That concept held true for the Swedes and Swiss in WW2 (Hitler feared invading them would cost him too many casualties - a remarkable thought when one considers that Hitler invaded the Soviet Union after it had purged its officers).
Likewise, it held true during the Civil Rights movement here in America. Rural America has always been armed. Selma, Alabama is in the rural heart of the "Black Belt" of the South. Even the corrupt police officers who attacked Blacks at the Edmund Pettus Bridge on their march from Selma to Montgomery knew better than to pull a gun. Had they shot the marchers, rural Alabama would have become an armed, enraged adversary.
So instead of shootings, there were dogs, firehoses (in Birmingham, anyway), and billy-clubs.
But had Blacks NOT been armed, it's pretty clear what the Klan would have done.
In contrast, the Klan today is toothless and ridiculed. History has left it behind.
For this, we can thank the 2nd Amendment.
Pretty much a universal truth.
Just a correction.
Thanks for posting it.