Sham battle at the Pan-American Exposition, 1901
The link from the Library of Congress is here: Sham battle at the Pan-American Exposition. (A Thomas A. Edison, Inc. film from 1901.) From the summary: "Large arches and columns are seen surrounding a flat field. In the foreground of the field, some American Indians on horseback ride toward the camera. The Indians are wearing feathers, war paint, and are carrying frontier rifles across the bare backs of their horses. In the middle of this flat area, men dressed as U.S. Army troops in battle regalia are lined up in the position of skirmishers. They fire at the Indians, who gallop by. The troops move over this flat area while the Indians on horseback circle them."
What's especially interesting is that back in 1901 a couple of the very same modern reenactment "things" are apparent in this film, namely, a lack of hits being taken and elevated muskets (rifles) as the opponents come to close to one another, etc.
This was filmed in Buffalo, New York, and is probably the very first movie footage of a reenacted or sham battle ever taken.