From the liner notes of a 1988 retrospective album by singer-songwriter Tom Paxton:

Jimmy Newman was written in the late 60's at the height of the build-up of violence in Vietnam. I think the Tet Offensive had come (and that we had "won") and we were all beginning to see that this thing would go on forever if the people didn't force it to stop.

On a more current note, Paxton posts some free music here. No matter what your politics, you may want to give a listen to "The Bravest."