"The Specter General" is a science fiction short story by American writer Theodore Cogswell, his first published work.
The 427th Light Maintenance Battalion of the Imperial Space Marines is sent to an uninhabited planet to set up a base, but is forgotten when the Empire collapses in civil wars.
Periodic visits by the Inspector General (actually the battalion commander hidden in a still-working "battle suit") maintains the fiction that there is still a functional Empire.
A ramshackle Galactic Protectorate eventually emerges from the rubble of the Empire, though incessant power struggles keep it weak.
Conrad Krogson, head of War Base Three, takes his fleet out to search star systems that have not been visited in living memory.