feudalism. In Poul and Karen Anderson's King of Ys Tetralogy, the ex-king must organize military defense after the withdrawal of the Roman Empire. In fact, he helps to initiate the feudalism that is exported in The High Crusade. In Poul Anderson's History of Technic Civilization, planets pay tribute and receive protection from the Terran Empire.
In SM Stirling's Dies The Fire (New York, 2005), Mike "Lord Bear" Havel must organize society and defense and apportion land without money as a means of exchange. When he has outlined his plans, it is suggested that he call the land grants fiefs and the apprentices pages...
He is told:
"'...yeah, Boss. Something a little like it has happened before.'" (p. 559)
"Boss" was the title adopted by Mark Twain's Connecticut Yankee.