Let’s see … I believe I promised you some Poles, ya?
First we have Jan Zenowicz.
I did find a Jan Zenowicz who was castellan of Smolensk, but he died in 1614 and the game begins in 1655, so … perhaps he’s a vampyre?
Next we have Stefan Czarniecki.
Now, unlike Zenowicz, this dude is so important that he is mentioned in the Polish national anthem, so … yeah. He was captured in the Battle of Jovti Vhody, the opening battle of the Khmelnytsky Uprising, was a defender in the 7-month siege of Kudak Fortress, and was part of the huge Battle of Berestechko. His fame really grew after the Khmelnytsky Uprising, though.
Finally, young Michal Vishnevetsky (Wisniowiecki).
He is not really mentioned in the book, in which his father Jeremi is a major character. This makes sense though since he was born in 1640. He is seen in at least one scene of the movie, in which he would be .. 8? 9? .. in this adorable miniature hussar armor. (I just spent a good 45 minutes searching the web but not finding a pic of this .. sadface) Anyway … in the game he would be 15 when it starts. In reality he was away at school, studying in various places until 1663. But this isn’t reality, so the future king finds himself on the battlefield.