a co-belligerent.

 

[Gnostek]

I'm pretty sure you can't call your allies as cobeligerents from the other side

 

[bbqftw]

The best possible way is to attack one of their allies if they have any and then call them in as a co-belligerent.

correct answer. Its even better if the rest of your actual targets allies are also allied to you, so you call them as well.

Now your target had 2+ alliance slots consumed by people who are now at war with them.

 

[bbqftw]

I'm pretty sure you can't call your allies as cobeligerents from the other side

you can. Its an extremely powerful 'feature'

..

 

[Vetgirig]

Another more cheesy way is to go to war and then offer your allies provinces in the peace deal when you NOT win the war. (somehow your armies was busy taking care of other business on the other side on your country)

Make sure the enemy war leader wants your allies provinces before going to war.

 

[TeeWee]

Thank you for your suggestions. I'm going to see how far this gets me. This is how my southern and western borders look. Livonian order is a vassal, ready to be absorbed. Kazan is also my vassal, but still angry at me for force vassalizing.

You can see how I let Ryazan get a bit out of control. At first I was nurturing her to potentially vassalize, but that never materialized, but they were a valuable ally versus Lithuania, drawing sieges and battles away from me. But she is rather aggressive and is an opportunistic ally, eating the Golden Horde and Crimea... Well, now that I have staked my claim over the entire territory of Russia, she will have to learn her place

I don't think that Ryazan is a valid rival target (Mamluk, Denmark and Austria) but will see how that plays out.