Hollis Watkins sings in memory of Medgar Evers during a wreath-laying ceremony Thursday, May 16, 2013, at the Jackson, Miss., home of Evers, the Mississippi NAACP leader who was assassinated in 1963.

Hollis Watkins, who started challenging segregation and racial oppression in his native Mississippi when he was a teenager and toiled alongside civil rights icons including Medgar Evers and Bob ...