German 20 Mark 1914 with occupation stamp

Hello,

I am reaching out to you with this 20 Mark German occupation banknote from 1914.

I am having difficulty identifying it and determining its origin.

Does anyone recognize this stamp or know what the initials CD in the center stand for?

The circular legend reads: BILLETS DES VILLES ENVAHIES.
At the bottom, I believe I can make out PO between two stars.

There is a strong possibility that the stamp is Belgian or French.

Any information would be greatly appreciated, and I thank you in advance for your help.

Sam

I am not sure about  the stamp but I believe this is the Numista page for the banknote.

N#206187