The "antiwar song" as a recognizable category didn't appear in the U.S till the 1950s or '60s. It was barely noticeable before 1965 and the Vietnam War.

BTW, principal credit for "I Didn't Raise my Boy to be a Soldier" goes to Alfred Bryan, the lyricist, and Al Piantadosi, the composer.

It was revived by American isolationists and others in 1939-1941.