With the 1.26 Paradox introduced the endgametags so you cant form another country after you formed the commonwealth, this way to from prussia is no longer possible.

With the next patch PDX will add the option to remove endgametags, making this strat possible again.

First of all we need to know what is necessary to form Prussia:

- Pomerian, Saxon or Prussian as primary culture
- no monastic order
- admintech 10
- not at war, no subject and no nomad nation
- is protestant or reformed
- owns cores: Königsberg, Warmia and Danzig


Normally you would choose Brandenburg or the Teutonic Order.

















"But Polands primary culture is Polish!"


culture shift is the answer

At the start with Poland you have one vassal, Mazovia, Moldau as a March, and later you get Lithuania in a PU.

You should do the classic Poland opening by farbricate claims against the Teutonic Order, choosing the right rivals for you, wait for getting the PU over Lithuania and then you choose one ally with your last diplomatic slot (it is crucial, that you dont go over your diplomatic slots, because you will need lot of diplomatic points)
Ally Brandenburg, Bohemia or Austria.

With your claims finished attack the Teutonic order asap; in the best case the Teutons Allys are the Livonian Order and Riga.
You will win this war with ease, so take Riga and as many provinces you can get from the Teutons.

Hire a expensive diplomat or focus on diplomatic points;
Then start culture shifting the northern polish provinces from Polish to Prussian.

Remove the march from Moldau when you can manage the -1 stability hit.

And then play then play like you would play Poland normally, conquer the rest of Nowgrod, stopping Ottoman Blobman from getting further into europe, fight the hords and try to feed rasjan and odjonew to Lithuania, so Muscovy cant form Russia.

When your truce is over, attack the Order again and fully annex them. Afterwards take a look how much percent the prussian culture has from the total development; if it is still under 50%, then convert a couple of Polish provinces to Prussian again.

As your first idea i would recommend getting the religious ideas; because taking a military idea first, is normally a bad choice and you dont have tons of diplopoints.
religious gives you always a CB against the Ottoman Blobmans, the Hordes and the evil Russia.
+ you dont need diplopoints for peace treatys with the "DEUS VULT" CB; perfect for expanding to
anatolia and to the east in the early game.


When the Prussians have over 50% of your total development, then turn them into your primary culture.
Start integrating Mazovia and Moldau after the culture shift, for freeing you diplomatic slots, so you can get additional allys.

Around the mid 1460s Prussian will be your main culture.

Then continue playing as the usual Poland.

As soons as the Reformation triggers; pause and convert to Protestant, usually your PU-subjects will hate you for this, but not Lithuania, because they are your historical friend; but dont forget to improve your relations with them, just in case something could go wrong.

I recommed to convert to Protestant, before forming the commonwealth, because it is easier to prevent the religious turmoil, when your country is smaller.

(Do not convert all orthodoxs to catholic after the 70s, because they will have religious enthusiasm, and enthusiasmic catholics are impossible to convert. Not what you want during the Reformation in your country, when you finished to convert and your country is stable again, form the Commonwealth.
Admintech 10 is normally reached shortly after the Reformation.

When you formed the Commenwealth, you integrate Lithuania with this decision.
(DONT FORM PRUSSIA BEFORE FORMING THE COMMONWEALTH)

With Lithuania, your integrated vassals and your conquest you should have easily over 600 development.

Then form Prussia and take the Prussian ideas.