As far as I am concerned, I don't think that violence is necessary to male things change. On the contrary when violence is used , the situation gets worse. .

Take many examples of non violent actions, Marthin Luther King's demonstrations and sitins and boycottings.All these events were led in a very pacific way.They led to The Civil Rights movement. An other exemple is in India , the action led by Gandhi in India.
His non violent action was beautifuly led against the British government and thanks to Ghandi India became independant. We musn't forget the very famous leader Mandelawho became South African president and  thanks to him, apartheid was abolished in that country. Tu pourras continuer...?