Maybe not exactly what you’re looking for, since it’s usually music written in the style of a march, but not actually for a military purpose, but have you thought of checking out some twentieth-century classical composers?
The first thing that popped into my head was the march from Hindemith’s Symphonic Metamorphosis (the march begins at about 4:06).
Then of course you’ve got Charles Ives, who took traditional American marches and contorted them every way he could imagine. Often he aimed to intentionally recreate effects in his compositions that he would hear as accidental results of the circumstances of real performances, such as two marching bands playing different things as they pass by each other, or firemen banging a gong out of time with the music. Check out They Are There (on this recording the composer sings and plays piano, adding a slightly more twisted element than the more usual arrangement for orchestra and chorus possesses), Gong on the Hook and Ladder, and The Circus Band.