Claire Wolfe recommended The Moon Is Down a few days ago. It's a Steinbeck novelette set in a small town in Northern Europe starting on the day the conqueror's troops take control.
It's well-written propaganda from 1942 -- as approved by Wild Bill Donovan!* -- but it could be set in many places and many times. About any point in history -- trade the rifles and pistols for spears and short swords, and the troops could be from Rome or Babylon.
While not (I hope!) directly analogous to current events, it certainly contains a valuable lesson, one I hope the Great White Fathers in Washington D.C. are capable of grasping.
* Strange but true.
STANCOR 10P TRANSMITTER: UPDATE 12
4 days ago