Lets say that this is Rome, Ad 198, and Septimius Severus is the Emperor. If anyone knows about him, then you know he doesn't play.
You are, through merit, nominated as a Caesar and are given commend of the Pannonian Legions, the best of the best, to move out the east to defend Nisibis (in modern day Turkey), a border city which the Parthians and later the Persians have coveted.
You make some obviously foolish decisions and Nisibis is razed: it's treasures plundered, the citizens led away to slavery, and the precious Legions were butchered to a man, their bodies found at the ground they defended.
Now your enemy has a foot hold on the border of your Empire. You hear rumors from refugees that the Parthians believe their god Ormuzd has given them back this city in preparation for the Final Judgement on the infidel to the west.
Emboldened by their victory, and with this new conquest, they have a proper staging ground for invasion. They are amassing a host larger than any known to man. Even the Sarmatians have made a pact, and many more Germanic tribes have thrown in as well for glory, plunder, and a chance at revenge against the Mistress of the Mediterranean.
You receive a emissary from Rome. Your Sovereign requires your presence to explain the events of Nisibis...
The point is that in real life if you were a Roman Magistrate, a dept. head for a corporation, or the night head shift manager at the janitorial agency, there would be consequences for your actions. You are held accountable for your decisions.
The janitorial service would fire you, the corporation may sue you or press charges on you, and the Romans, well let's just say that very few received the dignity of the "hot bath".
So what consequences are there for a host of 5th column agents within your ranks that are undermining your empire?
How is it in any way realistic for people to come and go in your faction, and basically set fire to your camps, without any reprisal?