Slitherine

Ok, I just want to make sure I have things right. There is only one campaign for this game -- Poland is the beginning of it, but the other 3 campaigns just start LATER ON in the SAME campaign, right??

Not necessarily. For instance, if you play the '43 West campaign, you'll never get to the US. The campaign that starts in Poland is just the longest path available. Here's the campaign path from the Library (doesn't show the whole thing because of the scroll bar; go the Library to see it all).