Mandatory declaration of war against Belgium?

[sansing]

Is it possible to not declare war on Belgium, fighting a defensive war in the west and trying to defeat Russia first?

[Robotron]

In the original game:
NO. The game script calls for an automatic German declaration of war against Belgium on turn 3.

In Potzblitz mod:
YES. You are free to attack Belgium or not when playing Central Powers. Not attacking Belgium will delay Britain joining the Entente unless the German navy starts bombarding French coastal cities or France is losing too much ground to Germany. There are also alternate war plans for a German attack through Switzerland and an all-out German attack on Russia.