A few years ago I made for my personal use a CD mix I called Peace Songs, songs for the promotion of peace but including some detailing the adverse effects of war, among these were:
Where Have All the Flowers Gone? - Pete Seeger, Joe Hickerson and the German version Sag mir wo die Blumen sind, sung in Israel by Marlene Dietrich
Mothers, Daughters, Wives - Judy Small
Flowers of the Forest - traditional Scots
Killiecrankie - Robert Burns
The First Battalion's Home, Yes I See, Two Brothers - American Civil War Trilogy- Bob Camp, Bob Gibson
No Man's Land - Eric Bogle
The Band Played Waltzing Matilda - Eric Bogle
Dancing at Whitsun - Austin John Marshall
Ballad of the Soldier's Wife - Berthold Brecht/Kurt Weill
Rosemary's Sister - Huw and Tony Williams
I Come and Stand at Every Door (Dead Girl of Hiroshima)- Nazim Hikmet
Come Seamus and Ivy - Northern Ireland, can't find author, sung by Meg Davis
Come Away Melinda - Fred Hellerman, Fran Minkoff