People like to give examples such as the civil rights' movement as the effectiveness of pacific demonstration, but that was just a good tactical decision made by Dr. King and other organizers, since they knew that police was ready to kill them at any excuse. In the case of black leaders of the time, any demonstration, even a pacific one, was able to make them subversive to the system.
https://kinginstitute.stanford.edu/king-papers/documents/ive... ... the American Negro collectively is richer than most nations of the world. We have an annual income of more than thirty billion dollars a year, which is more than all of the exports of the United States and more than the national budget of Canada. Did you know that? That's power right there, if we know how to pool it. (Yeah) [Applause] We don't have to argue with anybody. We don't have to curse and go around acting bad with our words. We don't need any bricks and bottles; we don't need any Molotov cocktails. (Yes) We just need to go around to these stores (Yes sir), and to these massive industries in our country (Amen), and say, "God sent us by here (All right) to say to you that you're not treating His children right. (That's right) And we've come by here to ask you to make the first item on your agenda fair treatment where God's children are concerned. Now if you are not prepared to do that, we do have an agenda that we must follow. And our agenda calls for withdrawing economic support from you."
Obviously Dr. King didn't realise that economic sanctions are a form of violence monopolised by state level actors?