The main tune is widely recognised as "Battle Hymn of the Republic" with the lyrics of Julia Ward Howe. It is traditionally played at an allegretto in a flat key. The theme isn't stated in this traditional fashion until the very end. I tried to make this piece sound as little like a theme and set of variations as possible, and that can be seen by observing the vast amounts of original material I've thrown in to complement and transition between 'variations'.
Just to clear this up, I can personally play the entire horn part quite decently, and I am only an amateur. The part is not meant to be easy. Also, although it may say "Solo" in the horn part, this is not a horn concerto. I treat the horn as part of the ensemble and give the strings much of the important material as well.
A brief synopsis...
• Intro and first variation: Theme put in minor, very grave. Theme starts in the horn.
• Second variation (at
B): Theme still in minor, only much more agitated, with an attitude.
• Third variation (at
C): Waltz time, theme in major, put in basses, and then horn.
o From letter
E to letter
F is a transition comprised of original material, and bits of the theme.
• Fourth variation (at
F): Opens with a mysterious 5/8 pattern. First thing in the violins is original material to help get the ear to tune into the odd meter. At measure 184, first violins have the theme in inversion, very obscure. Measure 213 is a reprise in a 4/4 march style with the theme in retrograde.
• Original theme and ending: (at
I) Traditional tempo, key, and voicing; no changes.
MIDI:
Variations-John-Browns-Body.mid
I would make an MP3, but the SoftSynth strings patches in Finale leave much to be desired, and they are all I have.
PDF:
Variations_John Brown's Body - eSnips, share anything
(thanks to Marius for producing my .pdf, as my two PDF creators have somehow broken, oddly enough. They just don't work anymore. I can also thank Marius for the occasional advice here and there (which goes along the lines of me asking him, "Is this okay? How do I indicate this? Is this too abrupt?" 
) )
I've become rather proud of this piece, but I know there are some flaws. If anybody has anything to point out, I will accept comments in all areas, including score layout.