The Destroyers

The Destroyers is a science fiction novella by Randall Garrett first published in 1959.

Any war is made up of a horde of personal tragedies--but the greater picture is the tragedy of the death of a way of life. For a way of life--good, bad, or indifferent--exists because it is dearly loved...

Xedii, an agrarian, feudal planet is attacked by a technologically advanced planet, which offers the inhabitants of Xedii 'freedom'--a word the farmers of Xedii don't know and can't understand when it's explained to them.