Not only are the separatist forces, Chaos believers, and Alien enemies difficult to fight; on the contrary, when the Empire is willing to spend money, these things cannot withstand the edge of the Empire's army.
But the problem lies in the management afterward.
If you can't issue the Extinction Order all at once, then why bother taking it back?
A large amount of Imperial Army is thus entangled in security battles, costing quite a bit.
What's more terrifying is that this place seems to have some special atmosphere. Many troops suppressing the rebellion, after a few years, tend to become separatist forces themselves.
The armies dispatched from the Central Empire might be slightly better, but the Star Realm Army, which is not directly from the central core, is not as reliable.
