TIL that the Battle Hymn of the Republic was an abolitionist song and based on another abolitionist song:

The "Battle Hymn of the Republic" is an American patriotic song written by the abolitionist writer Julia Ward Howe during the American Civil War.

Howe adapted her song from the soldiers' song "John Brown's Body" in November 1861, and sold it for $4 to The Atlantic Monthly[1] in February 1862. In contrast to the lyrics of the soldiers' song, her version links the Union cause with God's vengeance at the Day of Judgment (through allusions to biblical passages such as Isaiah 63:1–6, Revelation 19 and Revelation 14:14–19).

Julia Ward Howe was married to Samuel Gridley Howe, a scholar in education of the blind. Both Samuel and Julia were also active leaders in anti-slavery politics and strong supporters of the Union. Samuel was a member of the Secret Six, the group who funded John Brown's work.

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