Although he had many, this is probably Seeger's main signature song. A labor movement anthem-cum-all purpose activist hymn, he co-wrote it with Lee Hays, his partner in the Almanac Singers and the Weavers, in support of members of the United States Communist party who had recently been convicted under the 1940 Smith Act. The Weavers released it as a 78rpm single in 1950. Peter, Paul & Mary revived it and made it a top-10 hit in 1962, performing it at the 1963 March On Washington alongside Martin Luther King, Jr. (It was an even bigger hit for Trini Lopez that same year.) It would become a centerpiece of Seeger's solo sets, and a staple of musical protests – not to mention kindergarten sing-alongs – around the world.