What had prevented Germany from uniting prior to the mid 1800's?

The Holy Roman Empire prevented Germany from unifying, due to the defenders of the Holy Roman Empire (Catholic defenders) in the mid 1800's

Explanation:

I believe that Germany did not unify with Germany until mid-1800 (Prussia being the main state) as I think the French did fear the unification of Germany and wanted to avoid the unification at all costs. I also do believe that traditions were different between them but were forced to unite after the treaty signed in Versailles taking Alscae Lorraine.

ok whats to talk about were you scared or what?