Working for Freedom - Violence vs. Nonviolence

I've been thinking about Che Guevara (again) and how he chose to pick up the gun. I've been comparing him to people like Gandhi, Martin Luther King and Burma's Aung San San Kyi who have chosen nonviolence. I am not sure which is the more effective way. One wants to say that nonviolence is the way, but I wonder how many people have chosen this path and died and were never even heard of. I wonder if in some cases revolution is more effective in wresting freedom from the ones holding it.

I'm thinking about those empires in Egypt and in Turkey that swept in and replaced old empires; these did not happen peacefully. Alexander the Great, the Ottomans, and others had armies; they fought and conquered.

I agree that the more noble activity is to change the heart and mind, the actual chemistry of a human being - and this is what Gandhi, King, and Kyi have/are doing. But I think this works only with the help of the media.

When the media is repressed as in China and Burma, the world barely knows of the struggles for freedom within those countries. People die in those countries for their causes, and we don't even know of them.

Does change still happen even in these cases?

I'd read about how the anger of the oppressor is diminished when the oppressed does not fight back, but takes it. Theoretically, the oppressor runs out of anger.

Could this be true?