They help attempt to repel black death, 1349. they were religious zealots of the middle ages in Europe who demonstrated their religious fervor and sought atonement for their sins by vigorously whipping themselves in public displays of penance.
If you mean WW2, its because America wanted isolationism and didn't want to fight in the war. They were able to stay out of it for as long as they did because they didn't take sides.
