Bob Dylan's "Masters of War" is probably the ultimate protest song, with its in your face attitude and angry tone. While I have sometimes wondered whether the anger is counter-productive or not, I found that I had a lot of passion in my delivery. Have a look, and decide for yourself.
Eric Bogle is a songer/songwriter from Australia, best known for the song "And the Band Played Waltizing Matilda." "My Youngest Son Came Home Today" is another of his classics, and although he is singing about Ireland, the sentiment behind it can be applied to any situation where a parent loses a child who is a soldier. Here it is.