Olivier Messiaen, Quatuor pour la fin du Temps (quartet for the end of time) was the first one I thought of. It was written in 1941 while the composer was interned in the German Stalag VIII-A POW camp. I'm fairly sure I've listened to it but I don't remember anything about what it was like. Its fame is partly from the circumstances of its composition and premiere.

https://en.wikipedia.org/wiki/Quatuor_pour_la_fin_du_temps

And on a lighter(?) note, Tom Lehrer, So Long Mom.