The song "Volunteers" was co-written by Paul Kantner (guitar) and Marty Balin (vocals), the song is saying to take a stand against the US government and the war in Vietnam.
An interview from 1993 in the music magazine  Relix, Marty Balin stated "It became political but it didn't start out that way. I had woken up to the sound of garbage cans crashing outside the mansion and looked out, and there was this Volunteers of America truck, so I wrote that down and gave it to Paul and he wrote the song. Bang. People put all kinds of meaning into it."
The last album the band recorded was 'Volunteers' after which there were massive personnel changes which altered their original sound: Psychedelic Rock.