Well, they gave it a good shot.
But they were never able to protect Europe because they have been conquered all the time dating back to the Romans and before that.
The Barbarians in the middle ages overrun them as well. Same with the Ottoman empire and the Soviets they have always been conquered by them.
The German tribes were the once defending Europe.
Also, let's be honest here they would be so much better of if they would have been Germanized in the past.
There is no point for them to govern themselves. Because they will never ever amount to anything.