Who was he? Besides being a singer, he was an activist for peace and sustainability, at times challenging the "establishment" which would have clamored for war and curtailed freedoms of ordinary citizens. Quoting from the annotations to the video below:
"On July 26, 1956, the House of Representatives voted 373 to 9 to cite Pete Seeger and seven others (including playwright Arthur Miller) for contempt, as they failed to cooperate with House Un-American Activities Committee (HUAC) in their attempts to investigate alleged subversives and communists. Pete Seeger testified before the HUAC in 1955.
In one of Pete's darkest moments, when his personal freedom, his career, and his safety were in jeopardy, a flash of inspiration ignited this song. The song was stirred by a passage from Mikhail Sholokhov's novel "And Quie Flows the Don". Around the world the song traveled and in 1962 at a UNICEF concert in Germany, Marlene Dietrich, Academy Award-nominated German-born American actress, first performed the song in French, as "Qui peut dire ou vont les fleurs?" Shortly after she sang it in German. The song's impact in Germany just after WWII was shattering. It's universal message, "let there be peace in the world" did not get lost in its translation. To the contrary, the combination of the language, the setting, and the great lyrics has had a profound effect on people all around the world. May it have the same effect today and bring renewed awareness to all that hear it."