“Most groups feel they are justified in their actions of using force, and are "responding".”

Ever heard the phrase “he cries out as he strikes at you”? What people claim or even feel doesn’t make their claim true. And even if people are truly retaliating against someone else’s initial aggression, it doesn’t mean the retaliators are necessarily right wing or any other political bent. You’ve provided an example of the rhetorical fallacy known as:

Composition: Assuming that characteristics or beliefs of some of a group applies to the entire group. “Recent terrorist attacks have been carried out by radical Islamic groups. Therefore all terrorists are muslims.””

In your case, it’s ‘some retaliations have been carried out by right wingers, therefore all retaliators are right wingers’

WWII is complicated and its causes go back to before WWI, so I’m not getting into it. The point is that just because some German socialists were traditionally religious, it didn’t make them rightwing. Some American churches are swamped with leftists who advocate for the bureaucratic extortion of their own countrymen.