A town of 12,000, like the one in the story, can have serious problems when faced with a violent gang of just a few dozen young men. Even big cities can be effectively be controlled by mafias who represent a fraction of one percent of the population.
Out of the 4,500 immigrants dropped into this small town, they should be able to organize hundreds willing to kill. Out of the 12,000 townspeople, the military age males are probably just about the same number as those among the immigrants (~3,000 each). A few stabbing deaths will intimidate many - and there is already extensive intimidation occurring.
Only about one in two thousand Americans ever kills anyone in their life, and I’d guess that it has been significantly fewer in Germany. Times change though.
The generation that got the most patriotic education is dying off—those who were children during and shortly after the Second World War. Children absorb things to the bone. And look what’s been happening to them for decades?
I only hope that homeschoolers and others are doing their job.