We shall overcome, hey? Interesting history to that song. It came out of the Highlander Folk School, a leftist organization very active in "social justice", labor unionization in the south, but most famously for involvement in the Civil Rights movement.

"Highlander has provided training and education for the labor movement in Appalachia and throughout the Southern United States. During the 1950s, it played a critical role in the American Civil Rights Movement. It trained civil rights leader Rosa Parks prior to her historic role in the Montgomery Bus Boycott, as well as providing training for many other movement activists including the members of the Student Nonviolent Coordinating Committee (SNCC), Septima Clark, Anne Braden, Martin Luther King, Jr., James Bevel, Hollis Watkins, Bernard Lafayette, Ralph Abernathy and John Lewis in the mid- and-late 1950s."

It was at Highlander the famous picture of MLK with the Communist Party organizer Donald Lee West, one of the founders of Highlander, was taken.

The song itself was originated with a group run by far Leftist Pete Singer and it's no coincidence that Castro's revolutionary cabal was called the Venceremos (We shall conguer or we shall overcome) Brigade and was also the name chosen by elements of the SDS to show solidarity with the Castro regime.

http://en.wikipedia.org/wiki/We_Shall_Overcome
http://en.wikipedia.org/wiki/Highlander_Folk_School