Another couple of suggestions...

"McCafferty" ("McCaffery" in some versions), a song about injustice between the ranks in the British army and the terrible consequences it brings to the individuals involved.

Maybe also "Moreton Bay" (I have at least two versions of this) about the terrible punishments meted out to convicts round about the 1820s in a penal colony in Australia by the infamous and cruel army officer in charge (in the song he gets his fully deserved come-uppance in the end).

Best of luck with the project Beth!

Cheers

mooman