Collectons of this song are from all over the American states and Canada.
Most collectors say it came out of the American Civil War. American Memory has a version from Cowell; they attribute the song to the Civil War. Peacock (Songs of the Newfoundland Outports) has it as "The Last Great Charge," and also assigns it to the American Civil War.
The Traditional Ballads Index has a list of versions and more examples have been found since then.

Such widespread songs usually started with a song sheet, or sheet music, thus an origin should be found; so far none has surfaced for this poem.
The Damon-Pythias type story is popular, and it is not surprising that the song spread.
No 19th century precursor has been found; although seemingly based on the Civil War. Perhaps a newspaper was the source, but a 1912 printing in the Boston Globe is the earliest so far. Belden found it in Missouri in 1903, the earliest so far.


Its use for incidents in the Napoleonic Wars, the Crimeam War, and the Indian Wars all seem to be late variants.