Gandhi's nonviolent stance was one of the forces behind Martin Luther Kings, Jr.'s nonviolent protests during the Civil Rights Movement. It has great merit, indeed.
There were also other forces at play during that time.
"Laws serve to deter crime and protect the weak from the strong in civilized society. Where there is a breakdown of law, where is the force of deterrent? Only highly civilized and moral individuals respect the rights of others. The southern brute respects only force. Nonviolence is a very potent weapon when the opponent is civilized, but nonviolence is no repellent for a sadist.
I have great respect for the pacifist, that is for the pure pacifist. I am not a pacifist and I am sure I may safely say most of my people are not. Passive resistance is a powerful weapon in gaining concessions from oppressors, but I venture to say that if Mack Parker (a black man lynched in 1959) had had an automatic shotgun at his disposal, he could have served as a great deterrent against lynching." - Robert F. Williams,
Liberation Magazine (September 1959)
Robert F. Williams was a very influential black activist during the time of the Dr. Martin Luther King Jr. nonviolent protests as well as a NAACP leader. However, Robert Williams made use of of machine guns and explosives to defend his rights. He eventually ended up fleeing to Cuba. I believe that he died of natural causes a few years ago.