Here's a protest primer:

"1913 Massacre," Woody Guthrie

"A Change Is Gonna Come," Sam Cooke

"Masters of War," Bob Dylan

"Ringing of Revolution," Phil Ochs

"Mississippi Goddam," Nina Simone

"Ballad of Sacco & Vanzetti," Joan Baez

"Man in Black," Johnny Cash

"The Revolution Will Not Be Televised," Gil Scott-Heron

"What's Going On?" Marvin Gaye

"Sunday Bloody Sunday," U2

"Washington Bullets," The Clash

"Little Man with a Gun in his Hand," Minutemen

"Flowers of Guatemala," R.E.M.

"Black Steel in the Hour of Chaos," Public Enemy

"Talkin' 'bout a Revolution," Tracy Chapman

"Lost Woman Song," Ani DiFranco

"Killing in the Name," Rage Against the Machine

"Fijate Bien," Juanes

"What the Po-Pos Hate," The Coup

"The Revolution Starts. . . Now," Steve Earle