Peaceful protest only works if politicians and financial elite has fear and/or respect towards the commond man/woman. Too much elitisms strips away the respect, too many years of peaceful protests takes away the fear. Sometimes ivory towers need to come down, but violence has a tendency to spread and spiral out of control. It's a balance trick.
Nelson Mandela was released on the terms that he would preach peaceful protest, as the movement he had formerly been leading was a serious threat to the South African Government.
Reverend Martin Luther King Jr was a proponent of peaceful protest, though it could be argued he was losing faith in it near the end when he was assassinated. right after his death, the Holy Week Uprisings occurred, which saw immediate action from the federal government to pass the Civil Rights Act.
At the same time, acts of violence lie on a spectrum, and I think there is a fair amount of conversation to be had about what degree of violence and what type of violence are most effective.
Martin Luther King Jr was able to succeed with his peaceful protests because the threat of Malcolm X was looming directly over his shoulder. One requires the other. Either of them alone would not have made nearly the progress they did.
I would say that both Malcolm X and MLK ultimately failed at their end goals, personally.
My bigger point was that the holy week uprising was able to progress things forward more in one week than either movement could do in the many years they were active. To be fair, I do not think the level of vigour and organization shown in the holy week uprising could have happened without the many liberation groups' prior work.
Ultimately, the use of violence is complex and how to effectively use it is just as complex. We should be discussing how to use all tactics and methods available, and not view violence as the only important component.
Yea only under the threat of violence has power ever changed hands. You need both peaceful and violent components to any movement to make any change last though.
Also: we've got where we are under threat of violence. Charlottesville and Jan 6 in the USA, the recent gammon riots in the UK, everything Putin does, etc, etc. The Authoritarians have weaponised both peace and violence against us.