Socially-engaged major Progressive Rock

I've been thinking that it could be interesting to have a thread about the socially-engaged "songs" included in the poll series "Thinking politically / socially-engaged songs", and I can tell now that my selections have mainly focused on major Prog. Also in this new thread, you can post some more of the same kind.

Anyway, here're most of the "songs" from the poll series (Edit: plus some of those posted in this thread):

Ange - "Les Longues Nuits D'Isaac" (1974)

Area - "Gioia e Rivoluzione" (1975)

Curved Air - "Marie Antoinette"  (1972)

Eloy - "The Light from Deep Darkness" (1974)

Genesis - "The Knife" (1970)

Jethro Tull - "Wind-Up" (1971)

King Crimson - "21st Century Schizoid Man" (1969)