Congress Polandball was a Russian Empireball's puppet.
In 1807, Saxony, Poland-Lituaniaball's friend, founded a state called the Duchy of Warsaw under the reign of Frederick Augustus I. After Napoleon's defeat in 1815,with the effects of the Congress of Vienna, Europe was re-drawn and Polandball became Russian Empireball's puppet state, although it would be more appropriate to consider the two in a personal union, as the emperor of Russian Empireball was the King of Poland as well.
Despite having a separate government and Constitution, he was dissatisfied with the outcome and rebelled. Around this time a certain Belgiumball was rebelling against Netherlandsball and succeeded. Unlike him, however, he failed and Russian Empireball took away his Constitution, Sejm, and army. He rebelled again in 1863, and although it was more successful, it failed and Russian Empireball punished him even more, eventually to the point of becoming a mere province (Vistula Land).
During World War I, with the promise of independence, Congress Polandball joined the war against German Empireball (who was then Prussiaball ) and Austria-Hungaryball, who also had some Poles fighting on their side. When Warsaw was captured, Congress Poland was replaced by a puppet Kingdom of Polandball (1916-1918) to better manage it against Russia. After the war Polandball gained independence as simply Polandball.