How does it work? It’s quite simple. At any point during a campaign (although it’s best if you do it once the campaign has been completed) you’ll be able to select the button Export core from your campaign -> Core army screen. You can then save your Core army.
At that point, start the next campaign. You’ll be prompted with this screen, asking if you intend to import a Core army.
Click yes, and you’ll be able to select which one you’d like to import.
Select the one you want to use, and there you go! Now you’ll start with a set of units carried over from your previous campaign. They are not free, though! You still have to buy them like you’d buy a new unit, but they retain the name and 30% of the experience they had, as if they had been destroyed. That is, naturally, for balance purposes.
That would be all regarding the Import tool, but there’s something else we’d like to show you today. Players who own the Winter War DLC will have access to a unique division in Blitzkrieg, after they research the Waffen SS specialization: I’m talking of the SS Wiking division, a completely unique division unlike any other in the Wehrmacht.