Exciting historical times offer up cultural artifacts that reflect on those times. I remember well reading the Rolling Stone "official" history of rock and roll (pretty standard fluff, but full of good stuff in the early chapters on American folk musics), for example, that the Second World War offered, among many other things such as death and destruction, a whole host of songs, popular and folk, on the event; the Korean War, on the other hand, only one B.B. King song, "Korea Blues".
The Civil Rights movement also had its poets laureate and songsters. While I wouldn't necessarily include Bob Dylan as an official "chronicler", he participated and supported the movement in his own way (including sitting around and holding hands, singing "Kum Ba Yah"). Yet, as he reflected more deeply, "The Times They Are A-Changing" came out, a far more reflective and threatening musical manifesto.
Sam Cooke's most powerful song, "A Change Is Gonna Come", was his offering to the world, stripped either of a desire to please the Lord or seek the gains of filthy lucre. As such, it managed to do both. My own sense is, had he lived, his voice would have rung out for many years to come.
It predates the Civil Rights movement; it was really part of the leftist, socialist/communist infiltrated, yet nonetheless necessary anti-lynching movement of the 1920's and 1930's (one of FDR's more cowardly moments; he knew a federal anti-lynching statute was necessary; he supported the idea; he also knew the resistance of southern Senators, especially if it passed, would doom the New Deal legislation he saw as far more important). This song was written for Billie Holiday, and she was afraid of it - its bleakness, its baldness, and the threat it seemed to pose. Yet, along with "God Bless The Child" and "Autumn in New York", it is my favorite musical performance of hers because she made it her own. For all the ravages his life of dissipation left on her face and body, it really didn't touch her voice, especially as she sings this song.