Polish-Lithuanian Commonwealth

The Polish–Lithuanian Commonwealth was a bi-confederal Eastern European state comprised of the Kingdom of Poland and the Grand Duchy of Lithuania, who were both ruled by one monarch. At one time, the Commonwealth was among the largest countries in Europe. Polish and Latin served as the official languages of the Commonwealth, and Catholicism was the state religion, though other religious groups existed as well.

On July 1, 1569, the Union of Lublin was signed. Ever since the Krewo Agreement and the marriage of Queen Jadwiga of Poland and Grand Duke Władysław II Jagiełło, Poland and Lithuania had been close allies; now, they levelled up. Their descendant, Sigismund II Augustus, who turned out to be the last ruler from the Jagiellonian dynasty, eventually ruled as the Commonwealth's first King of Poland and Grand Duke of Lithuania.

The Commonwealth operated under Golden Liberty, which was sorta like modern democracy. The Warsaw Confederation maintained religious and ethnic pluralism, though that wasn't always the case.

The Commonwealth would meet its demise in 1795, though shortly before, the Great Sejm wrote the Constitution of 3 May 1791, the world's second constitution.