Quote Originally Posted by Franconicus
Here are some German:

Moltke (the nephew): He soiled the Schleiffen plan completely.
Falkenberg: His Verdun plan was as stupid as can be.
Paulus: Did not havethe courage to withdraw his troops from Stalingrad

Roman: Varus, of course!

But what about single mistakes
Well Von Paulus would have been removed from command and shot if he had tried to pull his troops back. It was Hitler's bungle not the general who carried out the idiotic orders. To be a bad commander you need to at least have been able to choose some other course.