Quick Links
The Commonwealth is a major Eastern European power in Europa Universalis 4. Historically a union of Poland and Lithuania, it can be formed by either of those nations as long as the correct prerequisites are met. Doing so allows players to unify the region and present a united front against the powerful rivals surrounding them.
Poland generally has a much easier time forming the Commonwealth, but doing so as Lithuania allows different National Ideas as well as a unique Achievement, "The Uncommonwealth." Regardless of your starting nation, here's everything you need to know about forming the Land of Golden Liberty!
How To Form The Commonwealth As Poland
Poland starts the game with no ruler, as their previous king was killed in battle against the Ottomans. Very early on, Poland receives an event that allows them to either elect the Grand Duke of Lithuania to the throne or choose a Polish noble in hopes of getting a ruler with better stats. Electing the Grand Duke grants Poland a Personal Union over Lithuania, effectively making your eastern neighbor a powerful vassal.
While it's possible to integrate Lithuania after the Union has been in place for several decades, it's in Poland's interest to keep the two countries separate until around 1530. During that time, do whatever it takes to maintain Lithuania's loyalty; usually, it's enough to simply keep a diplomat improving relations with them, but the occasional monetary gift doesn't hurt either!
Once Poland has reached Administrative Technology level ten (which usually happens in the mid-1500s), the decision to form the Commonwealth will be unlocked. To take the decision, Poland's Stability must be above zero, and Lithuania must have fifty-eight or fewer provinces total while still being a junior partner in the Union.
Poland must also own Warsaw, Krakow, Marienburg, and Danzig as cores, so be sure to annex the Teutonic Order while you're waiting for the necessary tech level. It's best to declare the Order as your rival as soon as the game begins and conquer Danzig quickly, as they will sometimes sell the province to Brandenburg. If that happens, it will be a lot harder for Poland to take Danzig since it will have fallen within the Holy Roman Empire.
How To Form The Commonwealth As Lithuania
To form the Commonwealth as Lithuania, you'll need to refuse the Personal Union with Poland when it's offered, usually within the first two years of the game's start. Doing so grants Poland a powerful monarch from the local nobility and removes your positive relationship modifiers with them, but lets you maintain your independence. Once you've stabilized your economy and built up your military, you can set about enforcing a union on your terms!
Lithuania starts the game with a small but dangerous budget deficit of about two ducats a month. Your first task should be balancing the books; start by using the Grand Duke's decent Administrative and Diplomatic skills to develop key provinces. Vilnius and Kiev are good cities for Administrative development, while Ula, Polotsk, and Sluck have decent trade goods that can be enhanced with Diplomatic development.
Lithuania starts with a merchant assigned to the Baltic Sea - move him to Kiev as soon as the game begins to get much more use out of him.
While you're getting your economy in order, look for alliances with Poland's rivals. This might not be feasible until you've refused the union, but you'll need the extra help when the time comes to go to war. Be sure to have at least one ally capable of countering Muscovy as well; the Grand Prince will be looking your way eventually, so it pays to be ready!
The majority of Lithuania's provinces are Orthodox, but your state religion is Catholicism - this isn't a problem thanks to Lithuania's tolerance bonuses, so you don't need to spend time and money on missionaries at this stage.
If the opportunity arises, conquering East Prussia is a great way to expand your economic base. The gems at Konigsburg are especially helpful, though you may need to cede some land to the Estates for enough Governing Capacity to make the area into a state.
Once your army reaches ninety percent of your Force Limit, you'll be able to complete the mission The Polish Succession. This gives you a casus belli to enforce a Personal Union over Poland. It needs to be used within twenty-five years, or else it will expire.
After winning the war and forcing the union, maintain your status as a senior partner until you reach Administrative Technology level ten. During that time, slowly take provinces from Poland until they have thirty-one or fewer.
Once you've reached the requisite tech level, make sure your Stability is maxed out and that you control the provinces of Vilnius, Kiev, Turov, and Minsk. If you meet all the requirements, you can form the Commonwealth.
How To Form The Commonwealth Without A Personal Union
If neither country can enforce a union over the other, you can still form the Commonwealth through military means. Poland or Lithuania can unite the region as long as they are not at war, have reached Administrative Technology level ten, have maximum Stability and control all the requisite provinces for both countries as cores;
- Warsaw
- Krakow
- Danzig
- Marienburg
- Vilnius
- Kiev
- Turov
- Minsk
While this is the hardest route to the Commonwealth, the outcome is the same; in all three cases, you'll receive a Prestige bonus, permanent claims on the area, acceptance of the other country's culture, and a free tax boost in one of your provinces.