No matter which genre writes which anti-war song / antimilitarist / pacific songs impress you most.
"A Lifetime of War" by Sabaton I find quite well. Sabaton is a Swedish Heavy Metal band that sings about military historical topics.
Also "The Price Of A Mile "is good, there is just about the First World War and how much you have paid for little country you could say.
"Cliffs of Gallipoli" can also be seen as an anti war song, but it's more to conquer the futility of the campaign to Gallipoli.
Brothers in Arms. Diree Straits. Goose bumps. Last text line, Now The Sun Goes to Hell, The Moon Riding High, Let Me BitYou Farewell, Every Man Has To the, But Its Writting in The Star Light, In Every Line in Your Heart, We're Fools to Make was on our Brothers in Arms.
The Band Played Waltzing Mathilda
This is an Australian song about the battle of Gallipoli, in the 1st WK, the Allies (Entente) against the Ottoman Empire. One of the most senseless and bloodiest battles of the 1st World War, a battle, which was especially for Australia, and its army, traumatic.
The version of the pogues, with text.
"I did not know that there were things worse like death"
1916 of Motörhead
Green Fields of France of Dropkick Murphys
Avril Lavigne - We Are Warriors