Fuld (The Book of World-Famous Music, pp. 657-658) wrote, "...a generally similar melody in the major, without words, appears under the title "Rogues' March" in E. A. Dolph, "Sound Off" ... 1929, p. 72. While no earlier printing of the Rogues' March has been found, the tune appears under this title in several early undated American musical manuscript books, e. g., "Enoch Peirce's Book, Newburyport," circa 1800, at page 113; Irving Lowens, Baltimore."
   "A somewhat closer approximation to the above-quoted melody, but in the major and without words, was under the title "Army Duff" in "A Musical Switch," Humoresque, adapted and arranged by Kenneth J. Alford for military band parts, a set of which was deposited at BM [British Museum] on April 20, 1921,.... "A Musical Switch" is a medley of 44 familiar tunes, "Army Duff" appearing on p. 6.... of the score.
'Duff' is the pudding, and is applied to a slow, heavy tune, according to an ex-British Army musician, W. D. Trigg.

"Almost the same melody, also in the major and without words, appears as "The Elephant Walk," arranged for children and published in 1948 by J. J. Robbins & Sons, Inc., New York..."
...
   "As "The Worms Crawl In," the song seems to have become popular during World War 1- as the hearse rolled by on the battlefield, one soldier told another...; in the third stanza or so, the worms crawl in, the worms crawl out..." "Its first known printing in this form, and in the minor and with words, was Annetta Eldridge and Ruth E. Richardson, "Stunt Songs for Social Sings" (Denver, CO. and Franklin, OH), p. 25, under the title "Hearse Song;" this booklet was first published Nov. 14, 1923..." [Later appeared in Sandburg, 1927, p. 444].

Thus, possibly a military drum or marching tune which acquired words.
I have not found any information that adds anything significantly to Fuld's exposition.