I listened to many versions before singing it at the Mudcat singaround earlier today. The "soldiers die and empires fall" line might have come from Jomi Mitchell. So far as I know, she never recorded the song, but she did sing it in her concerts back in the day, and there's a Youtube recording of her singing it at an outdoor concert, maybe at a music festival, with Crosby Stills and Nash, and John Sebastian on stage with her.

My guess: Valenti never settled on one consistent set of lyrics, and what other artists recorded depended on what version Valenti sang when they got it from him.

I heard the Mitchell Trio recording (with John Denver) before the Youngbloods released theirs.