"Feel like I'm fixin' to die rag" --- mm, maybe not.

"Strangest Dream" is a good suggestion, and easy to sing.

Or the round "Dona Nobis Pacem" (Tr. = Give us peace)

Or perhaps "Buttermilk Hill"...war from a woman's point of view

Or perhaps a discussion of the two views of war in two songs with the same tune: "Johnny I hardly knew ye" and "When Johnny comes marching home again." Discussing them in the context of the American Civil War might help the kids deal with the bleaker side of war by distancing it a bit. Or else use them as a jumping off point to discuss the media presentations of the war in Iraq before and after it started. Gung ho before we went in, but dwelling out all the alleged incompetancies and casualties now that the fighting is underway (like they expected it to be bloodless and 100% free of civilian casualties, let alone accidents and friendly fire).

That's my $0.02 worth, I'm sure other 'Catters will have more and better ideas!