"Say, Brother, Who Wrote This Melody?," by Robert W. Allen, has an interesting summary of the arguments concerning this tune which evolved into the "Battle Hymn of The Republic."
In brief, William Steffe (ca. 1830-1890) wrote the song and lyrics, under the title "Say, Bummers, Will You Meet Us," for the Good Will Engine Company of Philadelphia. Steffe, in an 1885 letter, said the words of the hymn, "Say, Brothers, Will You Meet Us" were composed by someone else, and that he couldn't remember the name.

The story is on this website: http://johnbrownsbody.net/SayBrother.htm
Say, Bummers
A rather ignoble beginning for "John Brown's Body" and "The Battle Hymn of the Republic."