My late father-in-law and myself were civilian employees for the Air Force both at the same base. He once told me that you practically have to commit murder to be fired from there. In a nearly thirty year career, I can say that the gap between the number of employees that needed firing and the number I knew that were fired is a big one.
My dad was in the army long before I was born. He used to say government workers were like missiles; you couldn't fire them and they hardly ever worked. Of course he would use that for state and federal employees interchangeably.