David Browne, Rolling Stone), opened the Woodstock festival in the summer of 1969. He wasn't meant to, but the band Sweetwater, scheduled to be the opening act, was stuck in traffic. He sang until he ran out of songs, but then began strumming his guitar vigorously and chanting "Freedom!" over and over, before segueing into the traditional spiritual "Sometimes I Feel Like a Motherless Child".
While I was at the Cosmic American Music Festival last September, I met (and heard some terrific music by) Walter Parks, who played lead guitar in Havens's group until the singer's death. Walter showed me a guitar, showing marks of hard use, that had belonged to Havens, and which he planned to take to the Brooklyn Lutherie for restoration. I wish I'd had the presence of mind to get a photo.
Photo: Wikimedia Commons (public domain).