Here’s a link to a video of Peter, Paul and Mary, singing Blowing In The Wind and Give Peace a Chance at a Washington Peace March in 1971:
Click here to watch the video.
Look for John Denver singing along on Give Peace A Chance. And the guy in the suit is Daniel Ellsberg, I believe.
Beautiful, and an amazing piece of history.
“For all the war dead.”
Metaphor 
Yup. Makes you wonder, doesn't it, whatever happened to all that energy, those benign, sweet feelings, that yearning for peace? I was a huge fan of PP&M, played their version of "If I Had a Hammer" every morning of my senior year, while I got dressed in my room in the frat house at Stanford. A powerful wake up song. Earlier, in the summer of 1961, when PP&M appeared in Honolulu, I scaled a chain link fence (tore the hell out of my Bermuda shorts) and broke into the concert, hid in some weeds at the top of the bowl and watched the first few tunes. A security guard then spotted me and — those were the days — smiled and flashed me a peace sign, ushered me to a vacant spot ten feet from the stage.Thanks, Kyle, for bringing it all back.