When I'm Gone by Phil Ochs is, arguably, not primarily a protest song but I'm bagging it for this thread anyway. It's lovely poetry, and this verse is sublime for me:

Won't see the golden of the sun when I'm gone
And the evenings and the mornings will be one when I'm gone
Can't be singing louder than the guns when I'm gone
So I guess I'll have to do it while I'm here