There are no Polish units, there are only units from the 8 major powers.
If the territory was contested (both Central Powers and Allied troops occupy the territory) at the beginning of your turn, then, yes, you are not required to attack.
This is important because you may not have enough units to attack but an allied power might be able to reinforce your troops before your opponents turn, giving you enough units to defend.
@oztea:
So let me see if I understand this correctly.
Lets say Germany attacks Poland. 8inf vs 4inf.
Germany gets 2 hits. Russia gets two hits.
Now on Russias turn, those polish units don’t have to roll any dice if they don’t want to right?
They can just sit?
And on Germanys turn their units can just sit if you want.them to?
How do you keep track of this during your turn?